Mobile Ad hoc Networks Working I. Chakeres Group Motorola Internet-Draft C. Perkins Intended status: Standards Track Nokia Expires:
January 6,May 21, 2008 July 5,November 18, 2007 Dynamic MANET On-demand (DYMO) Routing draft-ietf-manet-dymo-10draft-ietf-manet-dymo-11 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 6,May 21, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract The Dynamic MANET On-demand (DYMO) routing protocol is intended for use by mobile modes in wireless, multihop networks. It offers adaptation to changing network topology and determines unicast routes between DYMO routers within the network in an on-demand fashion. Table of Contents 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Applicability Statement . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Route Table Entry . . . . . . . . . . . . . . . . . . . . 7 4.2. DYMO Messages . . . . . . . . . . . . . . . . . . . . . . 8 4.2.1. Generalized MANET Packet and Message Structure . . . . 8 4.2.2. Routing Messages (RM) - RREQ & RREP . . . . . . . . . 9 4.2.3. Route Error (RERR) . . . . . . . . . . . . . . . . . . 1113 5. Detailed Operation . . . . . . . . . . . . . . . . . . . . . . 1314 5.1. DYMO Sequence Numbers . . . . . . . . . . . . . . . . . . 1314 5.1.1. Maintaining A Node's Own Sequence Number . . . . . . . 1315 5.1.2. Numerical Operations on OwnSeqNum . . . . . . . . . . 1415 5.1.3. OwnSeqNum Rollover . . . . . . . . . . . . . . . . . . 1415 5.1.4. Actions After OwnSeqNum Loss . . . . . . . . . . . . . 1415 5.2. DYMO Routing Table Operations . . . . . . . . . . . . . . 1415 5.2.1. Judging Routing Information's Usefulness . . . . . . . 1416 5.2.2. Creating or Updating a Route Table Entry with New Routing Information . . . . . . . . . . . . . . . . . 1617 5.2.3. Route Table Entry Timeouts . . . . . . . . . . . . . . 1618 5.3. Routing Messages . . . . . . . . . . . . . . . . . . . . . 1819 5.3.1. RREQ Creation . . . . . . . . . . . . . . . . . . . . 1819 5.3.2. RREP Creation . . . . . . . . . . . . . . . . . . . . 1920 5.3.3. Intermediate DYMO Router RREP Creation . . . . . . . . 1921 5.3.4. RM Processing . . . . . . . . . . . . . . . . . . . . 2021 5.3.5. Adding Additional Routing Information to a RM . . . . 2224 5.4. Route Discovery . . . . . . . . . . . . . . . . . . . . . 2324 5.5. Route Maintenance . . . . . . . . . . . . . . . . . . . . 2325 5.5.1. Active Link Monitoring . . . . . . . . . . . . . . . . 2426 5.5.2. Updating Route Lifetimes During Packet Forwarding . . 2426 5.5.3. Route Error Generation . . . . . . . . . . . . . . . . 2426 5.5.4. RERR Processing . . . . . . . . . . . . . . . . . . . 2527 5.6. Unknown Message & TLV Types . . . . . . . . . . . . . . . 2628 5.7. Advertising Network Addresses . . . . . . . . . . . . . . 2628 5.8. Simple Internet Attachment and Gatewaying . . . . . . . . 2628 5.9. Multiple Interfaces . . . . . . . . . . . . . . . . . . . 2830 5.10. Packet/Message Generation Limits . . . . . . . . . . . . . 2830 6. Configuration Parameters and Other Administrative Options . . 2830 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 2931 7.1. DYMO Message Type Specification . . . . . . . . . . . . . 3032 7.2. Packet and Message TLV Type Specification . . . . . . . . 3032 7.3. Address Block TLV Specification . . . . . . . . . . . . . 3133 8. Security Considerations . . . . . . . . . . . . . . . . . . . 3133 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 3134 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 3234 10.1. Normative References . . . . . . . . . . . . . . . . . . . 3234 10.2. Informative References . . . . . . . . . . . . . . . . . . 3234 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 3335 Intellectual Property and Copyright Statements . . . . . . . . . . 3436 1. Overview The Dynamic MANET On-demand (DYMO) routing protocol enables reactive, multihop unicast routing between participating DYMO routers. The basic operations of the DYMO protocol are route discovery and route management. During route discovery, the originator's DYMO router initiates dissemination of a Route Request (RREQ) throughout the network to find a route to the target's DYMO router. During this hop-by-hop dissemination process, each intermediate DYMO router records a route to the originator. When the target's DYMO router receives the RREQ, it responds with a Route Reply (RREP) sent hop-by- hop toward the originator. Each intermediate DYMO router that receives the RREP records a route to the target, and then the RREP is unicast hop-by-hop toward the originator. When the originator's DYMO router receives the RREP, routes have then been established between the originating DYMO router and the target DYMO router in both directions. In order to preserve routes in use, DYMO routers extend route lifetimes upon successfully forwarding a packet. In order to react to react tochanges in the network topology, DYMO routers monitor links over which traffic is moving. When a data packet is received for forwarding if a route for the destination is not known or the route is broken, then the DYMO router of source of the packet is notified. A Route Error (RERR) is sent toward the packet source to indicate the current route to a particular destination is broken. When the source's DYMO router receives the RERR, it deletes the route. If the DYMO router later receives a packet for forwarding to the same destination, it must perform route discovery again. DYMO uses sequence numbers to ensure loop freedom [Perkins99]. Sequence numbers enable DYMO routers to determine the order of DYMO route discovery messages, thereby avoiding use of stale routing information. 2. Applicability Statement The DYMO routing protocol is designed for stub or disconnected mobile ad hoc networks. DYMO handles a wide variety of mobility patterns by dynamically determining routes on-demand. DYMO also handles a wide variety of traffic patterns. In large networks DYMO is best suited for traffic scenarios where nodes communicate with only a portion of otherthe other nodes. DYMO is applicable to memory constrained devices, since little routing state must be maintained in each DYMO router. Only routing information related to active sources and destinations must be maintained, in contrast to other routing protocols that require routing information to all routers within the routing region be maintained. DYMO supports routers which have multiple interfaces participating in the MANET. DYMO also supports nodes which have non-MANET interfaces to which hosts can attach. DYMO routers perform route discovery to find a route to a particular destination. Therefore, DYMO routers must be configured to initiate route discovery for certain destinations. When DYMO is the only protocol interacting with the forwarding table, DYMO should be configured to perform route discovery for all unknown unicast destinations. DYMO should only utilizes bidirectional links. In the case of possible unidirectional links, either blacklists (see Section 7.2) or other means (e.g. only accepting RM from bidirectional links as indicated by NHDP [I-D.ietf-manet-nhdp]) of ensuring bi- directionality should be used. Otherwise, persistent packet loss may occur. The routing algorithm in DYMO may be operated at layers other than the network layer, using layer-appropriate addresses. Only modification of the packet format is required. The routing algorithm need not change. Note that, using the DYMO algorithm with message formats other than those specified in this document will not be interoperable. 3. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Additionally, this document uses some terminology from [I-D.ietf-manet-packetbb]. This document defines the following terminology: Distance (Dist) A metric of the distance a message or piece of information has traversed. The minimum value of distance is the number of IP hops traversed. The maximum value is 65,535. DYMO Sequence Number (SeqNum) A DYMO Sequence Number is maintained by each DYMO router. This sequence number is used by other DYMO routers to identify the order of routing information generated and ensure loop-free routes. Forwarding Route A route that is used to forward data packets. Forwarding routes are generally maintained in a forwarding information base (FIB) or the kernel forwarding/routing table. Originating Node (OrigNode) The originating node is the DYMO router that creates a DYMO Message in an effort to disseminate some information. The originating node is also referred to as a particular message's originator. Route Error (RERR) A RERR message is used indicate that a DYMO router does not have forwarding route to one or more particular addresses. Route Reply (RREP) A RREP message is used to disseminate routing information about the RREP OrigNode to the RREP TargetNode and the DYMO routers between them. Route Request (RREQ) A RREQ message is issued to discover a valid route to a particular destination address, called the RREQ TargetNode. When a DYMO router processes a RREQ, it learns routing 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 DYMO router currently performing a calculation or processing a message. Type-Length-Value structure (TLV) A generic way to represent information, please see [I-D.ietf-manet-packetbb] for additional information. Unreachable Node (UnreachableNode) An UnreachableNode is a node for which a forwarding route does not exist. 4. Data Structures 4.1. Route Table Entry The route table entry is a conceptual data structure. Implementations may use any internal representation that conforms to the semantics of a route as specified in this document. Conceptually, a route table entry has the following fields: Route.Address The IP (host or network) destination address of the node(s) associated with the routing table entry. Route.SeqNum The DYMO SeqNum associated with this routing information. Route.NextHopAddress The IP address of the next DYMO router on the path toward the Route.Address. Route.NextHopInterface The interface used to send packets toward the Route.Address. Route.Broken A flag indicating whether this Route is broken. This flag is set if the next hop becomes unreachable or in response to processing a RERR (see Section 5.5.4). The following fields are optional: Route.Dist A metric indicating the distance traversed before reaching the Route.Address node. Route.Prefix Indicates that the associated address is a network address, rather than a host address. The value is the length of the netmask/ prefix. If an address block does not have an associated PREFIX_LENGTH TLV [I-D.ietf-manet-packetbb], the prefix may be considered to have a prefix length equal to the address length (in bits).in bits. Not including optional information may cause performance degradation, but it will not cause the protocol to operate incorrectly. In addition to a route table data structure, each route table entry may have several timers associated with the information. These timers/timeouts are discussed in Section 5.2.3. 4.2. DYMO Messages When describing DYMO protocol messages, it is necessary to refer to fields in several distinct parts of the overall packet. These locations include the IP or IPv6 header, the UDP header, and fields from [I-D.ietf-manet-packetbb]. This document uses the following notation conventions. Information found in the table. +----------------------------+-------------------+ | Information Location | Notational Prefix | +----------------------------+-------------------+ | IP header | IP. | | UDP header | UDP. | | packetbb message header | MsgHdr. | | packetbb message TLV | MsgTLV. | | packetbb address blocks | AddBlk. | | packetbb address block TLV | AddTLV. | +----------------------------+-------------------+ Table 1 4.2.1. Generalized MANET Packet and Message Structure DYMO messages conform to the generalized packet and message format as described in [I-D.ietf-manet-packetbb]. 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. All DYMO messages specified in this document are sent using UDP to the destination port MANET [I-D.ietf-manet-iana]. Most DYMO messages are sent with the IP destination address set to the link-local multicast address LL MANET ROUTERS unless otherwise stated. Therefore, all DYMO routers SHOULD subscribe to LL MANET ROUTERS for receiving control packets. Unicast DYMO messages 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 DYMO messages is set to one (1) for all messages specified in this document. The length of an IP address (32 bits for IPv4 and 128 bits for IPv6) inside a DYMO message depends on the IP packet header containing the DYMO message/packet. For example, if the IP header uses IPv6 addresses then all messages and addresses contained in the payload use IPv6 addresses. In the case of mixed IPv6 and IPv4 addresses, please see [I-D.ietf-manet-packetbb]. If a packet contains only a single DYMO message and no packet TLVs, it need not include a packet-header [I-D.ietf-manet-packetbb]. The aggregation of multiple messages into a packet is not specified in this document, but 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 introducing jitter [I-D.ietf-manet-jitter]. 4.2.2. Routing Messages (RM) - RREQ & RREP Routing Messages (RMs) are used to disseminate routing information. There are two DYMO message types that are considered to be routing messages (RMs): RREQ and RREP. They contain very similar information and function, but have slightly different processing rules. The main difference between the two messages is that RREQ messages generally solicit a RREP, whereas a RREP is the response to RREQ. RM creation and processing are described in Section 5.3. A RM requires the following information: IP.SourceAddress The IP address of the node currently sending this packet. This field is generally filled automatically by the operating system and should not require special handling. IP.DestinationAddress The IP address of the packet destination. For RREQ the IP.DestinationAddress is set to LL MANET ROUTERS. For RREP the IP.DestinationAddress is set to the NextHopAddress toward the RREP TargetNode. UDP.DestinationPort The UDP destination port is set to MANET [I-D.ietf-manet-iana]. MsgHdr.HopLimit The remaining number of hops this message is allowed to traverse. AddBlk.TargetNode.Address The IP address of the message TargetNode. In a RREQ the TargetNode is the destination for which a forwarding route does not exist and route discovery is being performed. In a RREP the TargetNode is the RREQ OrigNode DYMO router. The TargetNode address is the first address in a routing message. AddBlk.OrigNode.Address The IP address of the originator. In a RREQ the OrigNode is the source's DYMO router for which a route discovery is being performed. In a RREP the OrigNode is the RREQ TargetNode's DYMO router for which a RREP is being generated. This address is the second address in the message for RREQ. OrigNode.AddTLV.SeqNum The DYMO sequence number of the originator's DYMO router. A RM may optionally include the following information: TargetNode.AddTLV.SeqNum The last known DYMO sequence number of the TargetNode. TargetNode.AddTLV.Dist The last known distance to the TargetNode. AddBlk.AdditionalNode.Address The IP address of an additional node that can be reached via the DYMO router adding this information. Each AdditionalNode.Address must have an associated Node.SeqNum in the address TLV block. AdditionalNode.AddTLV.SeqNum The DYMO sequence number associated with this routing information. Node.AddTLV.DistOrigNode.AddTLV.Dist A metric of the distance to reach the associated Node.Address.OrigNode.Address. This field is incremented by at least one at each intermediate DYMO router, exceptrouter. AdditionalNode.AddTLV.Dist A metric of the TargetNode.AddTLV.Dist. The TargetNode'sdistance informationto reach the associated AdditionalNode.Address. This field is not modified. Node.AddTLV.Prefixincremented by at least one at each intermediate DYMO router. OrigNode.AddTLV.Prefix The OrigNode.Address is a network address with a particular prefix length. AdditionalNode.AddTLV.Prefix The Node.AddressAdditionalNode.Address is a network address with a particular prefix length. Example IPv4 RREQ 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 IP Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP.SourceAddress | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP.DestinationAddress = LL MANET ROUTERS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... UDP Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Port = MANET | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Message Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RREQ-type | Rsv |N|1|1|0|1| msg-size=23 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-hoplimit | +-+-+-+-+-+-+-+-+ ... Message Body - Message TLV Block +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-tlv-block-size=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Message Body - Address Block +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Number Addrs=2 | Resv |0|1|0| HeadLength=3 | Head : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Head (cont) | Target.Tail | Orig.Tail | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Message Body - Address Block TLV Block +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | tlv-block-size=6 |DYMOSeqNum-type|Rsv|0|1|0|0|0|0| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Index-start=1 | tlv-length=2 | Orig.SeqNum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 4.2.3. Route Error (RERR) A RERR message is used to disseminate the information that a route is not available for one or more particular IP addresses. RERR creation and processing are described in Section 5.5. A RERR requires the following information: IP.SourceAddress The IP address of the node currently sending this packet. This field is generally filled automatically by the operating system and should not require special handling. IP.DestinationAddress The IP address is set to LL MANET ROUTERS. UDP.DestinationPort The UDP destination port is set to MANET [I-D.ietf-manet-iana]. MsgHdr.HopLimit The remaining number of hops this message is allowed to traverse. AddBlk.UnreachableNode.Address The IP address of an UnreachableNode. Multiple unreachable addresses may be included in a RERR. A Route Error may optionally include the following information: UnreachableNode.AddTLV.SeqNum The last known DYMO sequence number of the unreachable node. If a SeqNum for an address is not included, it is assumed to be unknown. This case occurs when a node receives a message to forward to a destination for which it does not have any information in its routing table. Example IPv4 RERR 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 IP Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP.SourceAddress | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP.DestinationAddress = LL MANET ROUTERS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... UDP Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Port = MANET | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Message Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RERR-type |Resv |0|1|1|0|1| msg-size=15 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-hoplimit | +-+-+-+-+-+-+-+-+ ... Message Body +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-tlv-block-size=0 |Number Addrs=1 | Resv |0|1|1| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Unreachable.Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV-blk-size=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 5. Detailed Operation 5.1. DYMO Sequence Numbers DYMO sequence numbers allow nodes to judge the freshness of routing information and ensure loop freedom. 5.1.1. Maintaining A Node's Own Sequence Number DYMO requires that each DYMO router in the network to maintain its own DYMO sequence number (OwnSeqNum), a 16-bit unsigned integer. The circumstances for ThisNode to incrementing its OwnSeqNum are described in Section 5.3. 5.1.2. Numerical Operations on OwnSeqNum When ThisNode increments its OwnSeqNum (as described in Section 5.3) it MUST do so by treating the sequence number value as an unsigned number. Note: The sequence number zero (0) is reserved. 5.1.3. OwnSeqNum Rollover If the sequence number has been assigned to be the largest possible number representable as a 16-bit unsigned integer (i.e., 65535),65,535), then the sequence number is set to 256 when incremented. Setting the sequence number to 256 allows other nodes to detect that the number has rolled over and the node has not lost its sequence number. 5.1.4. Actions After OwnSeqNum Loss A node should maintain its sequence number in persistent storage, between reboots. If a node's OwnSeqNum is lost, it must take certain actions to avoid creating routing loops. To prevent this possibility after OwnSeqNum loss a node MUST wait for at least ROUTE_DELETE_TIMEOUT before fully participating in the DYMO routing protocol. If a DYMO control message is received during this waiting period, the node SHOULD process it normally but MUST notNOT transmit or retransmit any DYMO messages. If a data packet is received for forwarding to another destination during this waiting period, the node MUST generate a RERR message indicating that this route is not available and reset its waiting timeout. At the end of the waiting period a node sets its OwnSeqNum to one (1). The longest a node must wait is ROUTE_AGE_MAX_TIMEOUT. At the end of the maximum waiting period a node sets its OwnSeqNum to one (1) and begins participating. 5.2. DYMO Routing Table Operations 5.2.1. Judging Routing Information's Usefulness Given a route table entry (Route.SeqNum, Route.Dist, and Route.Broken) and new incoming routing information for a particular node in a RM (Node.SeqNum, Node.Dist, and RM message type - RREQ/ RREP), the quality of the new routing information is evaluated to determine its usefulness. Incoming routing information is 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) 2. Loop-possible If Node.SeqNum == Route.SeqNum the incoming information may cause loops if used; in this case additional information must be examined. If Route.Dist or Node.Dist is unknown or zero (0), then the routing information is loop-possible. If Node.Dist > Route.Dist + 1, then the routing information is loop-possible. Using loop-possible routing information is not allowed, otherwise routing loops may be formed. (Node.SeqNum == Route.SeqNum) AND ((Node.Dist is unknown) OR (Route.Dist is unknown) OR (Node.Dist > Route.Dist + 1)) 3. Inferior In case of known equal SeqNum, the information is inferior,inferior in multiple cases: (case i) if Node.Dist >== Route.Dist + 1 (it is a greater distance route). In case of equal SeqNum, the information is inferior,route) AND Route.Broken == false; (case ii) if Node.Dist == Route.Dist (equal distance route) AND Route.Broken == false AND this RM is a RREQ. ThisThe inferior condition stops forwarding of RREQ with equivalent distance. ((Node.SeqNum == Route.SeqNum) AND ((Node.Dist > Route.Dist)(((Node.Dist == Route.Dist + 1) AND (Route.Broken == false)) OR ((Node.Dist == Route.Dist) AND (RM is RREQ) AND (Route.Broken == false)))) 4. Superior Incoming routing information that does not match any of the above criteria is loop-free and better than the information existing in the routing table. Information is always superior if Node.SeqNum - Route.SeqNum > 0 (using 16-bit signed arithmetic). In the case of equal sequence numbers, the information is superior,superior in multiple cases: (case i) if Node.Dist < Route.Dist. In the case of equal sequence numbers, the informationRoute.Dist; (case ii) if Node.Dist == Route.Dist + 1 AND Route.Broken == true (a broken route is superior,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 ((Node.SeqNum == Route.SeqNum) AND ((Node.Dist < Route.Dist) OR ((Node.Dist == Route.Dist + 1) AND (Route.Broken == true)) OR ((Node.Dist == Route.Dist) AND ((RM is RREP) OR (Route.Broken == true))))) 5.2.2. Creating or Updating a Route Table Entry with New Routing Information The route table entry is populated with the following information: 1. the Route.Address is set to Node.Address, 2. the Route.SeqNum is set to the Node.SeqNum, 3. the Route.NextHopAddress is set to the node that transmitted this DYMO RM packet (i.e., the IP.SourceAddress), 4. the Route.NextHopInterface is set to the interface that this DYMO packet was received on, 5. if known, the Route.Dist is set to the Node.Dist, 6. if known, the Route.Prefix is set to the Node.Prefix. Fields without known values are not populated with any value. Previous timers for this route table entry are removed. A timer for the minimum delete timeout (ROUTE_AGE_MIN) is set to ROUTE_AGE_MIN_TIMEOUT. A timer to indicate a recently learned route (ROUTE_NEW) is set to ROUTE_NEW_TIMEOUT. A timer for the maximum delete timeout (ROUTE_AGE_MAX). ROUTE_AGE_MAX is set to Node.AddTLV.MaxAge if included; otherwise, ROUTE_AGE_MAX is set to ROUTE_AGE_MAX_TIMEOUT. The usage of these timers and others are described in Section 5.2.3. At this point, a forwarding route should be installed. Afterward, the route can be used to send any queued data packets and forward any incoming data packets for Route.Address. This route also fulfills any outstanding route discovery attempts for Node.Address. 5.2.3. Route Table Entry Timeouts 126.96.36.199. Minimum Delete Timeout (ROUTE_AGE_MIN) When a DYMO router transmits a RM, other DYMO routers expect the transmitting DYMO router to have a forwarding route to the RM originator. After updating a route table entry, it should be maintained for at least ROUTE_AGE_MIN. Failure to maintain the information might result in lost messages/packets, or in the worst case scenario several duplicate messages. After the ROUTE_AGE_MIN timeout a route can safely be deleted. 188.8.131.52. Maximum Delete Timeout (ROUTE_AGE_MAX) Sequence number information is time sensitive, and must be deleted after a time in order to avoid conflicts due to reboots and rollovers. When a DYMO router has lost its sequence number (e.g, due to daemon reboot or node replacement) the DYMO router must wait until routing information associated with that IP address and sequence number are no longer maintained by other DYMO routers in the network to ensure loop-free routing. After the ROUTE_AGE_MAX timeout a route must be deleted. All information about the route is deleted upon ROUTE_AGE_MAX timeout. If a forwarding route exists it is also removed. 184.108.40.206. New Information Timeout (ROUTE_NEW) As time progresses the likelihood that a route remains intact decreases, if the network nodes are mobile. Maintaining and using old routing information can lead to many DYMO messages and excess route discovery delay. After the ROUTE_NEW timeout if the route has not been used, a timer for deleting the route (ROUTE_DELETE) is set to ROUTE_DELETE_TIMEOUT. 220.127.116.11. Recently Used Timeout (ROUTE_USED) 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 Section 5.5.2. If a route has not been used recently, then a timer for ROUTE_DELETE is set to ROUTE_DELETE_TIMEOUT. 18.104.22.168. Delete Information Timeout (ROUTE_DELETE) As time progresses the likelihood that old routing information is useful decreases, especially if the network nodes are mobile. Therefore, old information should be deleted. After the ROUTE_DELETE timeout, the routing table entry should be deleted. If a forwarding route exists, it should also be removed. 5.3. Routing Messages 5.3.1. RREQ Creation When a DYMO router creates a RREQ it SHOULD increment its OwnSeqNum by one (1) according to the rules specified in Section 5.1.2. Incrementing OwnSeqNum will ensure that all nodes with existing routing information to consider this new information fresh. If the sequence number is not incremented, certain DYMO routers might not consider this information useful if they have superior information already. First, ThisNode adds the AddBlk.TargetNode.Address to the RREQ; the IP.DestinationAddress for which a forwarding route does not exist. If a previous value of the TargetNode.SeqNum is known (from a routing table entry using longest-prefix matching), it SHOULD be placed in TargetNode.AddTLV.SeqNum in all but the last RREQ attempt. If a TargetNode.SeqNum is not included, it is assumed to be unknown by processing nodes. This operation ensures that no intermediate DYMO routers reply, and ensures that the TargetNode's DYMO router increments its sequence number. Similarly, if a previous value of the TargetNode.Dist is known, it SHOULD be placed in TargetNode.AddTLV.Dist. Otherwise, the TargetNode.AddTLV.Dist is not included and assumed unknown by processing nodes. Next, the node adds AddBlk.OrigNode.Address to the RM and the OrigNode.AddTLV.SeqNum (OwnSeqNum) in an address block TLV. The OrigNode.Address is the address of the DYMO router that is initiating this route discovery. The OrigNode.Address must be a routable IP address. If this DYMO router is performing route discovery on behalf of an attached node (the(i.e. the source of the data packet forcingcausing this route discovery), itthe DYMO router MUST advertise it's address and prefix that contain the sourcesource's address. This information will be used by nodes to create a route toward the OrigNode, enable delivery of a RREP, and eventually for data packets. If OrigNode.Dist is included it is set to a number greater than zero (0). The MsgHdr.HopLimit should be set to MAX_HOPLIMIT, but may be set smaller. 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 network and possibly reduce route discovery overhead. The IP.DestinationAddress for RREQ is set to LL MANET ROUTERS. 5.3.2. RREP Creation When the TargetNode's DYMO router creates a RREP, if the TargetNode.SeqNum was not included in the RREQ it MUST increment its OwnSeqNum by one (1) according to the rules specified in Section 5.1.2. If TargetNode.SeqNum is included in the RM and TargetNode.SeqNum from the RM is less than OwnSeqNum,- OwnSeqNum < 0 (using signed 16-bit arithmetic), OwnSeqNum SHOULD be incremented by one (1) according to the rules specified in Section 5.1.2. If TargetNode.SeqNum is included in the RM and TargetNode.SeqNum == OwnSeqNum (using signed 16-bit arithmetic) and Dist will not be included in the RREP being generated, OwnSeqNum SHOULD be incremented by one (1) according to the rules specified in Section 5.1.2. If OwnSeqNum is not incremented the routing information might be considered stale. In this case, the RREP would not reach the RREP Target. First, the AddBlk.TargetNode.Address is added to the RREP. The TargetNode is the ultimate destination of this RREP; the RREQ OrigNode.Address. Next, AddBlk.OrigNode.Address is added to the RREP. The AddBlk.OrigNode.Address must be a routable IP address. If the RREQ TargetNode is this DYMO router, its address added to the RREP as the OrigNode.Address. If the RREQ TargetNode is attached to this DYMO router, it MUST advertise its address and prefix that contain the RREQ TargetNode.Address. The RREP OrigNode.AddTLV.SeqNum (OwnSeqNum) must also added to the RREP. Other AddTLVs in the RREP for the OrigNode and TargetNode SHOULD be included and set accordingly. If OrigNode.Dist is included it is set to a number greater than zero (0). The MsgHdr.HopLimit is set to MAX_HOPLIMIT. The IP.DestinationAddress for RREP is set to the IP address of the Route.NextHopAddress for the route to the RREP TargetNode. 5.3.3. Intermediate DYMO Router RREP Creation Sometimes a DYMO router other than the TargetNode's DYMO router (call it an "intermediate DYMO router") has routing information that can satisfy an incoming RREQ. An intermediate DYMO router can issue a intermediate DYMO router RREP on behalf of the TargetNode's DYMO router. Before creating a intermediate DYMO router RREP, OwnSeqNum SHOULD be incremented by one (1) according to the rules specified in Section 5.1.2. If OwnSeqNum is not incremented the routing information might be considered stale by a processing DYMO router. In this case, the RREP would not reach the RREP Target. When an intermediate DYMO router originates a RREP in response to a RREQ on behalf of the TargetNode,TargetNode's DYMO router, it sends the RREP to the RREQ OrigNode with additional routing information (Address, SeqNum, Prefix, Dist, etc.) about the RREQ TargetNode. Appending additional routing information is described in Section 5.3.5. The Intermediate DYMO router SHOULD also issue a RREP to the RREQ TargetNode, so that the RREQ TargetNode receives routing information on how to reach the RREQ OrigNode. When an intermediate DYMO router creates this RREP, it sends a RREP to the RREQ TargetNode with additional routing information (Address, SeqNum, Dist, Prefix, etc.) about the RREQ OrigNode. 5.3.4. RM Processing Before processing a RM, the DYMO router checks the IP.Destination to ensure that it was sent to LL MANET ROUTERS. When a RM is received the MsgHdr.HopLimit is decremented by one (1)(1). For each address (except the TargetNode) in the RM that includes AddTLV.Dist information, the AddTLV.Dist information is incremented by at lease one (1). Next, ThisNode checks whether AddBlk.OrigNode.Address is an address handled by this DYMO router. If this node is the originating DYMO router, the RM is dropped. Next, ThisNode checks whether its routing table has an entry to the AddBlk.OrigNode.Address using longest-prefix matching [RFC1812]. If a route does not exist and the address is a unicast address, then the new routing information is considered fresh and a new route table entry is created and updated as described in Section 5.2.2. If a route table entry does exists, 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 superior, the route table entry is updated as described in Section 5.2.2. After processing the OrigNode's routing information, then each address that is not the TargetNode should 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) in the near future. For each of the additional addresses considered, if the address is a unicast address and the routing table does not have a matching route using longest-prefix matching, then a route is created and updated as described in Section 5.2.2. If a route table entry exists, 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 superior, the route table entry is updated as described in Section 5.2.2. If the routing information for an AdditionalNode.Address is not a unicast address and considered superior, then it is removed from the RM. Removing this information ensures that the information is not propagated. At this point, if the routing information for the OrigNode was not superior then this RM should be discarded and no further processing of this message is performed. If the ThisNode is the DYMO router for the TargetNode and this RM is a RREQ, then ThisNode responds with a RREQ flood (a RREQ addressed to oneself) or aRREP to the RREQ OrigNode (the new RREP's TargetNode). Alternatively, to distribute routing information about ThisNode (the RREQ TargetNode) more widely, ThisNode may optionally perform a RREQ; by issuing a RREQ with ThisNode listed as the TargetNode, using the procedure in Section 5.3.1. The procedure for issuing a new RREP is described in Section 5.3.2. Note: it is important that when creating the RREP, the RREP OrigNode.Address be the same as the RREQ TargetNode.Address, if ThisNode is responsible for several addresses. At this point, ThisNode need not perform any more operations for this RM. If ThisNode is not the TargetNode, this RM is a RREQ, the RREQ contains the TargetNode.AddTLV.SeqNum, and ThisNode has a forwarding route to the TargetNode with a SeqNum (Route.TargetNode.SeqNum) greater than or equal to the RREQ TargetNode.AddTLV.SeqNum;where Route.TargetNode.SeqNum - RREQ.TargetNode.AddTLV.SeqNum >= 0 (using signed 16-bit arithmetic); then this node MAY respond with an intermediate DYMO router RREP. The procedure for performing intermediate DYMO router RREP is described in Section 5.3.3. At this point, ThisNode need not perform any more operations for this RM. After processing a RM or creating a new RM, a node can append additional routing information to the RM, according to the procedure described in Section 5.3.5. The additional routing information can help reduce route discoveries at the expense of increased message size. For each address (except the TargetNode) in the RM that includes AddTLV.Dist information, the AddTLV.Dist information is incremented by a cost value. Advice regarding the cost value is not included in this specification, it is left up to the implementation. The updated distance value will be an measure in determining whether the routing information is inferior or superior to known information at other DYMO routers that process this RM. If the resulting distance value for the OrigNode is greater than 254,65,535, the message is discarded. If the resulting distance value for another node is greater than 254,65,535, the associated address and its information are removed from the RM. If this RM's MsgHdr.HopLimit is greater than or equal to one (1), ThisNode is not the TargetNode, AND this RM is a RREQ, then the current RM (altered by the procedure defined above) SHOULD be sent to the LL MANET ROUTERS IP.DestinationAddress. By sending the RM ThisNode is advertising that it will provide routing for IP addresses contained in the outgoing RM based on the information enclosed. ThisNode MAY choose not to send the RM, though not resending this RM could decrease connectivity in the network or result in a non-shortest distance path. Some examples of why ThisNode might choose to not send the RM are: if ThisNode does not want to advertise routing for the contained IP addresses because it is already congested; if ThisNode has already issued nearly identical routing information (e.g. ThisNode had recently issued a RM with nearly the same distance); or if ThisNode is low on energy and does not want to expend energy for control message sending or packet forwarding. This type of advanced behavior is not defined in this specification. If this RM's MsgHdr.HopLimit is greater than or equal to one (1), ThisNode is not the TargetNode, AND this RM is a RREP, then the current RM is sent to the Route.NextHopAddress for the RREP's TargetNode.Address. If no forwarding route exists to Target.Address, then a RERR is issued to the OrigNode of the RREP. 5.3.5. Adding Additional Routing Information to a RM Appending routing information can alleviate route discovery attempts to the nodes whose information is included, if other DYMO routers use this information to update their routing tables. DYMO routers can append routing information to a RM. This option should be administratively configurable. Prior to appending an address controlled by this DYMO router to a RM, ThisNode MAY increment its OwnSeqNum as defined in Section 5.1.2. If OwnSeqNum is not incremented the appended routing information might not be considered fresh, when received by nodes with existing routing information. Incrementation of the sequence number when appending information to an RM in transit should be administratively configurable. If an address controlled by this DYMO router is includedincludes ThisNode.Dist, it is set to a number greater than zero (0). For added addresses not controlled by this DYMO router, Route.Dist can be included if known. If Route.Dist is not known, it cannot be included. Additional information about the appended address(es) can also be appended, such as a PREFIX_LENGTH AddTLV.included (e.g. Prefix). 5.4. Route Discovery When a source's DYMO router needs to forward a data packet and it does not have a forwarding route to the IP.DestinationAddress, it sends a RREQ (described in Section 5.3.1) to discover a route to the particular destination (TargetNode). After issuing a RREQ, the OrigNode DYMO router waits for a route to be created to the TargetNode. If a route is not created within RREQ_WAIT_TIME, ThisNode may again try to discover a route by issuing another RREQ.RREQ using the procedure defined in Section 5.3.1. To reduce congestion in a network, repeated attempts at route discovery for a particular TargetNode should utilize an exponential backoff. For example, the first time a DYMO 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 DYMO router MAY send another RREQ. If a route is not found within two (2) times the current waiting time, another RREQ may be sent, up to a total of RREQ_TRIES. 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 DYMO router. This buffer should have a fixed limited size (BUFFER_SIZE_PACKETS or BUFFER_SIZE_BYTES) and older data packets SHOULD be discarded first. Buffering of data packets may have positive or negative impact, and therefore must be administratively configurable. If a route discovery has been attempted RREQ_TRIES times without receiving a route to the TargetNode, all data packets destined for the corresponding TargetNode are dropped from the buffer and a Destination Unreachable ICMP message should be delivered to the source. 5.5. Route Maintenance A RERR MUST be issued if a data packet is to be forwarded and it cannot be delivered to the next hop because no forwarding route for the IP.Destination exists; RERR generation is described in Section 5.5.3. Upon this condition, an ICMP Destination Unreachable message SHOULD NOT be generated unless this router is responsible for the IP.Destination and that IP.Destination is known to be unreachable. In addition to inability to forward a data packet, a RERR SHOULD be issued immediately after detecting a broken link of an forwarding route to quickly notify DYMO routers that a link break occurred and that certain routes are no longer available. If the route with the broken link has not been used recently (indicated by ROUTE_USED), the RERR SHOULD NOT be generated. 5.5.1. Active Link Monitoring Nodes MUST monitor next hop links on forwarding routes. This monitoring can be accomplished by one or several mechanisms, including: o Link layer feedback o Neighborhood discovery [I-D.ietf-manet-nhdp] o Route timeout o Other monitoring mechanisms or heuristics Upon detecting a link break (or an unreachable next hop) ThisNode must remove the affected forwarding routes (those with an unreachable next hop). ThisNode also flags these routes as Broken. For each broken route a timer for ROUTE_DELETE is set to ROUTE_DELETE_TIMEOUT. 5.5.2. Updating Route Lifetimes During Packet Forwarding To avoid removing the forwarding route to reach the IP.SourceAddress, a node SHOULD set a timeout (ROUTE_USED) to ROUTE_USED_TIMEOUT for the route to the IP.SourceAddress upon receiving a data packet. If a timer for ROUTE_DELETE is set, it is removed. To avoid removing the forwarding route to the IP.DestinationAddress that is being used, a node SHOULD set a timeout (ROUTE_USED) to ROUTE_USED_TIMEOUT for the route to the IP.DestinationAddress upon sending a data packet. If a timer for ROUTE_DELETE is set, it is removed. 5.5.3. Route Error Generation A RERR informs DYMO routers that a route to certain destinations is not available through this node. When creating a new RERR, the address of first UnreachableNode (IP.DestinationAddress from a data packet or RREP.TargetNode.Address) is inserted into an Address Block AddBlk.UnreachableNode.Address. If a value for the UnreachableNode's SeqNum (UnreachableNode.AddTLV.SeqNum) is known, it SHOULD be placed in the RERR. The MsgHdr.HopLimit is set to MAX_HOPLIMIT. Additional UnreachableNodes that require the same unavailable link (routes with the same Route.NextHopAddress and Route.NextHopInterface) SHOULD be added to the RERR, as additional AddBlk.UnreachableNode.Address. The SeqNum if known SHOULD also be included. Appending UnreachableNode information notifies each processing node of additional routes that are no longer available. This option SHOULD be administratively configurable. If SeqNum information is not known or not included in the RERR, all nodes processing the RERR will assume their routing information associated with the UnreachableNode is no longer valid and flags those routes as broken. The RERR is sent to the IP.DestinationAddress LL MANET ROUTERS. Sending the RERR to the LL MANET ROUTERS address notifies nearby nodes that might depend on the now broken link. The packet or message that forced generation of this RERR is discarded. 5.5.4. RERR Processing Before processing a RERR, the DYMO router checks the IP.Destination to ensure that it is addressed to LL MANET ROUTERS. Upon reception of a RERR the MsgHdr.HopLimit is decremented by one (1). When a DYMO router processes a RERR, it processes each UnreachableNode's information. The processing DYMO router removes the forwarding route androute, sets the broken flagflag, and a timer for ROUTE_DELETE is set to ROUTE_DELETE_TIMEOUT for each UnreachableNode.Address found using longest prefix matching that meet all of the following conditions: 1. The UnreachableNode.Address is a unicast address. 2. The Route.NextHopAddress is the same as the RERR IP.SourceAddress. 3. The Route.NextHopInterface is the same as the interface on which the RERR was received. 4. The Route.SeqNum is zero (0), unknown, OR the UnreachableNode.SeqNum is zero (0), unknown, OR Route.SeqNum - UnreachableNode.SeqNum <= 0 (using signed 16-bit arithmetic). During processing if Route.SeqNum is zero (0) or unknown and Unreachable.SeqNum exists in the RERR, then Route.SeqNum can be set to Unreachable.SeqNum. Setting Route.SeqNum can reduce future RRER processing and forwarding. Each UnreachableNode that did not result in a broken route is removed from the RERR, since propagation of this information will not result in any benefit. Any other information (AddTLVs) associated with the removed address(es) is also removed. After processing if Route.SeqNum is known and an Unreachable.SeqNum is not included in the RERR, then Route.SeqNum (i.e. Unreachable.SeqNum) can be added to the RERR. Including Unreachable.SeqNum can reduce future RRER processing and forwarding. If no UnreachableNode addresses remain in the RERR, no other processing is required and the RERR is discarded. If this RERR's MsgHdr.HopLimit is greater than one (1) and at least one unreachable node address remains in the RERR, then the updated RERR is sent to the IP.DestinationAddress LL MANET ROUTERS. 5.6. Unknown Message & TLV Types If a message with an unknown type is received, the message is discarded. If a message contains TLVs of an unknown type, a node ignores these during processing. The processing node can remove these TLVs from any resulting transmitted messages. The behavior for unknown TLV types should be administratively configurable. 5.7. Advertising Network Addresses Any DYMO router advertises a network address by using a PREFIX_LENGTH TLV [I-D.ietf-manet-packetbb]. Any nodes (other than the advertising DYMO router) within the advertised prefix SHOULD NOT participate in the DYMO protocol directly and these nodes MUST be reachable by forwarding packets to the DYMO router advertising connectivity. Nodes other than the advertising DYMO router that do participate in DYMO must forward the DYMO control packets to the advertising DYMO router. For example, A.B.C.1 with a prefix length of 24 indicates all nodes with the matching A.B.C.X are reachable through the DYMO router with address A.B.C.1. 5.8. Simple Internet Attachment and Gatewaying Simple Internet attachment consists of a stub network of MANET routerrouters connected to the Internet via a single Internet gateway node. DYMO can operate with multiple gateways, but such behavior is not specified in this document. The gateway is responsible for responding to RREQs for TargetNodes outside its configured DYMO prefix, as well as delivering packets to destinations outside the MANET. /--------------------------\ / Internet \ \ / \------------+-------------/ Gateway's | Advertised | A.B.C.X/24 Prefix | +-----+-----+ | DYMO | /------| Internet |--------\ / | Gateway | \ / | A.B.C.1 | \ | +-----------+ | | DYMO Region | | | | +--------------+ | | | DYMO Router | | | | A.B.C.2 | | | +--------------+ | | +--------------+ | | | DYMO Router | | | | A.B.C.3 | | \ +--------------+ / \ / \---------------------------/ Figure 7: Simple Internet AttachamentAttachment Example DYMO routers wishing to be reachable from nodes in the Internet MUST have IP addresses within the gateway's configured and advertised prefix. Given a node with a globally routeable address or care-of address handled by the gateway, the gateway is responsible for routing and forwarding packets received from the Internet destined for nodes inside its MANET. When DYMO router within the MANET want to send messages to nodes in the Internet, they simply issue RREQ for those IP.DestinationAddresses. The gateway is responsible for responding to RREQ on behalf of the Internet destinations and maintaining their associated sequence number. For an Internet gateway and other DYMO routers that maintain the sequence number on behalf of other nodes, these routers must be administratively configurable to know the IP addresses for which they must generate DYMO messages and maintain OwnSeqNum. 5.9. Multiple Interfaces DYMO may be used with multiple interfaces; therefore, the particular interface over which packets arrive must be known whenever a packet is received. Whenever a new route is created, the interface through which the Route.Address can be reached is also recorded in the route table entry. When multiple interfaces are available, a node transmitting a packet with IP.DestinationAddress set to LL MANET ROUTERS SHOULD send the packet on all interfaces that have been configured for DYMO operation. Similarly, DYMO routers should subscribe to LL MANET ROUTERS on all their DYMO interfaces. 5.10. Packet/Message Generation Limits To avoid congestion, a node's rate of packet/message generation should be limited. The rate and algorithm for limiting messages is left to the implementor and should be administratively configurable. Messages should be discarded in the following order of preferences RREQ, RREP, and finally RERR. 6. Configuration Parameters and Other Administrative Options Suggested Parameter Values +------------------------------+------------------------+ | Name | Value | +------------------------------+------------------------+ | MAX_HOPLIMIT | 10 hops | | NET_TRAVERSAL_TIME | 1000 milliseconds | | ROUTE_TIMEOUT | 5 seconds | | ROUTE_AGE_MIN_TIMEOUT | NET_TRAVERSAL_TIME | | ROUTE_AGE_MAX_TIMEOUT | 60 seconds | | ROUTE_NEW_TIMEOUT | ROUTE_TIMEOUT | | ROUTE_USED_TIMEOUT | ROUTE_TIMEOUT | | ROUTE_DELETE_TIMEOUT | 2 * ROUTE_TIMEOUT | | ROUTE_RREQ_WAIT_TIME | 2 * NET_TRAVERSAL_TIME | | RREQ_TRIES | 3 tries | | UNICAST_MESSAGE_SENT_TIMEOUT | 1 second | +------------------------------+------------------------+ Table 2 These suggested values work well for small and medium well connected networks with infrequent topology changes. These parameters should be administratively configurable for the network where DYMO is used. Ideally, for networks with frequent topology changes the DYMO parameters should be adjusted using either experimentally determined values or dynamic adaptation. For example, in networks with infrequent topology changes ROUTE_USED_TIMEOUT may be set to a much larger value. In addition to the parameters above several administrative options exist. The following table enumerates several of the options and suggested values. Suggested Options Settings +-------------------------------------+----------------------------+ | Name | Value | +-------------------------------------+----------------------------+ | RESPONSIBLE_ADDRESSES | Self or Prefix | | DYMO_INTERFACES | User Specified | | INCLUDE_INFORMATION | Yes-SeqNum,Dist,Prefix | | APPEND_ADDRESS | Yes - RREQ & RREP | | APPEND_OWN_ADDRESS_INCREMENT_SEQNUM | Yes for RREQ | | GENERATE_RERR_IMMEDIATELY | No | | RERR_INCLUDE_ALL_UNREACHABLES | Yes | | UNKNOWN_TYPE_HANDLING | Ignore | | BUFFER_SIZE_PACKETS | 50 packets | | BUFFER_SIZE_BYTES | 1500 * BUFFER_SIZE_PACKETS | +-------------------------------------+----------------------------+ Table 3 7. IANA Considerations DYMO requires a UDP port number to carry protocol packets - MANET [I-D.ietf-manet-iana]. DYMO also requires the link-local multicast address LL MANET ROUTERS [I-D.ietf-manet-iana]. This section specifies several messages types, message tlv-types, and address tlv-types. Future types will be allocated using standard actions as described in [RFC2434]. 7.1. DYMO Message Type Specification DYMO Message Types +------------------------+----------+ | Name | Type | +------------------------+----------+ | Route Request (RREQ) | 10 - TBD | | Route Reply (RREP) | 11 - TBD | | Route Error (RERR) | 12 - TBD | +------------------------+----------+ Table 4 7.2. Packet and Message TLV Type Specification Packet TLV Types +-------------------+------+--------+-------------------------------+ | Name | Type | Length | Value | +-------------------+------+--------+-------------------------------+ | Unicast Response | 10 - | 0 | Indicates to the processing | | Request | TBD | | node that the previous hop | | | | | (IP.SourceAddress) expects a | | | | | unicast message within | | | | | UNICAST_MESSAGE_SENT_TIMEOUT. | | | | | Any unicast packet will serve | | | | | this purpose, and it MAY be | | | | | an ICMP REPLY message. If a | | | | | message is not sent, then the | | | | | previous hop may assume that | | | | | the link is unidirectional | | | | | and may blacklist the link to | | | | | this node. | +-------------------+------+--------+-------------------------------+ Table 5 7.3. Address Block TLV Specification Address Block TLV Types +----------------+-------+--------+---------------------------------++----------------+------+---------+---------------------------------+ | Name | Type | Length | Value | +----------------+-------+--------+---------------------------------++----------------+------+---------+---------------------------------+ | DYMOSeqNum | 10 - | 16 bits | The DYMO sequence num | | | TBD | bits(2 | associated with this address. | | | | bytes) | The sequence number may be the | | | | | last known sequence number. | | Distance | 11 - | 8 bitsup to | A metric of the distance | | | TBD | 16 bits | traversed by the information | | | | (2 | associated with this address. | | | | bytes) | | | MaxAge | 12 - | | The maximum amount of time that | | | TBD | | information can be maintained | | | | | before being deleted. This TLV | | | | | conforms to | | | | | [I-D.ietf-manet-timetlv] | | | | | VALIDITY_TIME TLV, except that | | | | | the TLV is attached to | | | | | addresses. | +----------------+-------+--------+---------------------------------++----------------+------+---------+---------------------------------+ Table 6 8. Security Considerations Currently, DYMO does not specify any special security measures. In situations where confidentiality o DYMO messages is important, traditional cryptographic techniques can be applied. Securing routing information integrity will likely require DYMO routers to authenticate DYMO messages upon reception. Also, since routing information is distributed hop-by-hop, DYMO routers will also likely need to authenticate the source of the routing information, the source's DYMO router. Note that is important that any confidentiality and integrity algorithms used permit multiple receivers to process the message, since all DYMO messaging is multicast. 9. Acknowledgments DYMO is a descendant of the design of previous MANET reactive protocols, especially AODV [RFC3561] and DSR [RFC4728]. Changes to previous MANET reactive protocols stem from research and implementation experiences. Thanks to Elizabeth Belding-Royer for her long time authorship of DYMO. Additional thanks to Luke Klein- Berndt, Pedro Ruiz, Fransisco Ros, Koojana Kuladinithi, Ramon Caceres, Thomas Clausen, Christopher Dearlove, Seung Yi, Romain Thouvenin, Tronje Krop, Henner Jakob andJakob, Alexandru PetrescuPetrescu, Christoph Sommer, Cong Yuan, and Lars Kristensen for reviewing of DYMO, as well as several specification suggestions. 10. References 10.1. Normative References [I-D.ietf-manet-iana] Chakeres, I., "Internet Assigned Numbers Authority (IANA)"IANA Allocations for theMobile Ad hoc NetworksNetwork (MANET) Working Group", draft-ietf-manet-iana-05Protocols", draft-ietf-manet-iana-06 (work in progress), JuneOctober 2007. [I-D.ietf-manet-packetbb] Clausen, T., "Generalized MANET Packet/Message Format", draft-ietf-manet-packetbb-07draft-ietf-manet-packetbb-10 (work in progress), JulyOctober 2007. [I-D.ietf-manet-timetlv] Clausen, T. and C. Dearlove, "Representing multi-value time in MANETs", draft-ietf-manet-timetlv-01draft-ietf-manet-timetlv-02 (work in progress), JulyAugust 2007. [RFC1812] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812, June 1995. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, February 2006.10.2. Informative References [I-D.ietf-manet-jitter] Clausen, T., "Jitter considerations in MANETs", draft-ietf-manet-jitter-01draft-ietf-manet-jitter-02 (work in progress), JulyAugust 2007. [I-D.ietf-manet-nhdp] Clausen, T., "MANET Neighborhood Discovery Protocol (NHDP)", draft-ietf-manet-nhdp-04 (work in progress), July 2007. [Johnson96] Johnson, D. and D. Maltz, "Dynamic Source Routing (DSR) in Ad hoc Networks", In Mobile Computing, Chapter 5, pp. 153- 181, 1996.[Perkins99] Perkins, C. and E. Belding-Royer, "Ad hoc On-Demand Distance Vector (AODV) Routing", Proceedings of the 2nd IEEE Workshop on Mobile Computing Systems and Applications, New Orleans, LA, pp. 90-100, February 1999. [RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On- Demand Distance Vector (AODV) Routing", RFC 3561, July 2003. [RFC4728] Johnson, D., Hu, Y., and D. Maltz, "The Dynamic Source Routing Protocol (DSR) for Mobile Ad Hoc Networks for IPv4", RFC 4728, February 2007. Authors' Addresses Ian D Chakeres Motorola Bangalore India Email: email@example.com URI: http://www.ianchak.com/ Charles E. 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