draft-ietf-manet-dymo-22.txt   draft-ietf-manet-dymo-23.txt 
Mobile Ad hoc Networks Working Group C. Perkins Mobile Ad hoc Networks Working Group C. Perkins
Internet-Draft Internet-Draft Futurewei
Intended status: Standards Track I. Chakeres Intended status: Standards Track I. Chakeres
Expires: September 13, 2012 CenGen Expires: April 26, 2013 CenGen
March 12, 2012 October 23, 2012
Dynamic MANET On-demand (AODVv2) Routing Dynamic MANET On-demand (AODVv2) Routing
draft-ietf-manet-dymo-22 draft-ietf-manet-dymo-23
Abstract Abstract
The Dynamic MANET On-demand (AODVv2) routing protocol is intended for The Dynamic MANET On-demand (AODVv2) routing protocol is intended for
use by mobile routers in wireless, multihop networks. AODVv2 use by mobile routers in wireless, multihop networks. AODVv2
determines unicast routes among AODVv2 routers within the network in determines unicast routes among AODVv2 routers within the network in
an on-demand fashion, offering on-demand convergence in dynamic an on-demand fashion, offering on-demand convergence in dynamic
topologies. topologies.
Status of this Memo Status of this Memo
skipping to change at page 1, line 35 skipping to change at page 1, line 35
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This Internet-Draft will expire on September 13, 2012. This Internet-Draft will expire on April 26, 2013.
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Table of Contents Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Applicability Statement . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Applicability Statement . . . . . . . . . . . . . . . . . . . 7
4. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 7 4. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Route Table Entry . . . . . . . . . . . . . . . . . . . . 7 4.1. Route Table Entry . . . . . . . . . . . . . . . . . . . . 8
4.2. AODVv2 Messages . . . . . . . . . . . . . . . . . . . . . 8 4.2. AODVv2 Message Structure and Information Elements . . . . 9
4.2.1. Generalized Packet and Message Structure . . . . . . . 9 4.3. RteMsg-specific Protocol Elements . . . . . . . . . . . . 11
4.2.2. Routing Message (RteMsg) - RREQ and RREP . . . . . . . 10 4.4. Route Error (RERR)-specific Protocol Elements . . . . . . 12
4.2.3. Route Error (RERR) . . . . . . . . . . . . . . . . . . 11 5. Detailed Operation for the Base Protocol . . . . . . . . . . . 13
5. Detailed Operation . . . . . . . . . . . . . . . . . . . . . . 12 5.1. AODVv2 Sequence Numbers . . . . . . . . . . . . . . . . . 13
5.1. AODVv2 Sequence Numbers . . . . . . . . . . . . . . . . . 12 5.1.1. Maintaining A Node's Own Sequence Number . . . . . . . 13
5.1.1. Maintaining A Node's Own Sequence Number . . . . . . . 12 5.1.2. Actions After OwnSeqNum Loss . . . . . . . . . . . . . 13
5.1.2. Numerical Operations on OwnSeqNum . . . . . . . . . . 13
5.1.3. OwnSeqNum Rollover . . . . . . . . . . . . . . . . . . 13
5.1.4. Actions After OwnSeqNum Loss . . . . . . . . . . . . . 13
5.2. AODVv2 Routing Table Operations . . . . . . . . . . . . . 13 5.2. AODVv2 Routing Table Operations . . . . . . . . . . . . . 13
5.2.1. Judging Routing Information's Usefulness . . . . . . . 13 5.2.1. Judging Routing Information's Usefulness . . . . . . . 13
5.2.2. Creating or Updating a Route Table Entry with 5.2.2. Creating or Updating Route Table Entries . . . . . . . 15
Received Preferable Routing Information . . . . . . . 15 5.2.3. Route Table Entry Timeouts . . . . . . . . . . . . . . 15
5.2.3. Route Table Entry Timeouts . . . . . . . . . . . . . . 16
5.3. Routing Messages . . . . . . . . . . . . . . . . . . . . . 16 5.3. Routing Messages . . . . . . . . . . . . . . . . . . . . . 16
5.3.1. RREQ Creation . . . . . . . . . . . . . . . . . . . . 16 5.3.1. RREQ Creation . . . . . . . . . . . . . . . . . . . . 16
5.3.2. RREP Creation . . . . . . . . . . . . . . . . . . . . 17 5.3.2. RREP Creation . . . . . . . . . . . . . . . . . . . . 17
5.3.3. RteMsg Handling . . . . . . . . . . . . . . . . . . . 18 5.3.3. RteMsg Handling . . . . . . . . . . . . . . . . . . . 18
5.4. Route Discovery . . . . . . . . . . . . . . . . . . . . . 21 5.4. Route Discovery . . . . . . . . . . . . . . . . . . . . . 20
5.5. Route Maintenance . . . . . . . . . . . . . . . . . . . . 22 5.5. Route Maintenance . . . . . . . . . . . . . . . . . . . . 21
5.5.1. Active Next-hop Router Adjacency Monitoring . . . . . 22 5.5.1. Active Next-hop Router Adjacency Monitoring . . . . . 21
5.5.2. Updating Route Lifetimes During Packet Forwarding . . 23 5.5.2. Updating Route Lifetimes During Packet Forwarding . . 22
5.5.3. RERR Generation . . . . . . . . . . . . . . . . . . . 23 5.5.3. RERR Generation . . . . . . . . . . . . . . . . . . . 22
5.5.4. RERR Handling . . . . . . . . . . . . . . . . . . . . 24 5.5.4. RERR Handling . . . . . . . . . . . . . . . . . . . . 23
5.6. Unknown Message and TLV Types . . . . . . . . . . . . . . 25 5.6. Unknown Message and TLV Types . . . . . . . . . . . . . . 24
5.7. Advertising Network Addresses . . . . . . . . . . . . . . 25 5.7. Advertising Network Addresses . . . . . . . . . . . . . . 24
5.8. Simple Internet Attachment . . . . . . . . . . . . . . . . 25 5.8. Simple Internet Attachment . . . . . . . . . . . . . . . . 24
5.9. Multiple Interfaces . . . . . . . . . . . . . . . . . . . 27 5.9. Multiple Interfaces . . . . . . . . . . . . . . . . . . . 25
5.10. AODVv2 Control Packet/Message Generation Limits . . . . . 27 5.10. AODVv2 Control Packet/Message Generation Limits . . . . . 26
6. Administratively Configured Parameters and Timer Values . . . 27 5.11. Optional Features . . . . . . . . . . . . . . . . . . . . 26
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 5.11.1. Expanding Rings Multicast . . . . . . . . . . . . . . 26
7.1. AODVv2 Message Types Specification . . . . . . . . . . . . 30 5.11.2. Intermediate RREP . . . . . . . . . . . . . . . . . . 27
7.2. Message and Address Block TLV Type Specification . . . . . 30 5.11.3. Precursor Notification . . . . . . . . . . . . . . . . 27
7.3. Address Block TLV Specification . . . . . . . . . . . . . 31 5.11.4. Reporting Multiple Unreachable Nodes . . . . . . . . . 28
8. Security Considerations . . . . . . . . . . . . . . . . . . . 31 5.11.5. Message Aggregation . . . . . . . . . . . . . . . . . 28
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 32 5.11.6. Adding Additional Routing Information to a RteMsg . . 29
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 33 5.12. Administratively Configured Parameters and Timer Values . 30
10.1. Normative References . . . . . . . . . . . . . . . . . . . 33 5.13. IANA Considerations . . . . . . . . . . . . . . . . . . . 33
10.2. Informative References . . . . . . . . . . . . . . . . . . 33 5.13.1. AODVv2 Message Types Specification . . . . . . . . . . 33
Appendix A. Changes since the Previous Version . . . . . . . . . 34 5.13.2. Message and Address Block TLV Type Specification . . . 33
Appendix B. Proposed additional changes for LOADng conformance . 34 5.13.3. Address Block TLV Specification . . . . . . . . . . . 34
Appendix C. Shifting Responsibility for an Address Between
AODVv2 Routers . . . . . . . . . . . . . . . . . . . 35 5.14. Security Considerations . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 35 5.15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 36
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36
6.1. Normative References . . . . . . . . . . . . . . . . . . . 36
6.2. Informative References . . . . . . . . . . . . . . . . . . 37
Appendix A. Changes since the Previous Version . . . . . . . . . 38
Appendix B. Shifting Network Prefix Advertisement Between
AODVv2 Routers . . . . . . . . . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39
1. Overview 1. Overview
The Dynamic MANET On-demand (AODVv2) routing protocol enables on- The Dynamic MANET On-demand (AODVv2) routing protocol [formerly named
demand, multihop unicast routing among participating AODVv2 routers. DYMO] enables on-demand, multihop unicast routing among AODVv2
The basic operations of the AODVv2 protocol are route discovery and routers in mobile ad hod networks [MANETs][RFC2119]. The basic
route maintenance. Route discovery is performed when an AODVv2 operations of the AODVv2 protocol are route discovery and route
router receives a packet from a node under its responsibility to a maintenance. Route discovery is performed when an AODVv2 router must
destination for which it does not have a route. Route maintenance is transmit a packet towards a destination for which it does not have a
performed to help ensure that the route being used to forward packets route. Route maintenance is performed to avoid dropping packets,
from the source to the destination remains operational. when a route being used to forward packets from the source to a
destination breaks, and to avoid prematurely expunging routes from
the route table.
During route discovery, the originator's AODVv2 router initiates During route discovery, an AODVv2 router initiates flooding of a
dissemination of a Route Request (RREQ) throughout the network to Route Request message (RREQ) throughout the network to find a route
find a route to a particular destination, via the AODVv2 router to a particular destination, via the AODVv2 router responsible for
responsible for this destination. During this hop-by-hop this destination. During this hop-by-hop flooding process, each
dissemination process, each intermediate AODVv2 router records a intermediate AODVv2 router receiving the RREQ message records a route
route to the originator. When the target's AODVv2 router receives to the originator. When the target's AODVv2 router receives the
the RREQ, it responds with a Route Reply (RREP) sent hop-by-hop RREQ, it records a route to the originator and responds with a Route
toward the originating AODVv2 router. Each intermediate AODVv2 Reply (RREP) unicast hop-by-hop toward the originating AODVv2 router.
router that receives the RREP creates a route to the target, and then Each intermediate AODVv2 router that receives the RREP creates a
the RREP is unicast hop-by-hop toward the originator. When the route to the target, and then the RREP is unicast hop-by-hop toward
originator's AODVv2 router receives the RREP, routes have then been the originator. When the originator's AODVv2 router receives the
established between the originating AODVv2 router and the target RREP, routes have then been established between the originating
AODVv2 router in both directions. AODVv2 router and the target AODVv2 router in both directions.
Route maintenance consists of two operations. In order to preserve Route maintenance consists of two operations. In order to preserve
routes in use, AODVv2 routers extend route lifetimes upon routes in use, AODVv2 routers extend route lifetimes upon
successfully forwarding a packet. In order to react to changes in successfully forwarding a packet. In order to react to changes in
the network topology, AODVv2 routers monitor traffic being forwarded. the network topology, AODVv2 routers monitor traffic being forwarded.
When a data packet is received for forwarding and a route for the When a data packet is received for forwarding and a route for the
destination is not known or the route is broken, then the AODVv2 destination is not known or the route is broken, then the AODVv2
router of the source of the packet is notified. A Route Error (RERR) router of the source of the packet is notified. A Route Error (RERR)
is sent toward the packet source to indicate the route to particular is transmitted to indicate the route to one or more affected
destination addresses is invalid or missing. When the source's destination addresses is Broken or missing. When the source's AODVv2
AODVv2 router receives the RERR, it deletes the route. If this router receives the RERR, it marks the route as broken. Before the
source's AODVv2 router later receives a packet for forwarding to the AODVv2 router can forward a packet to the same destination, it has to
same destination, it will need to perform route discovery again for perform route discovery again for that destination.
that destination.
AODVv2 uses sequence numbers to ensure loop freedom [Perkins99].
Sequence numbers enable AODVv2 routers to determine the temporal
order of AODVv2 route discovery messages, thereby avoiding use of
stale routing information.
2. Applicability Statement
The AODVv2 routing protocol is designed for stub or disconnected
mobile ad hoc networks (MANETs). AODVv2 handles a wide variety of
mobility patterns by dynamically determining routes on-demand.
AODVv2 also handles a wide variety of traffic patterns. In networks
with a large number of routers, AODVv2 is best suited for sparse
traffic scenarios where routers forward packets to only a small
portion of the other AODVv2 routers, due to the on-demand nature of
route discovery and route maintenance.
AODVv2 is applicable to memory constrained devices, since little
routing state is maintained in each AODVv2 router. Only routing
information related to active sources and destinations is maintained,
in contrast to most proactive routing protocols that require routing
information to all routers within the routing region be maintained.
AODVv2 supports routers with multiple interfaces participating in the
MANET. AODVv2 routers can also perform routing on behalf of other
nodes, attached via participating or non-participating interfaces.
AODVv2 routers perform route discovery to find a route to a
particular destination. Therefore, AODVv2 routers MUST be configured
to initiate and respond to route discovery on behalf of certain
nodes, identified by address. When AODVv2 is the only protocol
interacting with the forwarding table, AODVv2 MAY be configured to
perform route discovery for all unknown unicast destinations.
At any time within an AODVv2 routing region, only one AODVv2 router
SHOULD be responsible for, i.e. "own", any particular address.
Coordination among multiple AODVv2 routers to distribute routing
information correctly for a shared address (i.e. an address that is
advertised and can be reached via multiple AODVv2 routers) is not
described in this document. The router behavior for shifting
responsibility for an address from one AODVv2 router to another is
mentioned in Appendix C.
AODVv2 only utilizes bidirectional links. In the case of possible
unidirectional links, either blacklists (see Section 7.2) or other
means (e.g. adjacency establishment with only neighboring routers
that have bidirectional communication as indicated by NHDP
[I-D.ietf-manet-nhdp]) of ensuring and monitoring bi-directionality
is recommended. Otherwise, persistent packet loss may occur.
The routing algorithm in AODVv2 may be operated at layers other than Similarly to AODV, AODVv2 uses sequence numbers to ensure loop
the network layer, using layer-appropriate addresses. freedom [Perkins99]. Sequence numbers enable AODVv2 routers to
determine the temporal order of AODVv2 route discovery messages,
thereby avoiding use of stale routing information. Also, AODVv2 uses
RFC 5444 message and TLV formats.
3. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
Additionally, this document uses some terminology from [RFC5444]. Additionally, this document uses some terminology from [RFC5444].
This document defines the following terminology: This document defines the following terminology:
Adjacency Adjacency
A relationship between selected bi-directional neighboring routers A relationship between selected bi-directional neighboring routers
for the purpose of exchanging routing information. Not every pair for the purpose of exchanging routing information. Not every pair
of neighboring routers will necessarily form an adjacency. of neighboring routers will necessarily form an adjacency.
Neighboring routers may form an adjacency based several different Neighboring routers may form an adjacency based on various
pieces of information or protocols; for example, exchange of information or other protocols; for example, exchange of AODVv2
AODVv2 routing messages, other protocols (e.g. NDP [RFC4861] or routing messages, other protocols (e.g. NDP [RFC4861] or NHDP
NHDP [I-D.ietf-manet-nhdp]), or manual configuration. Similarly, [RFC6130]), or manual configuration. Loss of a routing adjacency
loss of a routing adjacency may also be based upon several pieces may also be based upon similar information; monitoring of
of information, and monitoring of adjacencies where packets are adjacencies where packets are being forwarded is required (see
being forwarded is required (see Section 5.5.1). Section 5.5.1).
Distance (Dist) Distance (Dist)
A metric of the distance a message or piece of information has An unsigned integer which measures the distance a message or
traversed. The minimum value of distance is the number of IP hops information element has traversed. The minimum value of distance
traversed. The maximum value is 65,535. is the number of IP hops traversed, 0 for local information. The
maximum value is 254. The value 255 is reserved to indicate that
the distance is unknown.
AODVv2 Sequence Number (SeqNum) AODVv2 Sequence Number (SeqNum)
An AODVv2 Sequence Number is maintained by each AODVv2 router An AODVv2 Sequence Number is an unsigned integer maintained by
process. This sequence number is used by other AODVv2 routers to each AODVv2 router. This sequence number guarantees the temporal
identify the temporal order of routing information generated and order of routing information to maintain loop-free routes. The
ensure loop-free routes. value zero (0) is reserved to indicate that the SeqNum for a
destination address is unknown.
Multihop-capable Unicast IP Address reactive
A multihop-capable unicast IP address is a unicast IP address that A protocol operation is said to be "reactive" if it is performed
when put into the IP.SourceAddress or IP.DestinationAddress field only in reaction to specific events. As used in this document,
is scoped sufficiently to be forwarded by a router. Globally- "reactive" is essentially synonymous with "on-demand".
scoped unicast IP addresses and Unique Local Addresses (ULAs) are
examples of multihop-capable unicast IP addresses. Router Client
An AODVv2 router may be configured with a list of other IP
addresses and networks which correspond to other non-router nodes
which require the services of the AODVv2 router for route
discovery and maintenance. An AODVv2 is always its own client, so
that the list of client IP addresses is never empty. corresponds
to the AODVv2 router process currently performing a calculation or
processing a message.
Flooding
In this document, flooding a message refers to the process of
delivering the message to every AODVv2 router in the network.
This may be done according to methods specified in [RFC5148].
Routable Unicast IP Address
A routable unicast IP address is a unicast IP address that when
put into the IP.SourceAddress or IP.DestinationAddress field is
scoped sufficiently to be forwarded by a router. Globally-scoped
unicast IP addresses and Unique Local Addresses (ULAs) [RFC6130]
are examples of routable unicast IP addresses.
Originating Node (OrigNode) Originating Node (OrigNode)
The originating node is the source, its AODVv2 router creates a The originating node is the data source node; if it is not itself
AODVv2 control message on its behalf in an effort to disseminate an AODVv2 router, its AODVv2 router creates a AODVv2 RREQ message
some routing information. The originating node is also referred on its behalf in an effort to flood some routing information. The
to as a particular message's originator. originating node is also referred to as a particular message's
originator.
Target Node (TargetNode)
The TargetNode denotes the ultimate destination of a message.
This Node (ThisNode)
ThisNode denotes the AODVv2 router currently processing an AODVv2
message.
Route Error (RERR) Route Error (RERR)
A RERR message is used to indicate that an AODVv2 router does not A RERR message is used to indicate that an AODVv2 router no longer
have a forwarding route to one or more particular addresses. has a route to one or more particular destinations.
Route Reply (RREP) Route Reply (RREP)
A RREP message is used to disseminate routing information about A RREP message is used to supply routing information about the
the RREP TargetNode to the RREP OrigNode and the AODVv2 routers RREQ TargetNode to the RREQ OrigNode and the AODVv2 routers
between them. between them.
Route Request (RREQ) Route Request (RREQ)
A RREQ message is used to discover a valid route to a particular An AODVv2 router uses a RREQ message to discover a valid route to
destination address, called the RREQ TargetNode. When an AODVv2 a particular destination address, called the RREQ TargetNode.
router processes a RREQ, it learns routing information on how to When an AODVv2 router processes a RREQ, it learns routing
reach the RREQ OrigNode. information on how to reach the RREQ OrigNode.
Target Node (TargetNode)
The TargetNode is the ultimate destination of a message.
This Node (ThisNode)
ThisNode corresponds to the AODVv2 router process currently
performing a calculation or attending to a message.
Type-Length-Value structure (TLV) Type-Length-Value structure (TLV)
A generic way to represent information, please see [RFC5444] for A generic way to represent information as specified in [RFC5444].
additional information.
Unreachable Node (UnreachableNode) Unreachable Node (UnreachableNode)
An UnreachableNode is a node for which a forwarding route is An UnreachableNode is a node for which a forwarding route is
unknown. unknown.
3. Applicability Statement
The AODVv2 routing protocol is designed for stub (i.e., non-transit)
or disconnected (i.e., from the Internet) mobile ad hoc networks
(MANETs). AODVv2 handles a wide variety of mobility patterns by
dynamically determining routes on-demand. AODVv2 also handles a wide
variety of traffic patterns. In networks with a large number of
routers, AODVv2 is best suited for sparse traffic scenarios where any
particular router forwards packets to only a small percentage of the
AODVv2 routers in the network, due to the on-demand nature of route
discovery and route maintenance.
AODVv2 is applicable to memory constrained devices, since little
routing state is maintained in each AODVv2 router. Only routing
information related to routes between active sources and destinations
is maintained, in contrast to proactive routing protocols that
require routing information to all routers within the routing region
be maintained.
AODVv2 supports routers with multiple interfaces. In addition to
routing for their local processes, AODVv2 routers can also route on
behalf of other non-routing nodes (i.e., "hosts"), reachable via
those interfaces. Any such node which is not itself an AODVv2 router
SHOULD NOT be served by more than one AODVv2 router. Although AODVv2
is closely related to AODV [RFC3561], and has some of the features of
DSR [RFC4728], AODVv2 is not interoperable with either of those other
two protocols.
AODVv2 routers perform route discovery to find a route to a
particular destination. Therefore, AODVv2 routers MUST must be
configured to respond to RREQs for a certain set of addresses. When
AODVv2 is the only protocol interacting with the forwarding table,
AODVv2 MAY be configured to perform route discovery for all unknown
unicast destinations.
At all times within an AODVv2 routing region, only one AODVv2 router
SHOULD be serve any routing client. The coordination among multiple
AODVv2 routers to distribute routing information correctly for a
shared address (i.e. an address that is advertised and can be reached
via multiple AODVv2 routers) is not described in this document. The
AODVv2 router operation of shifting responsibility for a routing
client from one AODVv2 router to another is mentioned in Appendix B
Each AODVv2 router, if serving router clients other than itself, is
configured with information about the IP addresses of its clients.
There is no requirement that an AODVv2 router have information about
the router clients of other AODVv2 routers. Address assignment
procedures are entirely out of scope for AODVv2.
AODVv2 only utilizes bidirectional links. In the case of possible
unidirectional links, either blacklists (see Section 5.13.2) or other
means (e.g. adjacency establishment with only neighboring routers
that have bidirectional communication as indicated by NHDP [RFC6130])
of ensuring and monitoring bi-directionality is recommended.
Otherwise, persistent packet loss could occur.
The routing algorithm in AODVv2 may be operated at layers other than
the network layer, using layer-appropriate addresses. The routing
algorithm makes of some persistent state; if there is no persistent
storage available for this state, recovery can exact a performance
penalty in case of AODVv2 router reboots.
4. Data Structures 4. Data Structures
4.1. Route Table Entry 4.1. Route Table Entry
The route table entry is a conceptual data structure. The route table entry is a conceptual data structure.
Implementations may use any internal representation that conforms to Implementations may use any internal representation so long as it
the semantics of a route as specified in this document. provides access to the same information as specified below.
Conceptually, a route table entry has the following fields: Conceptually, a route table entry has the following fields:
Route.Address Route.Address
The (host or network) destination address of the node(s) The (host or network) destination address of the node(s)
associated with the routing table entry. associated with the routing table entry.
Route.Prefix Route.Prefix
Indicates that the associated address is a network address, rather The value is the length of the netmask/prefix. If the value of
than a host address. The value is the length of the netmask/ the Route.Prefix is different than the length of addresses in the
prefix. address family used by the AODVv2 routers, the associated address
is a routing prefix, rather than a host address.
Route.SeqNum Route.SeqNum
The AODVv2 SeqNum associated with this routing information. The AODVv2 SeqNum associated with a route table entry.
Route.NextHopAddress Route.NextHopAddress
The IP address of the adjacent AODVv2 router on the path toward An IP address of the adjacent AODVv2 router on the path toward the
the Route.Address. Route.Address.
Route.NextHopInterface Route.NextHopInterface
The interface used to send packets toward the Route.Address. The interface used to send packets toward the Route.Address.
Route.Forwarding
A flag indicating whether this Route can be used for forwarding
data packets. This flag MAY be provided for management and
monitoring.
Route.Broken Route.Broken
A flag indicating whether this Route is broken. This flag is set A flag indicating whether this Route is broken. This flag is set
to true if the next-hop becomes unreachable or in response to to true if the next-hop becomes unreachable or in response to
attending to a RERR (see Section 5.5.4). processing to a RERR (see Section 5.5.4).
The following field is optional: The following field is optional:
Route.Dist Route.Dist
A dimensionless metric indicating the distance traversed before A dimensionless metric indicating the distance traversed before
reaching the Route.Address node. reaching the Route.Address node.
Not including optional information may cause performance degradation, Not including optional information may cause performance degradation,
but it will not cause the protocol to operate incorrectly. but it will not prohibit the protocol from discovering valid routes.
In addition to a route table data structure, each route table entry In addition to a route table data structure, each route table entry
may have several timers associated with the information. These may have several timers associated with the information. Timers and
timers/timeouts are discussed in Section 5.2.3. timeouts are discussed in Section 5.2.3.
4.2. AODVv2 Messages 4.2. AODVv2 Message Structure and Information Elements
IP Protocol Number 138 (manet) has been reserved for MANET protocols
[RFC5498]. In addition to using this IP protocol number, AODVv2 may
use UDP at destination port 269 (manet) [RFC5498].
AODVv2 messages are transmitted in packets that conform to the
generalized packet and message format as described in [RFC5444].
Here is a brief description of the format.
A packet formatted according to RFC5444 contains zero or more
messages.
A message contains a message header, message TLV block, and zero
or more address blocks.
Each of the address blocks may also have an associated address TLV
block.
All AODVv2 messages SHOULD be sent using the IP protocol number (138)
reserved for manet protocols [RFC5498]; or the UDP destination port
(269) reserved for manet protocols [RFC5498] and IP protocol number
for UDP.
Most AODVv2 messages are sent with the IP destination address set to
the link-local multicast address LL-MANET-Routers [RFC5498] unless
otherwise specified. Therefore, all AODVv2 routers SHOULD subscribe
to LL-MANET-Routers [RFC5498] to receiving AODVv2 messages. Note
that multicast packets MAY be sent via unicast. For example, this
may occur for certain link-types (non broadcast mediums), for
manually configured router adjacencies, or in order to improve
robustness.
When describing AODVv2 protocol messages, it is necessary to refer to When describing AODVv2 protocol messages, it is necessary to refer to
fields in several distinct parts of the overall packet. These fields in several distinct parts of the overall packet. These
locations include the IP header, the UDP header, and fields from locations include the IP header, the UDP header, and fields from
[RFC5444]. This document uses the following notation conventions. [RFC5444]. This document uses the notational conventions found in
Information found in the table. table 1.
+---------------------------+-------------------+ +---------------------------+-------------------+
| Information Location | Notational Prefix | | Information Location | Notational Prefix |
+---------------------------+-------------------+ +---------------------------+-------------------+
| IP header | IP. | | IP header | IP. |
| UDP header | UDP. |
| RFC5444 message header | MsgHdr. | | RFC5444 message header | MsgHdr. |
| RFC5444 message TLV | MsgTLV. | | RFC5444 message TLV | MsgTLV. |
| RFC5444 address blocks | AddBlk. | | RFC5444 address blocks | AddBlk. |
| RFC5444 address block TLV | AddTLV. | | RFC5444 address block TLV | AddTLV. |
+---------------------------+-------------------+ +---------------------------+-------------------+
Table 1 Table 1
4.2.1. Generalized Packet and Message Structure
AODVv2 messages conform to the generalized packet and message format
as described in [RFC5444]. Here is a brief description of the
format. A packet is made up of messages. A message is made up of a
message header, message TLV block, and zero or more address blocks.
Each of the address blocks may also have an associated address TLV
block.
For interoperability with other AODVv2 routers, all AODVv2 messages
specified in this document SHOULD sent using the IP protocol number
(138) reserved for manet protocols [RFC5498]; or the UDP destination
port (269) reserved for manet protocols [RFC5498] and IP protocol
number for UDP.
Most AODVv2 messages are sent with the IP destination address set to
the link-local multicast address LL-MANET-Routers [RFC5498] unless
otherwise stated. Therefore, all AODVv2 routers SHOULD subscribe to
LL-MANET-Routers [RFC5498] for receiving control packets. Note that
multicast packets MAY be sent via unicast. For example, this may
occur for certain link-types (non broadcast mediums), improved
robustness, or manually configured router adjacencies.
Unicast AODVv2 messages (e.g. RREP) unless otherwise specified in
this document are sent with the IP destination set to the
Route.NextHopAddress of the route to the TargetNode.
The IPv4 TTL (IPv6 Hop Limit) field for all packets containing AODVv2 The IPv4 TTL (IPv6 Hop Limit) field for all packets containing AODVv2
messages is set to 255. If a packet is received with a value other messages is set to 255. If a packet is received with a value other
than 255, it is discarded. This mechanism helps to ensures that than 255, any AODVv2 message contained in the packet MUST be ignored
packets have not passed through any intermediate routers, and it is by AODVv2. This mechanism, known as "The Generalized TTL Security
known as GTSM [RFC5082]. Mechanism" (GTSM) [RFC5082] helps to ensure that packets have not
traversed any intermediate routers.
The length of an address (32 bits for IPv4 and 128 bits for IPv6) The length of an address (32 bits for IPv4 and 128 bits for IPv6)
inside an AODVv2 message depends on the msg-addr-length (MAL) in the inside an AODVv2 message depends on the msg-addr-length (MAL) in the
msg-header, as specified in [RFC5444]. msg-header, as specified in [RFC5444].
AODVv2 control packets SHOULD be given priority queuing and channel IP packets containing AODVv2 protocol messages SHOULD be given
access. priority queuing and channel access.
4.2.2. Routing Message (RteMsg) - RREQ and RREP
Routing Messages (RteMsgs) are used to disseminate routing
information. There are two AODVv2 message types that are considered
to be routing messages (RteMsgs): RREQ and RREP. They contain very
similar information and function, but have slightly different
handling rules. The main difference between the two messages is that
RREQ messages generally solicit a RREP, whereas a RREP is the
response to RREQ.
RteMsg creation and handling are described in Section 5.3.
A RteMsg requires the following information: AODVv2 messages require the following information:
IP.SourceAddress IP.SourceAddress
The IP address of the node currently sending this packet. This The IP address of the node currently sending this packet. This
field is generally filled automatically by the operating system field is generally filled automatically by the operating system
and should not require special handling. and should not require special handling.
IP.DestinationAddress IP.DestinationAddress
The IP address of the packet destination. For multicast RREQ the The IP address of the packet destination. For multicast messages
IP.DestinationAddress is set to LL-MANET-Routers [RFC5498]. For the IP.DestinationAddress is set to LL-MANET-Routers [RFC5498].
unicast RREP the IP.DestinationAddress is set to the For unicast messages the IP.DestinationAddress is set to the
NextHopAddress toward the RREP TargetNode. NextHopAddress toward the TargetNode.
IP.ProtocolNumber and UDP.DestinationPort
The IP Protocol Number 138 (manet) has been reserved for MANET
protocols [RFC5498]. In addition to using this IP protocol
number, AODVv2 may use the UDP port 269 (manet) [RFC5498] in
conjunction with the IP Protocol Number 17 (UDP).
MsgHdr.HopLimit MsgHdr.HopLimit
The remaining number of hops this message is allowed to traverse. The remaining number of hops this message is allowed to traverse.
If an AODVv2 message within a RFC 5444 packet has exhausted its
hop limit, then it should be removed from the packet.
4.3. RteMsg-specific Protocol Elements
AODVv2 message types RREQ and RREP are denoted as Routing Messages
(RteMsgs) and used to flood routing information. RREQ and RREP have
similar information and function, but have slightly different
handling rules. The main difference between the two messages is that
RREQ messages are generally broadcast to solicit a RREP, and
conversely a RREP is the unicast response to RREQ. RteMsg creation
and handling are described in Section 5.3.
Unicast AODVv2 RteMsgs (e.g. RREP) unless otherwise specified are
sent with the IP destination set to the Route.NextHopAddress of the
route to the TargetNode.
A RteMsg REQUIRES the following information in addition to the fields
indicated in Section 4.2:
AddBlk.TargetNode.Address AddBlk.TargetNode.Address
The IP address of the message TargetNode. In a RREQ the The IP address of the message TargetNode. In a RREQ the IP
TargetNode is the destination address for which route discovery is address of the message TargetNode is the destination address for
being performed. In a RREP the TargetNode is the RREQ OrigNode which route discovery is being performed. In a RREP the
address. The TargetNode address is the first address in a routing TargetNode is the RREQ OrigNode address. The TargetNode address
message. is the first address in a routing message.
AddBlk.OrigNode.Address AddBlk.OrigNode.Address
The IP address of the originator and its associated prefix length. The IP address of the originator and its associated prefix length.
In a RREQ the OrigNode is the source's address and prefix. In a In a RREQ the OrigNode is the source's address and prefix. In a
RREP the OrigNode is the RREQ TargetNode's address and prefix for RREP the OrigNode is the RREQ TargetNode's address and prefix for
which a RREP is being generated. This address is the second which a RREP is being generated. This address is the second
address in the message for RREQ. address in the message for RREQ.
OrigNode.AddTLV.SeqNum OrigNode.AddTLV.SeqNum
The AODVv2 sequence number of the originator's AODVv2 router. The AODVv2 sequence number of the originator's AODVv2 router.
A RteMsg may optionally include the following information: A RteMsg may optionally include the following information:
TargetNode.AddTLV.SeqNum TargetNode.AddTLV.SeqNum
The last known AODVv2 sequence number of the TargetNode. The last known AODVv2 sequence number of the TargetNode.
TargetNode.AddTLV.Dist
The last known Distance to the TargetNode.
AddBlk.AdditionalNode.Address AddBlk.AdditionalNode.Address
The IP address of an additional node that can be reached via the The IP address of an additional node that can be reached via the
AODVv2 router adding this information. Each AODVv2 router adding this information. Each
AdditionalNode.Address MUST include its prefix. Each AdditionalNode.Address MUST include its prefix. Each
AdditionalNode.Address MUST also have an associated Node.SeqNum in AdditionalNode.Address MUST also have an associated Node.SeqNum in
the address TLV block. the address TLV block.
AdditionalNode.AddTLV.SeqNum AdditionalNode.AddTLV.SeqNum
The AODVv2 sequence number associated with this routing The AODVv2 sequence number associated with this routing
information. information.
skipping to change at page 11, line 44 skipping to change at page 12, line 29
OrigNode.AddTLV.Dist OrigNode.AddTLV.Dist
A metric of the distance to reach the associated OrigNode.Address. A metric of the distance to reach the associated OrigNode.Address.
This field is incremented by at least one at each intermediate This field is incremented by at least one at each intermediate
AODVv2 router. AODVv2 router.
AdditionalNode.AddTLV.Dist AdditionalNode.AddTLV.Dist
A metric of the distance to reach the associated A metric of the distance to reach the associated
AdditionalNode.Address. This field is incremented by at least one AdditionalNode.Address. This field is incremented by at least one
at each intermediate AODVv2 router. at each intermediate AODVv2 router.
4.2.3. Route Error (RERR) 4.4. Route Error (RERR)-specific Protocol Elements
A RERR message is used to disseminate the information that a route is A RERR message is used to flood the information that a route is not
not available for one or more particular addresses. available for one or more particular addresses.
RERR creation and handling are described in Section 5.5. RERR creation and handling are described in Section 5.5.
A RERR requires the following information: A RERR requires the following information in addition to the field
indicated in Section 4.2:
IP.SourceAddress
The IP address of the AODVv2 router that sent this packet. This
field is generally filled automatically by the operating system
and should not require special handling.
IP.DestinationAddress
For multicast RERR messages, The IP address is set to LL-MANET-
Routers [RFC5498]. For unicast RERR messages, the IP address is
set to the NextHopAddress.
IP.ProtocolNumber and UDP.DestinationPort
The IP Protocol Number 138 (manet) has been reserved for MANET
protocols [RFC5498]. In addition to using this IP protocol
number, AODVv2 may use the UDP port 269 (manet) [RFC5498] in
conjunction with the IP Protocol Number 17 (UDP).
MsgHdr.HopLimit
The remaining number of hops this message is allowed to traverse.
AddBlk.UnreachableNode.Address AddBlk.UnreachableNode.Address
The address of an UnreachableNode and its associated prefix The address of an UnreachableNode and its associated prefix
length. Multiple unreachable addresses may be included in a RERR. length. Multiple unreachable addresses may be included in a RERR.
A Route Error may optionally include the following information: A Route Error may optionally include the following information:
UnreachableNode.AddTLV.SeqNum UnreachableNode.AddTLV.SeqNum
The last known AODVv2 sequence number of the unreachable node. If The last known AODVv2 sequence number of the unreachable node. If
a SeqNum for an address is zero (0) or not included, it is assumed a SeqNum for an address is zero (0) or not included, it is assumed
to be unknown. This case occurs when a node receives a message to to be unknown. This case occurs when a node receives a message to
forward to a destination for which it does not have any forward to a destination for which it does not have any
information in its routing table. information in its routing table.
5. Detailed Operation 5. Detailed Operation for the Base Protocol
5.1. AODVv2 Sequence Numbers 5.1. AODVv2 Sequence Numbers
AODVv2 sequence numbers allow AODVv2 routers to judge the freshness AODVv2 sequence numbers allow AODVv2 routers to judge the freshness
of routing information and ensure loop freedom. of routing information and consequently ensure loop freedom.
5.1.1. Maintaining A Node's Own Sequence Number 5.1.1. Maintaining A Node's Own Sequence Number
AODVv2 requires that each AODVv2 router in the network maintain its AODVv2 requires that each AODVv2 router in the network maintain its
own AODVv2 sequence number (OwnSeqNum) on behalf of the addresses for own AODVv2 sequence number (OwnSeqNum). OwnSeqNum a 16-bit unsigned
which it is responsible. OwnSeqNum a 16-bit unsigned integer. The integer. An AODVv2 router increments its OwnSeqNum under the
circumstances for ThisNode to increment its OwnSeqNum are described circumstances described in Section 5.3.
in Section 5.3.
5.1.2. Numerical Operations on OwnSeqNum
When ThisNode increments its OwnSeqNum it MUST do so by treating the
sequence number value as an unsigned number.
5.1.3. OwnSeqNum Rollover
Incrementing an OwnSeqNum whose value is the largest largest possible Incrementing an OwnSeqNum whose value is the largest largest possible
number representable as a 16-bit unsigned integer (i.e., 65,535), number representable as a 16-bit unsigned integer (i.e., 65,535),
SHOULD be set to one (1). In other words, the sequence number after MUST be set to one (1). In other words, the sequence number after
65,535 is 1. 65,535 is 1.
5.1.4. Actions After OwnSeqNum Loss 5.1.2. Actions After OwnSeqNum Loss
An AODVv2 router SHOULD maintain its sequence number in persistent An AODVv2 router SHOULD maintain its own sequence number in
storage. persistent storage.
If an AODVv2 router's OwnSeqNum is lost, it MUST take certain actions If an AODVv2 router's OwnSeqNum is lost, it MUST take certain actions
to avoid creating routing loops. To prevent this possibility after to avoid creating routing loops. To prevent this possibility after
OwnSeqNum loss an AODVv2 router MUST wait for at least OwnSeqNum loss an AODVv2 router MUST wait for at least
ROUTE_DELETE_TIMEOUT before fully participating in the AODVv2 routing ROUTE_DELETE_TIMEOUT before fully participating in the AODVv2 routing
protocol. If an AODVv2 control message is received during this protocol. If an AODVv2 protocol message is received during this
waiting period, the AODVv2 router SHOULD handle it normally but MUST waiting period, the AODVv2 router SHOULD perform normal route table
NOT transmit or retransmit any AODVv2 messages. If a data packet is entry updates but MUST NOT transmit or retransmit any AODVv2 RREQ or
received for forwarding to another destination during this waiting RREP messages. If a data packet is received for forwarding to
period, the AODVv2 router MUST generate a RERR message indicating another destination during this waiting period, the AODVv2 router
that this route is not available and reset its waiting timeout. At MUST transmit a RERR message indicating that this route is not
the end of the waiting period the AODVv2 router sets its OwnSeqNum to available and reset its waiting timeout. At the end of the waiting
one (1) and begins participating. period the AODVv2 router sets its OwnSeqNum to one (1) and begin
participating.
The longest a node need wait is ROUTE_SEQNUM_AGE_MAX_TIMEOUT. At the The longest a node need wait is ROUTE_SEQNUM_AGE_MAX_TIMEOUT. At the
end of the maximum waiting period a node SHOULD set its OwnSeqNum to end of the maximum waiting period a node SHOULD set its OwnSeqNum to
one (1) and begins participating. one (1) and begins participating.
5.2. AODVv2 Routing Table Operations 5.2. AODVv2 Routing Table Operations
5.2.1. Judging Routing Information's Usefulness 5.2.1. Judging Routing Information's Usefulness
Given a route table entry (Route.SeqNum, Route.Dist, and Given a route table entry (Route.SeqNum, Route.Dist, and
Route.Broken) and new incoming routing information for a particular Route.Broken) and incoming routing information for a particular
node in a RteMsg (Node.SeqNum, Node.Dist, and RteMsg message type - destination in a RteMsg (Node.SeqNum, Node.Dist, and RteMsg message
RREQ/RREP), the quality of the new routing information is evaluated type - RREQ/RREP), the incoming routing information is classified as
to determine its usefulness. Incoming routing information is follows:
classified as follows:
1. Stale
If Node.SeqNum - Route.SeqNum < 0 (using signed 16-bit arithmetic)
the incoming information is stale. Using stale routing
information is not allowed, since doing so might result in routing
loops.
(Node.SeqNum - Route.SeqNum < 0) 1. Stale (Node.SeqNum < Route.SeqNum)
using signed 16-bit arithmetic If Node.SeqNum < Route.SeqNum (using signed 16-bit arithmetic) the
incoming information is stale. Using stale routing information is
not allowed, since that might result in routing loops.
2. Loop-possible 2. Not safe against loops
If Node.SeqNum == Route.SeqNum the incoming information may cause If Node.SeqNum == Route.SeqNum, additional information MUST be
loops if used; in this case additional information MUST be examined. If Route.Dist or Node.Dist is unknown or zero (0), or
examined. If Route.Dist or Node.Dist is unknown or zero (0), then if Node.Dist > Route.Dist + 1, then the incoming information is
the routing information is loop-possible. If Node.Dist > not guaranteed to prevent routing loops. Using such incoming
Route.Dist + 1, then the routing information is loop-possible. routing information is not allowed. The following pseudocode is
Using loop-possible routing information is not allowed, otherwise offered to indicate the logical condition under which the incoming
routing loops may be formed. information is not guaranteed to protect against loops.
(Node.SeqNum == Route.SeqNum) AND (Node.SeqNum == Route.SeqNum) AND
((Node.Dist is unknown) OR ((Node.Dist > Route.Dist + 1) OR
(Route.Dist is unknown) OR (Route.Dist is unknown) OR (Node.Dist is unknown))
(Node.Dist > Route.Dist + 1))
3. Disfavored or equivalent 3. Offers no improvement
In case of known equal SeqNum, the information is disfavored in In case of known equal SeqNum, the information is considered worse
multiple cases: (case i) if Node.Dist == Route.Dist + 1 (it is a than the existing route table information in multiple cases: (case
greater distance route) AND Route.Broken == false; (case ii) if i) if Node.Dist > Route.Dist (it is a more expensive route) AND
Node.Dist == Route.Dist (equal distance route) AND Route.Broken == Route.Broken == false; (case ii) if Node.Dist == Route.Dist (equal
false AND this RteMsg is a RREQ. This condition reduces the distance route) AND Route.Broken == false AND this RteMsg is a
number of RREQ flooded by stopping forwarding of RREQ with RREQ. Such RREQs offer no improvement and SHOULD NOT be
equivalent distance. retransmitted. Updating route table entries using such incoming
routing information is not allowed.
((Node.SeqNum == Route.SeqNum) AND ((Node.SeqNum == Route.SeqNum) AND
(((Node.Dist == Route.Dist + 1) AND (Route.Broken == false)) OR (((Node.Dist > Route.Dist) AND (Route.Broken == false)) OR
((Node.Dist == Route.Dist) AND ((Node.Dist == Route.Dist) AND
(RteMsg is RREQ) AND (Route.Broken == false)))) (RteMsg is RREQ) AND (Route.Broken == false))))
4. Preferable 4. Offers improvement
Incoming routing information that does not match any of the above Incoming routing information that does not match any of the above
criteria is loop-free and better than the information existing in criteria is loop-free and better than the existing routing table
the routing table. Information is always preferable if information. We provide the following pseudo-code to determine
Node.SeqNum - Route.SeqNum > 0 (using signed 16-bit arithmetic). whether incoming routing information should be used to update an
In the case of equal sequence numbers, the information is existing route table entry.
preferable in multiple cases: (case i) if Node.Dist < Route.Dist;
(case ii) if Node.Dist == Route.Dist + 1 AND Route.Broken == true
(a broken route is being repaired); (case iii) if Node.Dist ==
Route.Dist AND it is a RREP (RREP with equal distance are
forwarded) OR Route.Broken == true (a broken route is being
repaired). For completeness, we provide the following (optimized)
pseudo-code.
(Node.SeqNum - Route.SeqNum > 0) OR (/* signed 16-bit arithmetic */ Node.SeqNum - Route.SeqNum > 0) OR
using signed 16-bit arithmetic
((Node.SeqNum == Route.SeqNum) AND ((Node.SeqNum == Route.SeqNum) AND
((Node.Dist < Route.Dist) OR [(Node.Dist < Route.Dist) OR
((Node.Dist == Route.Dist + 1) AND (Route.Broken == true)) OR ((Route.Broken == true) AND (Node.Dist <= Route.Dist + 1)) OR
((Node.Dist == Route.Dist) AND ((RteMsg is RREP) AND (Node.Dist == Route.Dist)]
((RteMsg is RREP) OR (Route.Broken == true)))))
5.2.2. Creating or Updating a Route Table Entry with Received 5.2.2. Creating or Updating Route Table Entries
Preferable Routing Information
The route table entry is populated with the following information: Each route table entry is populated with the following information:
1. the Route.Address is set to Node.Address, 1. the Route.Address is set to Node.Address,
2. the Route.Prefix is set to the Node.Prefix. 2. the Route.Prefix is set to the Node.Prefix.
3. the Route.SeqNum is set to the Node.SeqNum, 3. the Route.SeqNum is set to the Node.SeqNum,
4. the Route.NextHopAddress is set to the node that transmitted this 4. the Route.NextHopAddress is set to the IP.SourceAddress (i.e., an
AODVv2 RteMsg packet (i.e., the IP.SourceAddress), address of the node that last transmitted the RteMsg packet)
5. the Route.NextHopInterface is set to the interface that this 5. the Route.NextHopInterface is set to the interface on which the
AODVv2 packet was received on, incoming AODVv2 packet was received,
6. the Route.Broken flag is set to false, 6. the Route.Broken flag is set to false,
7. if known, the Route.Dist is set to the Node.Dist, 7. if known, the Route.Dist is set to the Node.Dist,
Fields without known values are not populated with any value.
The timer for the minimum delete timeout (ROUTE_AGE_MIN) is set to The timer for the minimum delete timeout (ROUTE_AGE_MIN) is set to
ROUTE_AGE_MIN_TIMEOUT. The timer for the maximum delete timeout ROUTE_AGE_MIN_TIMEOUT. The timer for the maximum delete timeout
(ROUTE_SEQNUM_AGE_MAX) is set to Node.AddTLV.VALIDITY_TIME [RFC5497] (ROUTE_SEQNUM_AGE_MAX) is set to Node.AddTLV.VALIDITY_TIME [RFC5497]
if included; otherwise, ROUTE_SEQNUM_AGE_MAX is set to if included; otherwise, ROUTE_SEQNUM_AGE_MAX is set to
ROUTE_SEQNUM_AGE_MAX_TIMEOUT. The usage of these timers and others ROUTE_SEQNUM_AGE_MAX_TIMEOUT. The usage of these timers and others
are described in Section 5.2.3. are described in Section 5.2.3.
At this point, a forwarding route has been created and the With these assignments to the route table entry, a route has been
Route.Forwarding flag set. Afterward, the route can be used to send created and the Route.Forwarding flag set. Afterward, the route can
any queued data packets and forward any incoming data packets for be used to send any buffered data packets and to forward any incoming
Route.Address. This route also fulfills any outstanding route data packets for Route.Address. This route also fulfills any
discovery attempts for Node.Address. outstanding route discovery (RREQ) attempts for Node.Address.
5.2.3. Route Table Entry Timeouts 5.2.3. Route Table Entry Timeouts
5.2.3.1. Minimum Delete Timeout (ROUTE_AGE_MIN) 5.2.3.1. Minimum Delete Timeout (ROUTE_AGE_MIN)
When an AODVv2 router transmits a RteMsg, other AODVv2 routers expect When an AODVv2 router transmits a RteMsg, other AODVv2 routers expect
the transmitting AODVv2 router to have a forwarding route to the the transmitting AODVv2 router to have a forwarding route to the
RteMsg originator. After updating a route table entry, it SHOULD be RteMsg originator. A route table entry SHOULD be kept in the route
maintained for at least ROUTE_AGE_MIN. Failure to maintain the table for at least ROUTE_AGE_MIN after it has been updated. Failure
information might result in lost messages/packets, or in the worst to maintain the route table entry might result in lost messages/
case scenario several duplicate messages. packets, or several duplicate messages.
After the ROUTE_AGE_MIN timeout a route can safely be deleted. After the ROUTE_AGE_MIN timeout a route can safely be deleted.
5.2.3.2. Maximum Sequence Number Delete Timeout (ROUTE_SEQNUM_AGE_MAX) 5.2.3.2. Maximum Sequence Number Delete Timeout (ROUTE_SEQNUM_AGE_MAX)
Sequence number information is time sensitive, and MUST be deleted Sequence number information for route table entries is time
after a time in order to ensure loop-free routing. sensitive, and MUST be deleted after a time in order to ensure loop-
free routing.
After the ROUTE_SEQNUM_AGE_MAX timeout a route's sequence number After the ROUTE_SEQNUM_AGE_MAX timeout a route's sequence number
information MUST be discarded. information MUST be discarded.
5.2.3.3. Recently Used Timeout (ROUTE_USED) 5.2.3.3. Recently Used Timeout (ROUTE_USED)
When a route is used to forward data packets, this timer is set to When a route is used to forward data packets, this timer is set to
expire after ROUTE_USED_TIMEOUT. This operation is also discussed in expire after ROUTE_USED_TIMEOUT, as discussed in Section 5.5.2.
Section 5.5.2.
If a route has not been used recently, then a timer for ROUTE_DELETE If a route has not been used recently, then a timer for ROUTE_DELETE
is set to ROUTE_DELETE_TIMEOUT. is set to ROUTE_DELETE_TIMEOUT.
5.2.3.4. Delete Information Timeout (ROUTE_DELETE) 5.2.3.4. Delete Information Timeout (ROUTE_DELETE)
As time progresses the likelihood that old routing information is As time progresses the likelihood that old routing information is
useful decreases, especially if the network nodes are mobile. useful decreases, especially if the network nodes are mobile.
Therefore, old information SHOULD be deleted. Therefore, old information SHOULD be deleted.
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exist. exist.
If a previous value of the TargetNode.SeqNum is known (from a routing If a previous value of the TargetNode.SeqNum is known (from a routing
table entry using longest-prefix matching), it SHOULD be placed in table entry using longest-prefix matching), it SHOULD be placed in
TargetNode.AddTLV.SeqNum in all but the last RREQ attempt. If a TargetNode.AddTLV.SeqNum in all but the last RREQ attempt. If a
TargetNode.SeqNum is not included, it is assumed to be unknown by TargetNode.SeqNum is not included, it is assumed to be unknown by
handling nodes. This operation ensures that no intermediate AODVv2 handling nodes. This operation ensures that no intermediate AODVv2
routers reply, and ensures that the TargetNode's AODVv2 router routers reply, and ensures that the TargetNode's AODVv2 router
increments its sequence number. increments its sequence number.
Next, the node adds AddBlk.OrigNode.Address, its prefix, and the Next, ThisNode adds AddBlk.OrigNode.Address, its prefix, and the
OrigNode.AddTLV.SeqNum (OwnSeqNum) to the RteMsg. OrigNode.AddTLV.SeqNum (OwnSeqNum) to the RteMsg.
The OrigNode.Address is the address of the source for which this The OrigNode.Address is the address of the source for which this
AODVv2 router is initiating this route discovery. The AODVv2 router is initiating this route discovery. The
OrigNode.Address MUST be a unicast address. This information will be OrigNode.Address MUST be a unicast address. This information will be
used by nodes to create a route toward the OrigNode, enabling used by nodes to create a route toward the OrigNode, enabling
delivery of a RREP, and eventually used for proper forwarding of data delivery of a RREP, and eventually used for proper forwarding of data
packets. packets.
If OrigNode.Dist is included it is set to a number greater than zero If OrigNode.Dist is included it is set to a number, greater than zero
(0). (0), representing the distance between OrigNode and ThisNode.
The MsgHdr.HopLimit SHOULD be set to MSG_HOPLIMIT. The MsgHdr.HopLimit SHOULD be set to MSG_HOPLIMIT.
For RREQ, the MsgHdr.HopLimit MAY be set in accordance with an
expanding ring search as described in [RFC3561] to limit the RREQ
propagation to a subset of the local network and possibly reduce
route discovery overhead.
The IP.DestinationAddress for multicast RREQ is set to LL-MANET-
Routers. For links that do not support multicast or situations in
which unicast messaging is preferred, the IP.DestinationAddress for
unicast RREQ is set to the NextHopAddress.
5.3.2. RREP Creation 5.3.2. RREP Creation
First, the AddBlk.TargetNode.Address is added to the RREP. The First, the AddBlk.TargetNode.Address is added to the RREP. The
TargetNode is the ultimate destination of this RREP; the RREQ TargetNode is the ultimate destination of this RREP; the RREQ
OrigNode.Address. OrigNode.Address.
Next, AddBlk.OrigNode.Address and prefix are added to the RREP. The Next, AddBlk.OrigNode.Address and prefix are added to the RREP. The
AddBlk.OrigNode.Address is the RREQ TargetNode.Address. The AddBlk.OrigNode.Address is the RREQ TargetNode.Address. The
AddBlk.OrigNode.Address MUST be a unicast IP address. ThisNode AddBlk.OrigNode.Address MUST be a unicast IP address. ThisNode
SHOULD advertise the largest known prefix containing SHOULD advertise the largest known prefix containing
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If OwnSeqNum is not incremented the routing information might be If OwnSeqNum is not incremented the routing information might be
considered stale. In this case, the RREP might not reach the RREP considered stale. In this case, the RREP might not reach the RREP
Target. Target.
After any of the sequence number operations above, the RREP After any of the sequence number operations above, the RREP
OrigNode.AddTLV.SeqNum (OwnSeqNum) MUST also be added to the RREP. OrigNode.AddTLV.SeqNum (OwnSeqNum) MUST also be added to the RREP.
Other AddTLVs in the RREP for the OrigNode and TargetNode SHOULD be Other AddTLVs in the RREP for the OrigNode and TargetNode SHOULD be
included and set accordingly. If OrigNode.Dist is included it is set included and set accordingly. If OrigNode.Dist is included it is set
to a number greater than zero (0) and less than or equal to 65,535. to a number greater than zero (0) and less than or equal to 254. The
The Distance value will influence judgment of the routing information Distance value will influence judgment of the routing information
(Section 5.2.1) against known information at other AODVv2 routers (Section 5.2.1) against known information at other AODVv2 routers
that handle this RteMsg. that handle this RteMsg.
The MsgHdr.HopLimit is set to MSG_HOPLIMIT. The MsgHdr.HopLimit is set to MSG_HOPLIMIT.
The IP.DestinationAddress for RREP is set to the IP address of the The IP.DestinationAddress for RREP is set to the IP address of the
Route.NextHopAddress for the route to the RREP TargetNode. Route.NextHopAddress for the route to the RREP TargetNode.
5.3.3. RteMsg Handling 5.3.3. RteMsg Handling
First, ThisNode examines the RteMsg to ensure that it contains the First, ThisNode examines the RteMsg to ensure that it contains the
required information: MsgHdr.HopLimit, AddBlk.TargetNode.Address, required information: MsgHdr.HopLimit, AddBlk.TargetNode.Address,
AddBlk.OrigNode.Address, and OrigNode.AddTLV.SeqNum. If the required AddBlk.OrigNode.Address, and OrigNode.AddTLV.SeqNum. If the required
information do not exist, the message is discarded and further information does not exist, the message is discarded and further
processing stopped. processing stopped.
Next, ThisNode MAY selectively attend to messages based upon ThisNode MUST only handle AODVv2 messages from adjacent routers.
information in the message. ThisNode SHOULD only handle messages
from adjacent AODVv2 routers. If ThisNode chooses not to handle this
message, the message is discarded and further processing stopped.
ThisNode checks if the AddBlk.OrigNode.Address is a valid multihop- ThisNode checks if the AddBlk.OrigNode.Address is a valid routable
capable (e.g. site or global scope) unicast address. If the address unicast address. If not, the message is ignored and further
is not a valid unicast address, the message is discarded and further
processing stopped. processing stopped.
ThisNode also checks whether AddBlk.OrigNode.Address is an address ThisNode also checks whether AddBlk.OrigNode.Address is an address
handled by this AODVv2 router. If this node is the originating handled by this AODVv2 router. If this node is the originating
AODVv2 router, the RteMsg is dropped. AODVv2 router, the RteMsg is dropped.
ThisNode checks if the AddBlk.TargetNode.Address is a valid multihop- ThisNode checks if the AddBlk.TargetNode.Address is a valid routable
capable unicast address. If the address is not a valid unicast unicast address. If the address is not a valid unicast address, the
address, the message is discarded and further processing stopped. message is discarded and further processing stopped.
Next, ThisNode checks whether its routing table has an entry to the Next, ThisNode checks whether its routing table has an entry to the
AddBlk.OrigNode.Address using longest-prefix matching [RFC1812]. If AddBlk.OrigNode.Address using longest-prefix matching [RFC1812]. If
a route with a valid Route.SeqNum does not exist, then the new a route with a valid Route.SeqNum does not exist, then the new
routing information is considered preferable and a new route table routing information is used to create a new route table entry is
entry is created and updated as described in Section 5.2.2. If a created and updated as described in Section 5.2.2. If a route table
route table entry does exists and it has a known Route.SeqNum, the entry does exists and it has a known Route.SeqNum, the incoming
incoming routing information is compared with the route table entry routing information is compared with the route table entry following
following the procedure described in Section 5.2.1. If the incoming the procedure described in Section 5.2.1. If the incoming routing
routing information is considered preferable, the route table entry information is considered preferable, the route table entry is
is updated as described in Section 5.2.2. updated as described in Section 5.2.2.
For each address (except the TargetNode) in the RteMsg that includes
AddTLV.Dist information, the AddTLV.Dist information MAY be
incremented. If the resulting Distance value for the OrigNode is
greater than 65,535, the message is discarded. If the resulting
Distance value for another node is greater than 65,535, the
associated address and its information are removed from the RteMsg.
The updated Distance value will influence judgment of the routing
information (Section 5.2.1).
After handling the OrigNode's routing information, then each address
that is not the TargetNode MAY be considered for creating and
updating routes. Creating and updating routes to other nodes can
eliminate RREQ for those IP destinations, in the event that data
needs to be forwarded to the IP destination(s) now or in the near
future.
For each of the additional addresses considered, ThisNode first
checks the that the address is a multihop-capable unicast address.
If the address is not a unicast address, the address and all related
information MUST be removed.
If the routing table does not have a matching route with a known
Route.SeqNum for this additional address using longest-prefix
matching, then a route is created and updated as described in
Section 5.2.2. If a route table entry exists with a known
Route.SeqNum, the incoming routing information is compared with the
route table entry following the procedure described in Section 5.2.1.
If the incoming routing information is considered preferable, the
route table entry is updated as described in Section 5.2.2.
If the routing information for an AdditionalNode.Address is not
considered preferable, then it is removed from the RteMsg. Removing
this information ensures that the information is not propagated.
At this point, if the routing information for the OrigNode was not At this point, if the routing information for the OrigNode was not
preferable then this RteMsg SHOULD be discarded and no further preferable then this RteMsg SHOULD be discarded and no further
processing of this message SHOULD be performed. processing of this message SHOULD be performed.
If the ThisNode is the AODVv2 router responsible for the TargetNode If the TargetNode is a router client of ThisNode this RteMsg is a
and this RteMsg is a RREQ, then ThisNode responds with a RREP to the RREQ, then ThisNode responds with a RREP to the RREQ OrigNode (the
RREQ OrigNode (the new RREP's TargetNode). The procedure for issuing new RREP's TargetNode). The procedure for issuing a new RREP is
a new RREP is described in Section 5.3.2. At this point, ThisNode described in Section 5.3.2. Afterwards, ThisNode need not perform
need not perform any more operations for the RteMsg being processed. any more operations for the RteMsg being processed.
As an alternative to issuing a RREP, ThisNode MAY choose to As an alternative to issuing a RREP, ThisNode MAY choose to
distribute routing information about ThisNode (the RREQ TargetNode) distribute routing information about ThisNode (the RREQ TargetNode)
more widely. That is, ThisNode MAY optionally perform a route more widely. That is, ThisNode MAY optionally perform a route
discovery; by issuing a RREQ with ThisNode listed as the TargetNode, discovery by issuing a RREQ with ThisNode listed as the TargetNode,
using the procedure in Section 5.3.1. At this point, ThisNode need using the procedure in Section 5.3.1. At this point, ThisNode need
not perform any more operations for the RteMsg being processed. not perform any more operations for the RteMsg being processed.
If the resulting Distance value for the OrigNode is greater than For each address (except the TargetNode) in the RteMsg that includes
65,535, the message is discarded. If the resulting Distance value AddTLV.Dist information, the AddTLV.Dist information is incremented
for another node is greater than 65,535, the associated address and by at least one (1). The updated Distance value will influence
its information are removed from the RteMsg. judgment of the routing information (Section 5.2.1) against known
information at other AODVv2 routers that handle this RteMsg.
Next, the MsgHdr.HopLimit is decremented by one (1). If this If the resulting Distance value for the OrigNode is greater than 254,
RteMsg's MsgHdr.HopLimit is greater than or equal to one (1), the message is discarded. If the resulting Distance value for
ThisNode is not the TargetNode, AND this RteMsg is a RREQ, then the another node is greater than 254, the associated address and its
current RteMsg (altered by the procedure defined above) SHOULD be information are removed from the RteMsg. If the MsgHdr.HopLimit is
sent to the IP.DestinationAddress LL-MANET-Routers [RFC5498]. If the equal to one (1), then the message is discarded. Otherwise, the
RREQ is unicast, the IP.DestinationAddress is set to the MsgHdr.HopLimit is decremented by one (1).
If ThisNode is not the TargetNode, AND this RteMsg is a RREQ, then
the current RteMsg (as altered by the procedure defined above) SHOULD
be sent to the IP multicast address LL-MANET-Routers [RFC5498]. If
the RREQ is unicast, the IP.DestinationAddress is set to the
NextHopAddress. NextHopAddress.
If this RteMsg's MsgHdr.HopLimit is greater than or equal to one (1), If ThisNode is not the TargetNode, AND this RteMsg is a RREP, then
ThisNode is not the TargetNode, AND this RteMsg is a RREP, then the the current RteMsg is sent to the Route.NextHopAddress for the RREP's
current RteMsg is sent to the Route.NextHopAddress for the RREP's
TargetNode.Address. If no forwarding route exists to TargetNode.Address. If no forwarding route exists to
TargetNode.Address, then a RERR SHOULD be issued to the OrigNode of TargetNode.Address, then a RERR SHOULD be issued to the OrigNode of
the RREP. the RREP.
By sending the updated RteMsg, ThisNode advertises that it will route By sending the updated RteMsg, ThisNode advertises that it will route
for addresses contained in the outgoing RteMsg based on the for addresses contained in the outgoing RteMsg based on the
information enclosed. ThisNode MAY choose not to send the RteMsg, information enclosed. ThisNode MAY choose not to send the RteMsg,
though not resending this RteMsg could decrease connectivity in the though not resending this RteMsg could decrease connectivity in the
network or result in a non-shortest distance path. network or result in a non-shortest distance path.
Some examples of why ThisNode might choose to not re-issue a RteMsg The circumstances under which ThisNode might choose to not re-issue a
are: if ThisNode does not want to advertise routing for the contained RteMsg are not specified in this document. Some examples might
addresses because it is already heavily loaded; if ThisNode has include the following:
already issued nearly identical routing information (e.g. ThisNode
had recently issued a RteMsg with nearly the same distance); or if o if ThisNode does not want to advertise routing for the contained
ThisNode is low on energy and does not want to expend energy for addresses because it is already heavily loaded
control message sending or packet forwarding. The exact
circumstances producing such behavior are not specified in this o if ThisNode has already issued identical routing information (e.g.
document. ThisNode had recently issued a RteMsg with the same distance)
o if ThisNode is low on energy and does not want to expend energy
for protocol message sending or packet forwarding
5.4. Route Discovery 5.4. Route Discovery
When a source's AODVv2 router needs to forward a data packet on When an AODVv2 router needs to forward a data packet and it does not
behalf of an attached node and it does not have a forwarding route to have a forwarding route to the destination address, it sends a RREQ
the data packet's unicast IP destination address, ThisNode sends a (described in Section 5.3.1) to discover a route to the particular
RREQ (described in Section 5.3.1) to discover a route to the destination (TargetNode).
particular destination (TargetNode).
After issuing a RREQ, the OrigNode AODVv2 router waits for a route to After issuing a RREQ, the AODVv2 router (OrigNode) waits for a RREP
be created to the TargetNode. If a route is not created within indicating the next hop for a route to the TargetNode. If a route is
RREQ_WAIT_TIME, ThisNode may again try to discover a route by issuing not created within RREQ_WAIT_TIME, OrigNode may again try to discover
another RREQ using the procedure defined in Section 5.3.1 again. a route by issuing another RREQ using the procedure defined in
Route discovery SHOULD be considered failed after Section 5.3.1 again. Route discovery SHOULD be considered to have
DISCOVERY_ATTEMPTS_MAX and the final RREQ's corresponding failed after DISCOVERY_ATTEMPTS_MAX and the corresponding wait time
RREQ_WAIT_TIME. for a response to the final RREQ.
To reduce congestion in a network, repeated attempts at route To reduce congestion in a network, repeated attempts at route
discovery for a particular TargetNode SHOULD utilize an exponential discovery for a particular TargetNode SHOULD utilize an binary
backoff. exponential backoff.
For example, the first time an AODVv2 router issues a RREQ, it waits
RREQ_WAIT_TIME for a route to the TargetNode. If a route is not
found within that time, the AODVv2 router MAY send another RREQ. If
a route is not found within two (2) times the current waiting time,
another RREQ MAY be sent. No more than DISCOVERY_ATTEMPTS_MAX route
discovery attempts SHOULD be made before considering route discovery
for this destination to have failed. For each additional attempt,
the waiting time for the previous RREQ is multiplied by two (2) so
that the waiting time conforms to a binary exponential backoff.
Data packets awaiting a route SHOULD be buffered by the source's Data packets awaiting a route SHOULD be buffered by the source's
AODVv2 router. This buffer SHOULD have a fixed limited size AODVv2 router. This buffer SHOULD have a fixed limited size
(BUFFER_SIZE_PACKETS or BUFFER_SIZE_BYTES) and older data packets (BUFFER_SIZE_PACKETS or BUFFER_SIZE_BYTES). Determining which
SHOULD be discarded first. packets to discard first is a matter of policy at each AODVv2 router;
in the absence of policy constraints, by default older data packets
Buffering of data packets can have both positive and negative SHOULD be discarded first. Buffering of data packets can have both
effects, and therefore buffer settings (BUFFER_DURING_DISCOVERY) positive and negative effects, and therefore settings for buffering
SHOULD be administratively configurable or intelligently controlled. (BUFFER_DURING_DISCOVERY) SHOULD be administratively configurable.
Nodes without sufficient memory available for buffering may be
configured with BUFFER_DURING_DISCOVERY = FALSE; this will affect the
latency required for launching TCP applications to new destinations.
If a route discovery attempt has failed (i.e. an attempt or multiple If a route discovery attempt has failed (i.e. an attempt or multiple
attempts have been made without receiving a RREP) to find a route to attempts have been made without receiving a RREP) to find a route to
the TargetNode, any data packets buffered for the corresponding the TargetNode, any data packets buffered for the corresponding
TargetNode are dropped and a Destination Unreachable ICMP message TargetNode MUST BE dropped and a Destination Unreachable ICMP message
SHOULD be delivered to the source. (Type 3) SHOULD be delivered to the source of the data packet. The
code for the ICMP message is 1 (Host unreachable error). If the
AODVv2 router is not the source (OrigNode), then the ICMP is sent
over the interface from which the source sent the packet to the
AODVv2 router.
5.5. Route Maintenance 5.5. Route Maintenance
A RERR SHOULD be issued if a data packet is to be forwarded and it A RERR SHOULD be issued if a data packet is to be forwarded and it
cannot be delivered to the next-hop because no forwarding route for cannot be delivered to the next-hop because no forwarding route for
the IP.DestinationAddress exists; RERR generation is described in the IP.DestinationAddress exists; RERR generation is described in
Section 5.5.3. Section 5.5.3.
Upon this condition, an ICMP Destination Unreachable message SHOULD Upon this condition, an ICMP Destination Unreachable message SHOULD
NOT be generated unless this router is responsible for the NOT be generated unless this router is responsible for the
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In addition to inability to forward a data packet, a RERR SHOULD be In addition to inability to forward a data packet, a RERR SHOULD be
issued immediately after detecting a broken link (see Section 5.5.1) issued immediately after detecting a broken link (see Section 5.5.1)
of a forwarding route to quickly notify AODVv2 routers that certain of a forwarding route to quickly notify AODVv2 routers that certain
routes are no longer available. If a newly unavailable route has not routes are no longer available. If a newly unavailable route has not
been used recently (indicated by ROUTE_USED), the RERR SHOULD NOT be been used recently (indicated by ROUTE_USED), the RERR SHOULD NOT be
generated. generated.
5.5.1. Active Next-hop Router Adjacency Monitoring 5.5.1. Active Next-hop Router Adjacency Monitoring
Nodes MUST monitor connectivity to adjacent next-hop AODVv2 routers Nodes SHOULD monitor connectivity to adjacent next-hop AODVv2 routers
on forwarding routes. This monitoring can be accomplished by one or on forwarding routes. This monitoring can be accomplished by one or
several mechanisms, including: several mechanisms, including:
o Neighborhood discovery [I-D.ietf-manet-nhdp] o Neighborhood discovery [RFC6130]
o Route timeout o Route timeout
o Lower layer feedback that a particular adjacent router is no o Lower layer trigger that a neighboring router is no longer
longer reachable reachable
o Other monitoring mechanisms or heuristics o Other monitoring mechanisms or heuristics
Upon determining that a next-hop AODVv2 router is unreachable, Upon determining that a next-hop AODVv2 router has become
ThisNode MUST remove the affected forwarding routes (those with an unreachable, ThisNode MUST remove the affected forwarding routes
unreachable next-hop) and unset the Route.Forwarding flag. ThisNode (those using the unreachable next-hop) and unset the Route.Forwarding
also flags the associated routes in AODVv2's routing table as Broken. flag. ThisNode also flags the associated routes in AODVv2's routing
For each broken route the timer for ROUTE_DELETE is set to table as Broken. For each broken route the timer for ROUTE_DELETE is
ROUTE_DELETE_TIMEOUT. set to ROUTE_DELETE_TIMEOUT.
5.5.2. Updating Route Lifetimes During Packet Forwarding 5.5.2. Updating Route Lifetimes During Packet Forwarding
To avoid removing the forwarding route to reach the IP.SourceAddress, To avoid removing the forwarding route to reach an IP.SourceAddress,
ThisNode SHOULD set the "ROUTE_USED" timeout to the value ThisNode SHOULD set the "ROUTE_USED" timeout to the value
ROUTE_USED_TIMEOUT for the route to the IP.SourceAddress upon ROUTE_USED_TIMEOUT for the route to that IP.SourceAddress upon
receiving a data packet. If the timer for ROUTE_DELETE is set, it is receiving a data packet or an AODVv2 message. If the timer for
removed. ROUTE_DELETE is set, that timer is removed. The Route.Broken flag is
unset.
To avoid removing the forwarding route to the IP.DestinationAddress To avoid removing the forwarding route to the IP.DestinationAddress
that is being used, ThisNode SHOULD set the "ROUTE_USED" timeout to that is being used, ThisNode SHOULD set the "ROUTE_USED" timeout to
the value ROUTE_USED_TIMEOUT for the route to the the value ROUTE_USED_TIMEOUT for the route to the
IP.DestinationAddress upon sending a data packet. If the timer for IP.DestinationAddress upon sending a data packet or an AODVv2
ROUTE_DELETE is set, it is removed. message. If the timer for ROUTE_DELETE is set, it is removed. The
Route.Broken flag is unset.
5.5.3. RERR Generation 5.5.3. RERR Generation
A RERR informs AODVv2 routers that a route to certain destinations is When an AODVv2 router receives a packet (from PrevHopAddress), and
not available through ThisNode. the router (ThisNode) does not have a route available for the
destination of the packet, ThisNode uses an RERR message is used to
inform one or more neighboring AODVv2 routers that its route to the
packet destination is no longer available.
When creating a new RERR, the address of the first UnreachableNode When ThisNode creates a new RERR, the address of the first
(IP.DestinationAddress from a data packet or RREP.TargetNode.Address) UnreachableNode (IP.DestinationAddress from a data packet or
is inserted into an Address Block AddBlk.UnreachableNode.Address. If RREP.TargetNode.Address) is inserted into an Address Block
a prefix is known for the UnreachableNode.Address, it SHOULD be AddBlk.UnreachableNode.Address. If a prefix is known for the
included. Otherwise, the UnreachableNode.Address is assumed to be a UnreachableNode.Address, it SHOULD be included. Otherwise, the
host address with a full length prefix. If a value for the UnreachableNode.Address is assumed to be a host address with a full
UnreachableNode's SeqNum (UnreachableNode.AddTLV.SeqNum) is known, it length prefix. If a value for the UnreachableNode's SeqNum
SHOULD be placed in the RERR. The MsgHdr.HopLimit is set to (UnreachableNode.AddTLV.SeqNum) is known, it SHOULD be placed in the
MSG_HOPLIMIT. RERR. The MsgHdr.HopLimit SHOULD be set to MSG_HOPLIMIT.
If SeqNum information is not known or not included in the RERR, all If SeqNum information is not known or not included in the RERR, all
nodes handling the RERR will assume their routing information nodes handling the RERR will assume their routing information
associated with the UnreachableNode is no longer valid and flag those associated with the UnreachableNode is no longer valid and flag those
routes as broken. routes as broken.
A multicast RERR is sent to the IP.DestinationAddress LL-MANET- A RERR MAY be sent to the multicast address LL-MANET-Routers
Routers [RFC5498]. Sending the RERR to the LL-MANET-Routers address [RFC5498], thus notifying all nearby AODVv2 routers that might depend
notifies all nearby AODVv2 routers that might depend on the now on the now broken link. If the RERR is unicast, the
broken link. If the RERR is unicast, the IP.DestinationAddress is IP.DestinationAddress is set to the PrevHopAddress.
set to the NextHopAddress.
At this point, the packet or message that forced generation of this After sending the RERR, ThisNode SHOULD discard the packet or message
RERR SHOULD be discarded. that triggered generation of the RERR.
5.5.4. RERR Handling 5.5.4. RERR Handling
First, ThisNode examines the RteMsg to ensure that it contains the First, ThisNode examines the incoming RERR to ensure that it contains
required information: MsgHdr.HopLimit and MsgHdr.HopLimit and AddBlk.UnreachableNode.Address. If the required
AddBlk.UnreachableNode.Address. If the required information do not information does not exist, the incoming RERR message is discarded
exist, the message is discarded and further processing stopped. and further processing stopped.
Next, ThisNode MAY selectively handle messages based upon information
in the message. ThisNode MAY choose to only handle messages from
adjacent AODVv2 routers. If ThisNode chooses not to handle this
message, the message is discarded and further processing stopped.
When an AODVv2 router handles a RERR, it examines each When an AODVv2 router handles a RERR, it examines the information for
UnreachableNode's information. The attending AODVv2 router removes each UnreachableNode. The AODVv2 router removes the forwarding
the forwarding route, unsets the Route.Forwarding flag, sets the route, unsets the Route.Forwarding flag, sets the Route.Broken flag,
Route.Broken flag, and the timer for ROUTE_DELETE is set to and the timer for ROUTE_DELETE is set to ROUTE_DELETE_TIMEOUT for
ROUTE_DELETE_TIMEOUT for each UnreachableNode.Address found using each UnreachableNode.Address found using longest prefix matching that
longest prefix matching that meets all of the following conditions: meets all of the following conditions:
1. The UnreachableNode.Address is a multihop-capable unicast 1. The UnreachableNode.Address is a routable unicast address.
address.
2. The Route.NextHopAddress is the same as the RERR 2. The Route.NextHopAddress is the same as the RERR
IP.SourceAddress. IP.SourceAddress.
3. The Route.NextHopInterface is the same as the interface on which 3. The Route.NextHopInterface is the same as the interface on which
the RERR was received. the RERR was received.
4. The Route.SeqNum is zero (0), unknown, OR the 4. The Route.SeqNum is zero (0), unknown, OR the
UnreachableNode.SeqNum is zero (0), unknown, OR Route.SeqNum - UnreachableNode.SeqNum is zero (0), unknown, OR Route.SeqNum -
UnreachableNode.SeqNum <= 0 (using signed 16-bit arithmetic). UnreachableNode.SeqNum <= 0 (using signed 16-bit arithmetic).
During handling if Route.SeqNum is zero (0) or unknown and If Route.SeqNum is zero (0) or unknown and UnreachableNode.SeqNum
UnreachableNode.SeqNum exists in the RERR and is not zero (0), then exists in the RERR and is not zero (0), then Route.SeqNum SHOULD be
Route.SeqNum MAY be set to UnreachableNode.SeqNum. Setting set to UnreachableNode.SeqNum. Setting Route.SeqNum can reduce
Route.SeqNum can reduce future RERR handling and forwarding. future RERR handling and forwarding.
Each UnreachableNode that did not result in a broken route is removed Each UnreachableNode that did not result in marking a route table
from the RERR, since propagation of this information will not result entry as broken route is removed from the RERR, since propagation of
in any benefit. such information will not result in any benefit.
Each UnreachableNode that did result in a broken route SHOULD remain Each UnreachableNode that did indicate a broken route SHOULD remain
in the RERR. in the RERR.
If any UnreachableNode was removed, all other information (AddTLVs) If any UnreachableNode was removed, all other information (AddTLVs)
associated with the removed address(es) MUST also be removed. associated with the UnreachableNode address(es) MUST also be removed.
After handling if Route.SeqNum is known and an UnreachableNode.SeqNum If Route.SeqNum is known and an UnreachableNode.SeqNum is not
is not included in the RERR, then Route.SeqNum (i.e. included in the RERR, then Route.SeqNum (i.e.
UnreachableNode.SeqNum) MAY be added to the RERR. Including UnreachableNode.SeqNum) MAY be included with the RERR. Including
UnreachableNode.SeqNum can reduce future RERR handling and UnreachableNode.SeqNum can reduce future RERR handling and
forwarding. forwarding.
If no UnreachableNode addresses remain in the RERR, no other handling If no UnreachableNode addresses remain in the RERR, or if the
is required and the RERR is discarded. MsgHdr.HopLimit is equal to one (1), then the RERR MUST be discarded.
If handling continues, the MsgHdr.HopLimit is decremented by one (1).
Further, if this RERR's new MsgHdr.HopLimit is greater than one (1)
and at least one unreachable node address remains in the RERR, then
the updated RERR SHOULD be sent.
A multicast RERR is sent to the IP.DestinationAddress LL-MANET- Otherwise, the MsgHdr.HopLimit is decremented by one (1). The RERR
Routers [RFC5498]. If the RERR is unicast, the IP.DestinationAddress SHOULD be sent to the multicast address LL-MANET-Routers [RFC5498].
is set to the NextHopAddress. Alternatively, if the RERR is unicast, the IP.DestinationAddress is
set to the PrevHopAddress.
5.6. Unknown Message and TLV Types 5.6. Unknown Message and TLV Types
If a message with an unknown type is received, the message is If a message with an unknown type is received, the message is
discarded. ignored.
For handling of messages that contain unknown TLV types, the default For handling of messages that contain unknown TLV types, ignore the
behavior is to leave the information in control messages unmodified. information for processing, preserve it unmodified for forwarding.
Although, this behavior (UNKNOWN_TYPES) MAY be administratively
controlled.
5.7. Advertising Network Addresses 5.7. Advertising Network Addresses
AODVv2 routers specify the prefix length for each advertised address. AODVv2 routers MAY specify a prefix length for each advertised
Any nodes (other than the advertising AODVv2 router) within the address. Any nodes (other than the advertising AODVv2 router) within
advertised prefix MUST NOT participate in the AODVv2 protocol the advertised prefix MUST NOT participate in the AODVv2 protocol
directly. For example, advertising 192.0.2.1 with a prefix length of directly. For example, advertising 192.0.2.1 with a prefix length of
24 indicates that all nodes with the matching 192.0.2.X are reachable 24 indicates that all nodes with the matching 192.0.2.X are reachable
through this AODVv2 router. through this AODVv2 router. An AODVv2 router MUST NOT advertise
network addresses unless it can guarantee its ability for forwarding
packets to any host address within the address range of the
corresponding network.
5.8. Simple Internet Attachment 5.8. Simple Internet Attachment
Simple Internet attachment consists of a stub network of AODVv2 Simple Internet attachment consists of a stub (i.e., non-transit)
routers connected to the Internet via a single Internet AODVv2 router network of AODVv2 routers connected to the Internet via a single
(IDR). Internet AODVv2 router (IAR).
AODVv2 routers, and hosts behind these routers, wishing to be
reachable from hosts on the Internet MUST have IP addresses within
the IDR's routable and topologically correct prefix (e.g.
192.0.2.0/24). As in any Internet-attached network, AODVv2 routers, and hosts behind
these routers, wishing to be reachable from hosts on the Internet
MUST have IP addresses within the IAR's routable and topologically
correct prefix (e.g. 192.0.2.0/24).
The IDR is responsible for generating RREQ to find nodes within the The IAR is responsible for generating RREQ to find nodes within the
AODVv2 Region on behalf of nodes on the Internet, as well as AODVv2 Region on behalf of nodes on the Internet, as well as
responding to route requests from the AODVv2 region on behalf of the responding to route requests from the AODVv2 region on behalf of the
nodes on the Internet. nodes on the Internet.
/--------------------------\ /--------------------------\
/ Internet \ / Internet \
\ / \ /
\------------+-------------/ \------------+-------------/
| |
Routable & | Routable & |
Topologically | Topologically |
Correct | Correct |
Prefix | Prefix |
+-----+------+ +-----+--------+
| Internet | | Internet |
/------| AODVv2 |-------\ /------| AODVv2 |-------\
/ | Router | \ / | Router | \
/ |192.0.2.1/32| \ / |192.0.2.1/32 | \
| |Responsible | | | |Responsible | |
| | for | | | | for | |
| |AODVv2 Region | | | |AODVv2 Region | |
| |192.0.2.0/24| | | |192.0.2.0/24 | |
| +------------+ | | +--------------+ |
| +--------------+ | | +----------------+ |
| | AODVv2 Router | | | | AODVv2 Router | |
| | 192.0.2.2/32 | | | | 192.0.2.2/32 | |
| +--------------+ | | +----------------+ |
| +--------------+ | | +----------------+ |
| | AODVv2 Router | | | | AODVv2 Router | |
| | 192.0.2.3/32 | | | | 192.0.2.3/32 | |
\ +--------------+ / \ +----------------+ /
\ / \ /
\---------------------------/ \-----------------------------/
Figure 1: Simple Internet Attachment Example Figure 1: Simple Internet Attachment Example
When an AODVv2 router within the AODVv2 Region wants to discover a When an AODVv2 router within the AODVv2 Region wants to discover a
route to a node on the Internet, it uses the normal AODVv2 route route to a node on the Internet, it uses the normal AODVv2 route
discovery for that IP Destination Address. The IDR is responsible discovery for that IP Destination Address. The IAR MUST respond to
for properly responding to RREQ on behalf of the Internet RREQ on behalf of the Internet destination.
destination.
When a packet from a node on the Internet destined for a node in the When a packet from a node on the Internet destined for a node in the
AODVv2 region reaches the IDR, if the IDR does not have a route to AODVv2 region reaches the IAR, if the IAR does not have a route to
that destination it will perform normal AODVv2 route discovery for that destination it will perform normal AODVv2 route discovery for
that destination. that destination.
5.9. Multiple Interfaces 5.9. Multiple Interfaces
AODVv2 may be used with multiple interfaces; therefore, the AODVv2 may be used with multiple interfaces; therefore, the
particular interface over which packets arrive MUST be known whenever particular interface over which packets arrive MUST be known whenever
a packet is received. Whenever a new route is created, the interface a packet is received. Whenever a new route is created, the interface
through which the Route.Address can be reached is also recorded in through which the Route.Address can be reached is also recorded in
the route table entry. the route table entry.
When multiple interfaces are available, a node transmitting a When multiple interfaces are available, a node transmitting a
multicast packet with IP.DestinationAddress set to LL-MANET-Routers multicast packet with IP.DestinationAddress set to LL-MANET-Routers
SHOULD send the packet on all interfaces that have been configured SHOULD send the packet on all interfaces that have been configured
for AODVv2 operation. for AODVv2 operation.
Similarly, AODVv2 routers should subscribe to LL-MANET-Routers on all Similarly, AODVv2 routers SHOULD subscribe to LL-MANET-Routers on all
their AODVv2 interfaces. their AODVv2 interfaces.
5.10. AODVv2 Control Packet/Message Generation Limits 5.10. AODVv2 Control Packet/Message Generation Limits
To ensure predictable control overhead, AODVv2 router's rate of To ensure predictable messaging overhead, AODVv2 router's rate of
packet/message generation SHOULD be limited. The rate and algorithm packet/message generation SHOULD be limited. The rate and algorithm
for limiting messages (CONTROL_TRAFFIC_LIMITS) is left to the for limiting messages (CONTROL_TRAFFIC_LIMITS) is left to the
implementor and should be administratively configurable or implementor and should be administratively configurable. AODVv2
intelligently controlled. AODVv2 control messages SHOULD be messages SHOULD be discarded in the following order of preference:
discarded in the following order of preference: RREQ, RREP, and RREQ, RREP, and finally RERR.
finally RERR.
6. Administratively Configured Parameters and Timer Values 5.11. Optional Features
Several optional features of AODVv2, and associated with AODV, are
not required by minimal implementations. These features are expected
to be useful in networks with greater mobility, or larger node
populations, or requiring shorter latency for application launches.
The optional features are as follows:
o Expanding Rings Multicast
o Intermediate RREPs (iRREPs): Without iRREP, only the destination
can respond to a RREQ.
o Precursor lists.
o Reporting Multiple Unreachable Nodes. An RERR message can carry
more than one Unreachable Destination node for cases when a single
link breakage causes multiple destinations to become unreachable
from an intermediate router.
5.11.1. Expanding Rings Multicast
For multicast RREQ, the MsgHdr.HopLimit MAY be set in accordance with
an expanding ring search as described in [RFC3561] to limit the RREQ
propagation to a subset of the local network and possibly reduce
route discovery overhead.
5.11.2. Intermediate RREP
This specification has been published as a separate Internet Draft .
5.11.3. Precursor Notification
The Dynamic MANET On-demand (AODVv2) routing protocol is intended for
use by mobile routers in wireless, multihop networks. AODVv2
determines unicast routes among AODVv2 routers within the network in
an on-demand fashion, offering on-demand convergence in dynamic
topologies. This document specifies a simple modification to AODVv2
(and possibly other reactive routing protocols) enabling faster
notifications to known sources of traffic upon determination that a
route for such traffic's destination has become Broken.
5.11.3.1. Overview
If an AODVv2 router, while attempting to forward a packet to a
particular destination, determines that the next hop (one of its
neighbors) is no longer reachable, AODVv2 specifies that the router
notify the source of that packet that the route to the destination
has become Broken. In the existing specification, the notification
to the source is a unicast RERR message.
However, in many cases there will be several sources of of traffic
for that particular destination. In fact, the broken link for the
next hop in question may be a path component of numerous other routes
for other destinations, and in that case the node detecting the
broken link must mark as Broken multiple routes, one for each of the
newly unreachable destinations. Each route that uses the newly
broken link is no longer valid. For each such route, every node
along the way from the source using that route, to the node detecting
the broken link, is known as a "precursor" for the broken next hop.
All the precursors for a particular next hop should be notified about
the change in status of their route to a destination downstream from
the broken next hop.
5.11.3.2. Precursor Notification
During normal operation, each node wishing to enable the improved
notification for precursors of any links to its next hop neighbors
has to keep track of the precursors. This is done by maintaining a
precursor table and updating the table whenever the node initiates or
relays a RREP message back to a node originating a RREQ message.
When the node transmits the RREP message, it is implicitly agreeing
to forward traffic from the RREQ originator towards the RREP
originator (i.e., along the next hop link to the neighbor from which
the RREP was received). The "other" next hop, which is the neighbor
along the way towards the originator of the RREQ message, is then the
next precursor for the route towards the destination requested by the
RREQ.
Each such precursor should then be recorded as a precursor for a
route along the next hop. The same next hop may be in service for
routes to multiple destinations, but for precursor list management it
is only important to keep track of precursors for a particular next
hop; the exact destination does not matter, only the particular next
hop towards the destination(s).
When a node observes that one of its neighbors is no longer
reachable, the node first checks to see whether the link to that
neighbor is a next hop for any more distant destination in its route
table. If not, then the node simply updates any relevant neighorhood
information and takes no further action.
Otherwise, for all destinations no longer reachable because of the
changed status of the next hop, the node first checks to see whether
the link to that neighbor is a next hop for any more distant
destination in its route table. If not, then the node simply updates
any relevant neighorhood information and takes no further action.
For each precursor of the next hop, the node MAY notify the precursor
in one of three ways:
o unicast RERR
o broadcast RERR
o multicast RERR to multicast group PRECURSOR_RERR_RECEIVERS
Each precursor then MAY execute the same procedure until all affected
traffic sources have received the RERR route maintenance information.
When a precursor receives a unicast RERR, the precursor MUST further
unicast the RERR message towards the affected traffic source. If a
precursor receives a broadcast or multicast RERR, the precursor MAY
further retransmit the RERR towards the traffic source.
5.11.4. Reporting Multiple Unreachable Nodes
5.11.5. Message Aggregation
The aggregation of multiple messages into a packet is not specified
in this document, but if aggregation does occur the IP.SourceAddress
and IP.DestinationAddress of all contained messages MUST be the same.
Implementations MAY choose to temporarily delay transmission of
messages for the purpose of aggregation (into a single packet) or to
improve performance by using jitter [RFC5148].
5.11.6. Adding Additional Routing Information to a RteMsg
DSR [RFC4728] includes source routes as part of the data of its RREPs
and RREQs. Doign so allows additional topology information to be
flooded along with the RteMsg, and potentially allows updating for
stale routing information at MANET routers along new paths between
source and destination. To maintain this functionality, AODVv2 has
defined a somewhat more general method that enables inclusion of
source routes in RteMsgs.
Appending routing information can alleviate route discovery attempts
to the nodes whose information is included, if other AODVv2 routers
use this information to update their routing tables.
Note that, since the initial merger of DSR with AODV to create this
protocol, further experimentation has shown that including the
additional routing information is not always helpful. Sometimes it
seems to help, and other times it seems to reduct overall
performance.
AODVv2 routers can append routing information to a RteMsg. This is
controllable by an option (APPEND_INFORMATION) which SHOULD be
administratively configurable or controlled according to the traffic
characteristics of the network.
Prior to appending an address controlled by this AODVv2 router to a
RteMsg, ThisNode MAY increment its OwnSeqNum as defined in
Section 5.1. If OwnSeqNum is not incremented the appended routing
information might not be considered preferable, when received by
nodes with existing routing information. Incrementation of the
sequence number when appending information to a RteMsg in transit
(APPEND_INFORMATION_SEQNUM) SHOULD be administratively configurable.
Note that, during handling of this RteMsg OwnSeqNum may have already
been incremented; and in this case OwnSeqNum need not be incremented
again.
If an address controlled by this AODVv2 router includes
ThisNode.Dist, it is set to a number greater than zero (0).
For added addresses (and their prefixes) not controlled by this
AODVv2 router, Route.Dist can be included if known.
The VALIDITY_TIME of routing information for appended address(es)
MUST be included, to inform routers about when to delete this
information. The VALIDITY_TIME TLV is defined in Section 5.13.3.
Additional information (e.g. SeqNum and Dist) about any appended
address(es) SHOULD be included.
Note that the routing information about the TargetNode MUST NOT be
added. Also, duplicate address entries SHOULD NOT be added.
Instead, only the best routing information (Section 5.2.1) for a
particular address SHOULD be included.
Intermediate nodes obey the following procedures when processing
AddBlk.AdditionalNode.Address information and other associated TLVs
that are included with a RteMsg. For each address (except the
TargetNode) in the RteMsg that includes AddTLV.Dist information, the
AddTLV.Dist information MUST be incremented. If the resulting
Distance value for the OrigNode is greater than 254, the message is
discarded. If the resulting Distance value for another node is
greater than 254, the associated address and its information are
removed from the RteMsg.
After handling the OrigNode's routing information, then each address
that is not the TargetNode MAY be considered for creating and
updating routes. Creating and updating routes to other nodes can
eliminate RREQ for those IP destinations, in the event that data
needs to be forwarded to the IP destination(s) now or in the near
future.
For each of the additional addresses considered, ThisNode first
checks that the address is a routable unicast address. If the
address is not a unicast address, then the address and all related
information MUST be removed.
If the routing table does not have a matching route with a known
Route.SeqNum for this additional address using longest-prefix
matching, then a route MAY be created and updated as described in
Section 5.2.2. If a route table entry exists with a known
Route.SeqNum, the incoming routing information is compared with the
route table entry following the procedure described in Section 5.2.1.
If the incoming routing information is used, the route table entry
SHOULD be updated as described in Section 5.2.2.
If the routing information for an AdditionalNode.Address is not used,
then it is removed from the RteMsg.
5.12. Administratively Configured Parameters and Timer Values
AODVv2 contains several parameters which MUST be administratively AODVv2 contains several parameters which MUST be administratively
configured. The list of these follows: configured. The list of these follows:
Required Administratively Configured Parameters Required Administratively Configured Parameters
+------------------------+------------------------------------------+ +------------------------+------------------------------------------+
| Name | Description | | Name | Description |
+------------------------+------------------------------------------+ +------------------------+------------------------------------------+
| RESPONSIBLE_ADDRESSES | List of addresses or routing prefixes, | | RESPONSIBLE_ADDRESSES | List of addresses or routing prefixes, |
skipping to change at page 28, line 16 skipping to change at page 31, line 31
AODVv2 contains a number of timers. The default timing parameter AODVv2 contains a number of timers. The default timing parameter
values follow: values follow:
Default Timing Parameter Values Default Timing Parameter Values
+------------------------------+-------------------+ +------------------------------+-------------------+
| Name | Value | | Name | Value |
+------------------------------+-------------------+ +------------------------------+-------------------+
| ROUTE_TIMEOUT | 5 seconds | | ROUTE_TIMEOUT | 5 seconds |
| ROUTE_AGE_MIN_TIMEOUT | 1 second | | ROUTE_AGE_MIN_TIMEOUT | 1 second |
| ROUTE_SEQNUM_AGE_MAX_TIMEOUT | 60 seconds | | ROUTE_SEQNUM_AGE_MAX_TIMEOUT | 600 seconds |
| ROUTE_USED_TIMEOUT | ROUTE_TIMEOUT | | ROUTE_USED_TIMEOUT | ROUTE_TIMEOUT |
| ROUTE_DELETE_TIMEOUT | 2 * ROUTE_TIMEOUT | | ROUTE_DELETE_TIMEOUT | 2 * ROUTE_TIMEOUT |
| ROUTE_RREQ_WAIT_TIME | 2 seconds | | ROUTE_RREQ_WAIT_TIME | 2 seconds |
| UNICAST_MESSAGE_SENT_TIMEOUT | 1 second | | UNICAST_MESSAGE_SENT_TIMEOUT | 1 second |
+------------------------------+-------------------+ +------------------------------+-------------------+
Table 3 Table 3
The above timing parameter values work well for small and medium The above timing parameter values work well for small and medium
well-connected networks with moderate topology changes. well-connected networks with moderate topology changes.
skipping to change at page 28, line 40 skipping to change at page 32, line 10
topology changes the AODVv2 parameters should be adjusted using topology changes the AODVv2 parameters should be adjusted using
either experimentally determined values or dynamic adaptation. For either experimentally determined values or dynamic adaptation. For
example, in networks with infrequent topology changes example, in networks with infrequent topology changes
ROUTE_USED_TIMEOUT may be set to a much larger value. ROUTE_USED_TIMEOUT may be set to a much larger value.
Default Parameter Values Default Parameter Values
+------------------------+-------+----------------------------------+ +------------------------+-------+----------------------------------+
| Name | Value | Description | | Name | Value | Description |
+------------------------+-------+----------------------------------+ +------------------------+-------+----------------------------------+
| MSG_HOPLIMIT | 10 | This value MUST be larger than | | MSG_HOPLIMIT | 20 | This value MUST be larger than |
| | hops | the AODVv2 network diameter. | | | hops | the AODVv2 network diameter. |
| | | Otherwise, routing messages may | | | | Otherwise, routing messages may |
| | | not reach their intended | | | | not reach their intended |
| | | destinations. | | | | destinations. |
| DISCOVERY_ATTEMPTS_MAX | 3 | The number of route discovery | | DISCOVERY_ATTEMPTS_MAX | 3 | The number of route discovery |
| | | attempts to make before | | | | attempts to make before |
| | | indicating that a particular | | | | indicating that a particular |
| | | address is not reachable. | | | | address is not reachable. |
+------------------------+-------+----------------------------------+ +------------------------+-------+----------------------------------+
Table 4 Table 4
In addition to the above parameters and timing values, several In addition to the above parameters and timing values, several
administrative options exist. These options have no influence on administrative options exist. These options have no influence on
correct routing behavior, although they may potentially reduce AODVv2 correct routing behavior, although they may potentially reduce AODVv2
routing control messaging in certain situations. The default protocol messaging in certain situations. The default behavior is to
behavior is to NOT enable any of these options; and although many of NOT enable any of these options; and although many of these options
these options can be administratively controlled, they may be better can be administratively controlled, they may be better served by
served by intelligent control. The following table enumerates intelligent control. The following table enumerates several of the
several of the options. options.
Administratively Controlled Options Administratively Controlled Options
+-------------------------+-----------------------------------------+ +--------------------------+----------------------------------------+
| Name | Description | | Name | Description |
+-------------------------+-----------------------------------------+ +--------------------------+----------------------------------------+
| BUFFER_DURING_DISCOVERY | Whether and how much data to buffer | | BUFFER_DURING_DISCOVERY | Whether and how much data to buffer |
| | during route discovery. | | | during route discovery. |
| UNKNOWN_TYPES | What action to take when an unknown TLV | | APPEND_EXTRA_UNREACHABLE | Whether to append additional |
| | type is received. The default action | | | Unreachable information to RERR. |
| | is to forward this information | | CONTROL_TRAFFIC_LIMITS | AODVv2 messaging SHOULD be limited to |
| | unmodified. Another action would be to | | | avoid consuming all the network |
| | remove this information. | | | bandwidth. |
| CONTROL_TRAFFIC_LIMITS | AODVv2 control messaging SHOULD be | +--------------------------+----------------------------------------+
| | limited to avoid consuming all the |
| | network bandwidth. |
+-------------------------+-----------------------------------------+
Table 5 Table 5
Note: several fields have limited size (bits or bytes) these sizes Note: several fields have limited size (bits or bytes) these sizes
and their encoding may place specific limitations on the values that and their encoding may place specific limitations on the values that
can be set. For example, MsgHdr.HopLimit is a 8-bit field and can be set. For example, MsgHdr.HopLimit is a 8-bit field and
therefore MSG_HOPLIMIT cannot be larger than 255. therefore MSG_HOPLIMIT cannot be larger than 255.
7. IANA Considerations 5.13. IANA Considerations
In its default mode of operation, AODVv2 uses the UDP port MANET In its default mode of operation, AODVv2 uses the UDP port 269
[RFC5498] to carry protocol packets. AODVv2 also uses the link-local [RFC5498] to carry protocol packets. AODVv2 also uses the link-local
multicast address LL-MANET-Routers [RFC5498]. multicast address LL-MANET-Routers [RFC5498].
This section specifies several message types, message tlv-types, and This section specifies several message types, message tlv-types, and
address tlv-types. address tlv-types.
7.1. AODVv2 Message Types Specification 5.13.1. AODVv2 Message Types Specification
AODVv2 Message Types AODVv2 Message Types
+------------------------+----------+ +------------------------+----------+
| Name | Type | | Name | Type |
+------------------------+----------+ +------------------------+----------+
| Route Request (RREQ) | 10 - TBD | | Route Request (RREQ) | 10 - TBD |
| Route Reply (RREP) | 11 - TBD | | Route Reply (RREP) | 11 - TBD |
| Route Error (RERR) | 12 - TBD | | Route Error (RERR) | 12 - TBD |
+------------------------+----------+ +------------------------+----------+
Table 6 Table 6
7.2. Message and Address Block TLV Type Specification 5.13.2. Message and Address Block TLV Type Specification
Message TLV Types Message TLV Types
+-------------------+------+--------+-------------------------------+ +-------------------+------+--------+-------------------------------+
| Name | Type | Length | Value | | Name | Type | Length | Value |
+-------------------+------+--------+-------------------------------+ +-------------------+------+--------+-------------------------------+
| Unicast Response | 10 - | 0 | Indicates to the processing | | Unicast Response | 10 - | 0 | Indicates to the processing |
| Request | TBD | octets | node that the previous hop | | Request | TBD | octets | node that the previous hop |
| | | | (IP.SourceAddress) expects a | | | | | (IP.SourceAddress) expects a |
| | | | unicast message within | | | | | unicast reply message within |
| | | | UNICAST_MESSAGE_SENT_TIMEOUT. | | | | | UNICAST_MESSAGE_SENT_TIMEOUT. |
| | | | Any unicast packet will serve | | | | | Any unicast packet will serve |
| | | | this purpose, and it MAY be | | | | | this purpose, and it MAY be |
| | | | an ICMP REPLY message. If a | | | | | an ICMP REPLY message. If |
| | | | message is not sent, then the | | | | | the reply is not received, |
| | | | previous hop can assume that | | | | | then the previous hop can |
| | | | the link is unidirectional | | | | | assume that the link is |
| | | | and MAY blacklist the link to | | | | | unidirectional and MAY |
| | | | this node. | | | | | blacklist the link to this |
| | | | node. |
+-------------------+------+--------+-------------------------------+ +-------------------+------+--------+-------------------------------+
Table 7 Table 7
7.3. Address Block TLV Specification 5.13.3. Address Block TLV Specification
Address Block TLV Types Address Block TLV Types
+----------------+------------+----------+--------------------------+ +----------------+------------+----------+--------------------------+
| Name | Type | Length | Value | | Name | Type | Length | Value |
+----------------+------------+----------+--------------------------+ +----------------+------------+----------+--------------------------+
| AODVv2 | 10 - TBD | up to 2 | The AODVv2 sequence num | | AODVv2 | 10 - TBD | up to 2 | The AODVv2 sequence num |
| Sequence | | octets | associated with this | | Sequence | | octets | associated with this |
| Number | | | address. The sequence | | Number | | | address. The sequence |
| (AODVv2SeqNum) | | | number may be the last | | (AODVv2SeqNum) | | | number may be the last |
skipping to change at page 31, line 31 skipping to change at page 34, line 31
| VALIDITY_TIME | 1[RFC5497] | | The maximum amount of | | VALIDITY_TIME | 1[RFC5497] | | The maximum amount of |
| | | | time that information | | | | | time that information |
| | | | can be maintained before | | | | | can be maintained before |
| | | | being deleted. The | | | | | being deleted. The |
| | | | VALIDITY_TIME TLV is | | | | | VALIDITY_TIME TLV is |
| | | | defined in [RFC5497]. | | | | | defined in [RFC5497]. |
+----------------+------------+----------+--------------------------+ +----------------+------------+----------+--------------------------+
Table 8 Table 8
8. Security Considerations 5.14. Security Considerations
The objective of the AODVv2 protocol is for each router to The objective of the AODVv2 protocol is for each router to
communicate reachability information to addresses for which it is communicate reachability information to addresses for which it is
responsible. Positive routing information (i.e. a route exists) is responsible. Positive routing information (i.e. a route exists) is
distributed via RteMsgs and negative routing information (i.e. a distributed via RteMsgs and negative routing information (i.e. a
route does not exist) via RERRs. AODVv2 routers that handle these route does not exist) via RERRs. AODVv2 routers that handle these
messages store the contained information to properly forward data messages store the contained information to properly forward data
packets, and they generally provide this information to other AODVv2 packets, and they generally provide this information to other AODVv2
routers. routers.
skipping to change at page 32, line 17 skipping to change at page 35, line 16
A digital signature could be used to identify the source of AODVv2 A digital signature could be used to identify the source of AODVv2
messages and information, along with its authenticity. A nonce or messages and information, along with its authenticity. A nonce or
timestamp SHOULD also be used to protect against replay attacks. timestamp SHOULD also be used to protect against replay attacks.
S/MIME and OpenPGP are two authentication/integrity protocols that S/MIME and OpenPGP are two authentication/integrity protocols that
could be adapted for this purpose. could be adapted for this purpose.
In situations where confidentiality of AODVv2 messages is important, In situations where confidentiality of AODVv2 messages is important,
cryptographic techniques can be applied. cryptographic techniques can be applied.
In certain situations, like sending a RREP or RERR, an AODVv2 router In certain situations, for example sending a RREP or RERR, an AODVv2
could include proof that it has previously received valid routing router could include proof that it has previously received valid
information to reach the destination, at one point of time in the routing information to reach the destination, at one point of time in
past. In situations where routers are suspected of transmitting the past. In situations where routers are suspected of transmitting
maliciously erroneous information, the original routing information maliciously erroneous information, the original routing information
along with its security credentials SHOULD be included. along with its security credentials SHOULD be included.
Note that if multicast is used, any confidentiality and integrity Note that if multicast is used, any confidentiality and integrity
algorithms used must permit multiple receivers to handle the message. algorithms used MUST permit multiple receivers to handle the message.
9. Acknowledgments Routing protocols, however, are prime targets for impersonation
attacks. In networks where the node membership is not known, it is
difficult to determine the occurrence of impersonation attacks, and
security prevention techniques are difficult at best. However, when
the network membership is known and there is a danger of such
attacks, AODVv2 messages must be protected by the use of
authentication techniques, such as those involving generation of
unforgeable and cryptographically strong message digests or digital
signatures. While AODVv2 does not place restrictions on the
authentication mechanism used for this purpose, IPsec Authentication
Message (AH) is an appropriate choice for cases where the nodes share
an appropriate security association that enables the use of AH.
In particular, routing messages SHOULD be authenticated to avoid
creation of spurious routes to a destination. Otherwise, an attacker
could masquerade as that destination and maliciously deny service to
the destination and/or maliciously inspect and consume traffic
intended for delivery to the destination. RERR messages SHOULD be
authenticated in order to prevent malicious nodes from disrupting
active routes between communicating nodes.
If the mobile nodes in the ad hoc network have pre-established
security associations, the purposes for which the security
associations are created should include that of authorizing the
processing of AODVv2 control packets. Given this understanding, the
mobile nodes should be able to use the same authentication mechanisms
based on their IP addresses as they would have used otherwise.
5.15. Acknowledgments
AODVv2 is a descendant of the design of previous MANET on-demand AODVv2 is a descendant of the design of previous MANET on-demand
protocols, especially AODV [RFC3561] and DSR [RFC4728]. Changes to protocols, especially AODV [RFC3561] and DSR [RFC4728]. Changes to
previous MANET on-demand protocols stem from research and previous MANET on-demand protocols stem from research and
implementation experiences. Thanks to Elizabeth Belding-Royer for implementation experiences. Thanks to Elizabeth Belding-Royer for
her long time authorship of AODVv2. Additional thanks to Luke Klein- her long time authorship of AODV. Additional thanks to Luke Klein-
Berndt, Pedro Ruiz, Fransisco Ros, Koojana Kuladinithi, Ramon Berndt, Pedro Ruiz, Fransisco Ros, Koojana Kuladinithi, Ramon
Caceres, Thomas Clausen, Christopher Dearlove, Seung Yi, Romain Caceres, Thomas Clausen, Christopher Dearlove, Seung Yi, Romain
Thouvenin, Tronje Krop, Henner Jakob, Alexandru Petrescu, Christoph Thouvenin, Tronje Krop, Henner Jakob, Alexandru Petrescu, Christoph
Sommer, Cong Yuan, Lars Kristensen, and Derek Atkins for reviewing of Sommer, Cong Yuan, Lars Kristensen, and Derek Atkins for reviewing of
AODVv2, as well as several specification suggestions. AODVv2, as well as several specification suggestions.
Many good ideas from LOADng [I-D.clausen-lln-loadng] are shaping this This revision of AODVv2 isolates the minimal base specification and
evolution of the [manet] reactive routing protocol specification. other optional features to simplify the process of ensuring
Thanks are due to T. Clausen, A. Colin de Verdiere, J. Yi, A. compatibility with the existing LOADng specification
Niktash, Y. Igarashi, SATOH. H., and U. Herberg for their [I-D.clausen-lln-loadng] (minimal reactive routing protocol
specification). Thanks are due to T. Clausen, A. Colin de Verdiere,
J. Yi, A. Niktash, Y. Igarashi, Satoh. H., and U. Herberg for their
development of LOADng and sharing details for ensuring development of LOADng and sharing details for ensuring
appropriateness of AODVv2 for LLNs. appropriateness of AODVv2 for LLNs.
10. References 6. References
10.1. Normative References
6.1. Normative References
[RFC1812] Baker, F., "Requirements for IP Version 4 Routers", [RFC1812] Baker, F., "Requirements for IP Version 4 Routers",
RFC 1812, June 1995. RFC 1812, June 1995.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C. [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C.
Pignataro, "The Generalized TTL Security Mechanism Pignataro, "The Generalized TTL Security Mechanism
(GTSM)", RFC 5082, October 2007. (GTSM)", RFC 5082, October 2007.
skipping to change at page 33, line 27 skipping to change at page 37, line 6
"Generalized Mobile Ad Hoc Network (MANET) Packet/Message "Generalized Mobile Ad Hoc Network (MANET) Packet/Message
Format", RFC 5444, February 2009. Format", RFC 5444, February 2009.
[RFC5497] Clausen, T. and C. Dearlove, "Representing Multi-Value [RFC5497] Clausen, T. and C. Dearlove, "Representing Multi-Value
Time in Mobile Ad Hoc Networks (MANETs)", RFC 5497, Time in Mobile Ad Hoc Networks (MANETs)", RFC 5497,
March 2009. March 2009.
[RFC5498] Chakeres, I., "IANA Allocations for Mobile Ad Hoc Network [RFC5498] Chakeres, I., "IANA Allocations for Mobile Ad Hoc Network
(MANET) Protocols", RFC 5498, March 2009. (MANET) Protocols", RFC 5498, March 2009.
10.2. Informative References 6.2. Informative References
[I-D.chakeres-manet-manetid]
Chakeres, I., "MANET_ID TLV",
draft-chakeres-manet-manetid-03 (work in progress),
February 2008.
[I-D.clausen-lln-loadng] [I-D.clausen-lln-loadng]
Clausen, T., Verdiere, A., Yi, J., Niktash, A., Igarashi, Clausen, T., Verdiere, A., Yi, J., Niktash, A., Igarashi,
Y., and U. Herberg, "The LLN On-demand Ad hoc Distance- Y., Satoh, H., Herberg, U., Lavenu, C., Lys, T., and C.
vector Routing Protocol - Next Generation (LOADng)", Perkins, "The LLN On-demand Ad hoc Distance-vector Routing
draft-clausen-lln-loadng-01 (work in progress), Protocol - Next Generation (LOADng)",
October 2011. draft-clausen-lln-loadng-05 (work in progress), July 2012.
[I-D.ietf-manet-nhdp]
Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc
Network (MANET) Neighborhood Discovery Protocol (NHDP)",
draft-ietf-manet-nhdp-15 (work in progress),
December 2010.
[I-D.ietf-ospf-multi-instance]
Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-
Instance Extensions", draft-ietf-ospf-multi-instance-09
(work in progress), January 2012.
[Perkins99] [Perkins99]
Perkins, C. and E. Belding-Royer, "Ad hoc On-Demand Perkins, C. and E. Belding-Royer, "Ad hoc On-Demand
Distance Vector (AODV) Routing", Proceedings of the 2nd Distance Vector (AODV) Routing", Proceedings of the 2nd
IEEE Workshop on Mobile Computing Systems and IEEE Workshop on Mobile Computing Systems and
Applications, New Orleans, LA, pp. 90-100, February 1999. Applications, New Orleans, LA, pp. 90-100, February 1999.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2501] Corson, M. and J. Macker, "Mobile Ad hoc Networking
(MANET): Routing Protocol Performance Issues and
Evaluation Considerations", RFC 2501, January 1999.
[RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On- [RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On-
Demand Distance Vector (AODV) Routing", RFC 3561, Demand Distance Vector (AODV) Routing", RFC 3561,
July 2003. July 2003.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
[RFC4728] Johnson, D., Hu, Y., and D. Maltz, "The Dynamic Source [RFC4728] Johnson, D., Hu, Y., and D. Maltz, "The Dynamic Source
Routing Protocol (DSR) for Mobile Ad Hoc Networks for Routing Protocol (DSR) for Mobile Ad Hoc Networks for
IPv4", RFC 4728, February 2007. IPv4", RFC 4728, February 2007.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007. September 2007.
[RFC5148] Clausen, T., Dearlove, C., and B. Adamson, "Jitter [RFC5148] Clausen, T., Dearlove, C., and B. Adamson, "Jitter
Considerations in Mobile Ad Hoc Networks (MANETs)", Considerations in Mobile Ad Hoc Networks (MANETs)",
RFC 5148, February 2008. RFC 5148, February 2008.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, July 2008. for IPv6", RFC 5340, July 2008.
[RFC6130] Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc
Network (MANET) Neighborhood Discovery Protocol (NHDP)",
RFC 6130, April 2011.
[RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-
Instance Extensions", RFC 6549, March 2012.
[RFC6621] Macker, J., "Simplified Multicast Forwarding", RFC 6621,
May 2012.
Appendix A. Changes since the Previous Version Appendix A. Changes since the Previous Version
o Protocol renamed to be AODVv2 o Internet-Facing AODVv2 router renamed to be IAR
o Intermediate RREPs (iRREPs) are to be put into new document. o "Optional Features" section created to contain features not
Without iRREP, only the destination can respond to a RREQ. required within base specification, including:
o Precursor lists not supported, based on reported performance loss. o
o Routing Messages MUST be originated with the MsgHdr.HopLimit set * Intermediate RREPs (iRREPs): Without iRREP, only the
to MSG_HOPLIMIT. Previously, this was not mandated. destination can respond to a RREQ.
o Adding additional unreachable destinations to RERR is not * Precursor lists.
specified in this document, to match LOADng behavior.
Appendix B. Proposed additional changes for LOADng conformance * An RERR may reporting multiple unreachable nodes.
o Revise message formats to be compatible with LOADng requirements,
removing RFC 5444 headers for minimal packet size
o Adding RREP-ACK message type instead of relying on reception of * Message Aggregation.
arbitrary packets as sufficient response to establish
bidirectionality.
Appendix C. Shifting Responsibility for an Address Between AODVv2 o Sequence number MUST (instead of SHOULD) be set to 1 after
rollover.
o ThisNode MUST (instead of SHOULD) only handle AODVv2 messages from
adjacent routers.
o Clarification that Additional Routing information in RteMsgs is
optional (MAY) to use.
o Clarification that if Additional Routing information in RteMsgs is
used, then the Route Table Entry SHOULD be updated using normal
procedures as described in Section 5.2.2.
o Clarification in Section 5.4 that nodes may be configured to
buffer zero packets.
o Clarification in Section 5.4 that buffered packets MUST be dropped
if route discovery fails.
o In Section 5.5.1, relax mandate for monitoring connectivity to
next-hop AODVv2 neighbors (from MUST to SHOULD), in order to allow
for minimal implementations
o Remove Route.Forwarding flag; identical to "NOT" Route.Broken.
o Routing Messages MUST be originated with the MsgHdr.HopLimit set
to MSG_HOPLIMIT. Previously, this was not mandated.
o Maximum hop count set to 254, with 255 reserved for "unknown".
Since the current draft only uses hop-count as distance, this is
also the current maximum distance.
Appendix B. Shifting Network Prefix Advertisement Between AODVv2
Routers Routers
Only one AODVv2 router within a routing region SHOULD be responsible Only one AODVv2 router within a routing region SHOULD be responsible
for a particular address at any time. If two AODVv2 routers for a particular address at any time. If two AODVv2 routers
dynamically pass responsibility of an address correct AODVv2 routing dynamically shift the advertisement of a network prefix, correct
behavior must be observed. The AODVv2 router adding the new address AODVv2 routing behavior must be observed. The AODVv2 router adding
must wait for any exiting routing information about this address to the new network prefix must wait for any existing routing information
be purged from the network. Therefore, it must wait at least about this network prefix to be purged from the network. Therefore,
ROUTER_SEQNUM_AGE_MAX_TIMEOUT after the previous AODVv2 router for it must wait at least ROUTER_SEQNUM_AGE_MAX_TIMEOUT after the
this address stopped participating and advertising routing previous AODVv2 router for this address stopped advertising routing
information on its behalf. information on its behalf.
Authors' Addresses Authors' Addresses
Charles E. Perkins Charles E. Perkins
Central Expressway Futurewei Inc.
San Jose, CA 95050 2330 Central Expressway
Santa Clara, CA 95050
USA USA
Phone: +1-408-421-1172 Phone: +1-408-330-5305
Email: charliep@computer.org Email: charliep@computer.org
Ian D Chakeres Ian D Chakeres
CenGen CenGen
9250 Bendix Road North 9250 Bendix Road North
Columbia, Maryland 21045 Columbia, Maryland 21045
USA USA
Email: ian.chakeres@gmail.com Email: ian.chakeres@gmail.com
URI: http://www.ianchak.com/ URI: http://www.ianchak.com/
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