Mobile Ad hoc Networks Working I. Chakeres Group Boeing Internet-Draft C. Perkins Expires:
December 22, 2006April 5, 2007 Nokia June 20,October 2, 2006 Dynamic MANET On-demand (DYMO) Routing draft-ietf-manet-dymo-05draft-ietf-manet-dymo-06 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 December 22, 2006.April 5, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract The Dynamic MANET On-demand (DYMO) routing protocol is intended for use by mobile nodes in wirelesswireless, multihop networks. It offers adaptation to changing network topology and determines unicast routes between nodes within the network on-demand. Table of Contents 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Route Table Entry . . . . . . . . . . . . . . . . . . . . 6 4.2. DYMO Messages . . . . . . . . . . . . . . . . . . . . . . 7 4.2.1. Generalized MANET Packet and Message Structure . . . . 7 4.2.2. Routing MessageMessages (RM) . . . . . . . .- RREQ & RREP . . . . . . . . . 8 4.2.3. Route Error (RERR) . . . . . . . . . . . . . . . . . . 10 5. Detailed Operation . . . . . . . . . . . . . . . . . . . . . . 12 5.1. DYMO Sequence Numbers . . . . . . . . . . . . . . . . . . 12 5.1.1. Maintaining A Node's Own Sequence Number . . . . . . . 12 5.1.2. Incrementing a Sequence NumberOwnSeqNum . . . . . . . . . . . . . . . . 13 5.1.3. Sequence NumberOwnSeqNum Rollover . . . . . . . . . . . . . . . . . . 13 5.1.4. Actions After Sequence NumberOwnSeqNum Loss . . . . . . . . . . . . . 13 5.2. DYMO Routing Table Operations . . . . . . . . . . . . . . 13 5.2.1. Judging NewRouting Information's Usefulness . . . . . . . 13 5.2.2. Creating or Updating a Route Table Entry with FreshNew Routing Information . . . . . . . . . . . . . . . . . . . . . 1415 5.2.3. Route Table Entry Timeouts . . . . . . . . . . . . . . 15 5.3. Routing MessageMessages . . . . . . . . . . . . . . . . . . . . . 1517 5.3.1. RREQ Creation . . . . . . . . . . . . . . . . . . . . 1517 5.3.2. RREP Creation . . . . . . . . . . . . . . . . . . . . 1618 5.3.3. RM Processing . . . . . . . . . . . . . . . . . . . . 1618 5.3.4. Adding Additional Routing Information to a RM . . . . 1820 5.4. Route Discovery . . . . . . . . . . . . . . . . . . . . . 1820 5.5. Route Maintenance . . . . . . . . . . . . . . . . . . . . 1921 5.5.1. Active Link Monitoring . . . . . . . . . . . . . . . . 1921 5.5.2. Updating Route Lifetimes during Packet Forwarding . . 2021 5.5.3. Route Error Generation . . . . . . . . . . . . . . . . 2022 5.5.4. Route Error Processing . . . . . . . . . . . . . . . . 2122 5.6. General DYMO Packet andUnknown Message Processing . . . . . . . . 21 5.6.1. Receiving Packets . . . . . . . . . .& TLV Types . . . . . . . . 21 5.6.2. Processing Unknown Message and TLV Types. . . . . . . 2123 5.7. Advertising Network Addresses . . . . . . . . . . . . . . . . . . . . 2223 5.8. Simple Internet Attachment and Gatewaying . . . . . . . . 2224 5.9. Multiple Interfaces . . . . . . . . . . . . . . . . . . . 2325 5.10. PacketPacket/Message Generation Limits . . . . . . . . . . . . . . . . . 2425 6. Configuration Parameters and Other Administrative Options . . . . . . . . . . . . . . . . . . . 2425 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 2426 7.1. DYMO Message Type Specification . . . . . . . . . . . . . 2527 7.2. Packet TLV Type Specification . . . . . . . . . . . . . . 2527 7.3. Address Block TLV Specification . . . . . . . . . . . . . 2628 8. Security Considerations . . . . . . . . . . . . . . . . . . . 2628 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 2729 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 2729 10.1. Normative References . . . . . . . . . . . . . . . . . . . 2729 10.2. Informative References . . . . . . . . . . . . . . . . . . 2830 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 2931 Intellectual Property and Copyright Statements . . . . . . . . . . 3032 1. Overview The Dynamic MANET On-demand (DYMO) routing protocol enables reactive, multihop routing between participating nodes that wish to communicate. The basic operations of the DYMO protocol are route discovery and route management. During route discovery the originating node initiates dissemination of a Route Request (RREQ) throughout the network to find the target node. During this dissemination process, each intermediate node records a route to the originating node. When the target node receives the RREQ, it responds with a Route Reply (RREP) unicastsent hop-by-hop toward the originating node. Each node that receives the RREP records a route to the target node, and then the RREP is unicast toward the originating node. When the originating node receives the RREP, routes have then been established between the originating node and the target node in both directions. In order to react to changes in the network topology nodes maintain their routes and monitor their links.links over which traffic is moving. When a data packet is received for forwarding if a route is not known or link thatthe route is no longer availablebroken, then the source of the packet is notified. A Route Error (RERR) is sent to the packet source to indicate the current route is broken. OnceWhen the source receives the RERR, it canknows that it must perform route discovery if it still has packets to deliver. DYMO uses sequence numbers as they have been provento ensure loop freedom [Perkins99]. Sequence numbers enable nodes to determine the order of DYMO route discovery messages, thereby avoiding use of stale routing information. 2. Applicability The DYMO routing protocol is designed for mobile ad hoc networks in small, medium, and large node populations.networks. DYMO handles alla wide variety of mobility ranges.patterns by dynamically determining routes on-demand. DYMO can handle variousalso handles a wide variety of traffic patterns, butpatterns. In large networks DYMO is mostbest suited for sparsetraffic sources and destinations. DYMO is designed for networkscenarios where trust is assumed, since it depends onnodes properly forwarding traffic to the next hop toward the destination on behalfcommunicate with only a portion of other the source.nodes. DYMO is applicable to memory constrained devices, since little routing state needs to be maintained. Only routing information related to active sources and destinations must be maintained, as opposedin contrast to other routing protocols where routingthat require routing information to all destinations or a large population destinations mustnodes within the autonomous system be maintained. 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 keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT","SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC2119 [RFC2119]. This document uses some terminology from packetbb[I-D.ietf-manet- packetbb]. This document defines the following terminology: DYMO Sequence Number (SeqNum) A DYMO Sequence Number is maintained by each node. This sequence number is used by other nodes to identify the freshnessorder of relatedrouting information generated by a node and to ensure loop-free routes. Hop Count (HopCnt) The number of IP hops a message or piece of information must traverse to reach the node holding this information. Originator (Orig)has traversed. Originating Node (OrigNode) The originatororiginating node is the node that created 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 node generates and disseminates a RERR to disseminateindicate that it does not have valid route to a particular destination,one or set ofmore particular destinations. Route Reply (RREP) Upon receiving a RREQ during route discovery, the target node generates a Route Reply (RREP).A RREP is used to disseminate routing information, oninformation about how to reach the target,RREQ target node, to nodes between the RREQ target node and the RREQ originator. Route Request (RREQ) A node (the RREQ originator) generates a RREQ to discover a valid route to a particular destination, called the target.RREQ target node. A RREQ also disseminatesprovides routing information on how to reach the originator of the RREQ. Target Node (TargetNode) The target node is the ultimate destination of a message. For RREQ the target node is the desired destination.destination, the destination for which a valid route does not exist. For RREP the target node is the originator of the RREQ. ValidRREQ originator. Type-Length-Value structure (TLV) A generic way to represent information, see packetbb [I-D.ietf- manet-packetbb]. Forwarding Route A valid route is a knownroute where the Route.ValidTimeoutthat is greater than the current time. Valid routes may beused to forward data. When describing DYMO messages, information founddata packets. Forwarding routes are generally maintained in the: IP header is proceeded with 'IP.' UDP header is proceeded with 'UDP.' packetbb message header is proceeded with 'MsgHdr.' packetbb message TLVs is proceeded with 'MsgTLV.' packetbb address blocks is proceeded with 'AddBlk.' packetbb address block TLVs is proceeded with 'AddTLV.'a forwarding information base (FIB) or the kernel forwarding/routing table. 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. The number zero (0) is reserved and can be used to indicate that the field value for this routing entry is unknown or invalid. A routingConceptually, a route table entry has the following fields: Route.Address The IP destination address of the node associated with the routing table entry. Route.SeqNum The DYMO SeqNum associated with this routing information. Route.NextHopAddress The IP address of the next node on the path toward the Route.Address. Route.NextHopInterface The interface used to send packets toward the Route.Address. Route.ValidTimeout The time at which a route table entryRoute.Broken A flag indicating whether this Route is no longer valid. Route.DeleteTimeout If the current timebroken. This flag is after Route.DeleteTimeoutset if the corresponding routing table entry MUST be deleted. The followingnext hop becomes unreachable or in response to processing a RERR (see Section 5.5.4). The following fields are optional: Route.HopCnt The number of intermediate node hops traversed before reaching the Route.Address node. Route.IsInternetGateway 1-bit selector indicatingRoute.HopCnt assists in determining whether the Route.Addressreceived routing information is a an Internet gateway, see Section 5.8.superior to existing known information. 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 is setmay be considered to zero (0), unknown, orhave a prefix length equal to the address length in bits, this address is a host address. The definition of Route.Prefix is different for gateways; entries with Route.IsInternetGateway set to one (1), seeSection 5.8. Route.Used 1-bit selector indicating whether this Route has been used to forward data toward the destination.(in bits). Not including thisoptional information may result in sub-optimal performance,cause performance degradation, but it iswill not required for correctcause the protocol operation.to operate incorrectly otherwise. 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 packetbb [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 AllDYMO messages conform to the generalized packet and message format as described in[I-D.ietf-manet-packetbb].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 TBD. AllMost DYMO messages are sent with the IP destination address set to the link local multicast address LL_ALL_MANET_ROUTER unless otherwise stated. The IP TTL (IP HopUnicast DYMO messages specified in this document are sent with the IP destination set to the Route.NextHopAddress of the route to the target node. The IP TTL (IP Hop Limit) field for allDYMO messages is set to one (1).(1) for all messages specified in this document. The length of an IP addresses (32-bitsaddress (32 bits for IPv4 and 128-bits128 bits for IPv6) inside a DYMO messages are dependentmessage depends on the IP packet header.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, IPv4 addresses are carried in IPv6 as specified in [RFC3513]. 4.2.2. Routing MessageMessages (RM) - RREQ & RREP Routing Messages (RM)(RMs) are used to disseminate routing information. There are two DYMO message types that are RM,considered to be routing messages (RMs): RREQ and RREP. They contain the same information,very similar information and function, but have slightly different processing rules. The fundamentalmain difference between the two messages areis that RREQ messages requiresolicit a response; whileRREP, 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.DestinationAddress The IP address of the packet destination. For RREQ the IP.DestinationAddress is set to LL_ALL_MANET_ROUTERS. For RREP the IP.DestinationAddress is set to the NextHopAddress toward the TargetNode. UDP.DestinationPort The UDP destination port is set to TBD. MsgHdr.HopLimit The remaining number of hops this message mayis allowed to traverse. AddBlk.Target.AddressAddBlk.TargetNode.Address The IP address of the message target.target node. In a RREQ the target node is the unknown destination.destination for which a forwarding route does not exist and route discovery is being performed. In a RREP the target node is the RREQ originator. Only oneThe target node address can be marked asis the first address in the target. AddBlk.Orig.Addressrouting message. AddBlk.OrigNode.Address The IP address of the message originator.node originating this message. This address is in an address block and not in the message header to allow for address compression and additional AddTLVs. AddTLV.Orig.SeqNumThis address is the second address in the message for RREQ. AddTLV.OrigNode.SeqNum The DYMO sequence number of the message originator.originating node. A RM may optionally include the following information: AddTLV.Target.SeqNumAddTLV.TargetNode.SeqNum The last known DYMO sequence number of the target. If the AddTLV.Target.SeqNum is settarget node. AddTLV.TargetNode.HopCnt The last known HopCnt to zero (0), then onlythe destination may respond to this RREQ.target node. AddBlk.AdditionalNode.Address The IP address of an additional node that can be reached via the node adding this information. Each AdditionalNode.Address must have an associated SeqNum in the message.address TLV block. AddTLV.AdditionalNode.SeqNum The DYMO sequence number of thean additional intermediate node's routing information. AddTLV.Node.HopCnt The number of IP hops to reach the associated Node.Address. This field is incremented at each intermediate hop, for each node except the target node's HopCnt information. AddTLV.Node.Prefix The Node.Address is a network address ([I-D.ietf-manet-packetbb]). AddTLV.Node.IsGateway This AddTLV indicates that the Internet is reachable via this node. That is, all nodes outside this Node'swith a particular prefix are reachable via the advertising Node. AddTLV.Node.IsTarget If the target is not the first address in the address blocks, this AddTLV is used to indicate the target. AddTLV.Node.IsOriginator In the event that the originator is not the second address in the address blocks, this AddTLV is used to indicate the originator. AddTLV.AdditionalNode.IsOffPath This AddTLV is used to indicate that a node is not on the path between the originator and the target. AddTLV.Node.Ignore If the information associated with this Node.Address should not be used create or update a route, this flag is set. Not including this optional information may result in sub-optimal performance, but it is not required for correct protocol operation.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.DestinationAddress=LL_ALL_MANET_ROUTERS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... UDP Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Port=TBD | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Message Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RREQ-type | Resv |0|0|1| msg-size=24msg-size=23 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-hoplimit | msg-hopcnt | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Message Body - Message TLV Block +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-tlv-block-size=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Message Body - Address Block +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Number Addrs=2 |0|HeadLength=24||0|HeadLength=3 | Head : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Head(cont) | Target.Tail | Orig.Tail | TLV-blk-size : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : size=7 (cont) | +-+-+-+-+-+-+-+-+ ...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Message Body - Address TLVsBlock TLV Block +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |DYMOSeqNum-type| Resv |1|0|0|0| Index Start=1 | Index Stop=1| tlv-block-size=6 |DYMOSeqNum-type|Resv |0|1|0|0|0| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | tlv-length=16Index-start=1 | tlv-length=2 | Orig.SeqNum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 4.2.3. Route Error (RERR) A RERR aremessage is used to disseminate the information that a validroute is not available for a particular destination,one or set of destinations.more particular IP addresses. RERR creation and processing are described in Section 5.5.3 and Section 188.8.131.52.5. A RERR requires the following information: IP.DestinationAddress The IP address of the packet destination.is set to LL_ALL_MANET_ROUTERS. UDP.DestinationPort The UDP destination port is set to TBD. MsgHdr.HopLimit The remaining number of hops this message mayis allowed to traverse. AddBlk.Unreachable.AddressAddBlk.UnreachableNode.Address The IP address of an Unreachable Node.UnreachableNode. Multiple Unreachable Addressesunreachable addresses may be included. Ifincluded in a SeqNum for this address is not included, it is assumed to be unknown.RERR. A Route Error may optionally include the following information: AddTLV.Unreachable.SeqNumAddTLV.UnreachableNode.SeqNum The last known DYMO sequence number of the Unreachable Node. AddTLV.Node.Ignoreunreachable node. If the information associated with Node.Address shoulda SeqNum for an address is not included, it is assumed to be usedunknown. This case occurs when a node receives a message to invalidate routes, this flag is set.forward 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.DestinationAddress=LL_ALL_MANET_ROUTERS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... UDP Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Port=TBD | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Message Header +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RERR-type | Resv |0|0|1| msg-size=16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-hoplimit | msg-hopcnt | msg-tlv-block-size=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Address BlockMessage Body +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-tlv-block-size=0 |Number Addrs=1 |0|HeadLength=0|1|HeadLength=4 | Unreachable.Addr :+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Unreachable.Addr (cont)| TLV-blk-size=0Unreachable.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,information and ensure loop freedom. 5.1.1. Maintaining A Node's Own Sequence Number DYMO requires athat each node in the network to maintain its own DYMO sequence number (OwnSeqNum), a 16-bit unsigned integer. The circumstances for a node to incrementing its OwnSeqNum are described in Section 5.3. 5.1.2. Incrementing a Sequence NumberOwnSeqNum When a node increments its OwnSeqNum (as described in Section 5.3) it MUST do so by treating the sequence number value as if it wasan unsigned number. A node starts with its OwnSeqNum equal to one (1). The sequence number zero (0) is reserved and is used in several DYMO data structures to represent an unknown sequence number.reserved. 5.1.3. Sequence NumberOwnSeqNum Rollover If the sequence number has been assigned to be the largest possible number representable as a 16-bit unsigned integer (i.e., 65535), then the sequence number MUST beis 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 Sequence NumberOwnSeqNum Loss A node canshould 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_PERIODROUTE_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 not 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 period. RERR generation is described in Section 5.5.3.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 NewRouting Information's Usefulness Given a routingroute table entry (Route.SeqNum, Route.HopCnt, and Route.ValidTimeout)Route.Broken) and new routing information for a particular node in a RM (Node.SeqNum, Node.HopCnt, and RM message type - RREQ/RREP), the quality of the new routing information is evaluated to determine its usefulness. The following comparisons are performed in order:Incoming routing information is classified as follows: 1. Stale If Node.SeqNum - Route.SeqNum < 0 (using signed 16-bit arithmetic) the 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-proneLoop-possible If Node.SeqNum == Route.SeqNum the information maybe loop-prone,may cause loops if used; in this case additional information must be examined. If Route.HopCnt is unknownor set to zero (0), then the routing information is loop- prone. Likewise, ifNode.HopCnt is unknown or set tozero (0), then the routing information is loop-prone.loop-possible. If Node.HopCnt > Route.HopCnt + 1, then the routing information is loop-prone.loop-possible. Using loop-proneloop-possible routing information is not allowed, since doing so might result inotherwise routing loops.loops may be formed. (Node.SeqNum == Route.SeqNum) AND ((Node.HopCnt is unknown) OR (Route.HopCnt is unknown) OR (Node.HopCnt > Route.HopCnt +1)) 3. Inferior If Node.SeqNum == Route.SeqNum the information may be inferior,inferior; additional information must be examined. If Node.HopCnt >= to Route.HopCnt, the current route is valid (by examining Route.ValidTimeoutnot Broken, and the current time),message is a RREQ, then the new information is inferior ifinferior. If Node.HopCnt > Route.HopCnt. IfRoute.HopCnt + 1, the current route is valid,not Broken and the message is RREP, then the new information is also inferiorinferior. Inferior routes will not cause routing loops if Node.HopCntintroduced, but should not be used since better information is already available. (Node.SeqNum == Route.SeqNum) AND (Route.Broken == false) AND ((Node.HopCnt > Route.HopCnt) AND (RM is RREQ)) OR ((Node.HopCnt > Route.HopCnt + 1) AND this RM(RM is a RREQ.RREP))) 4. FreshSuperior Routing information that does not match any of the above criteria is loop-free and better than the information existing in the routing table. Only thisThis type of information is used to update the routing table. For completeness, the following other cases are possible: (Node.SeqNum - Route.SeqNum > 0) OR ((Node.SeqNum == Route.Seqnum) AND ((Node.HopCnt == Route.HopCnt + 1) OR (Node.HopCnt == Route.HopCnt)) AND (((Route.Broken == true) AND (RM is RREQ)) OR ((Route.Broken == false) AND (RM is RREP)))) OR ((Node.HopCnt < Route.HopCnt + 1) AND (Route.Broken == false)) 5.2.2. Creating or Updating a Route Table Entry with FreshNew Routing Information If fresh routing information is received, the routingThe 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 (IP.SourceAddress),(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.ValidTimeoutRoute.HopCnt is set to the current time + ROUTE_VALID_TIMEOUT,Node.HopCnt, 6. if known, the Route.HopCntRoute.Prefix is set to the Node.HopCnt, 7.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 Route.Prefixminimum 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 Node.Prefix, 8. the Route.IsInternetGatewaymaximum delete timeout (ROUTE_AGE_MAX). ROUTE_AGE_MAX is set to Node.AddTLV.MaxAge if addressincluded; otherwise, ROUTE_AGE_MAX is an Internet Gateway. Unknown values areset to zero (0). If a valid route exists to Node.Address atROUTE_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 to fulfillforwarding any incoming data packets for Route.Address. This route also fulfills any outstanding RREQ.route discovery attempts for Node.Address. 5.2.3. Route Table Entry Timeouts Before using184.108.40.206. Minimum Delete Timeout (ROUTE_AGE_MIN) When a routingnode transmits a RM, other nodes expect the transmitting node to have a forwarding route to the RM originator. After updating a route table entry its timeouts mustentry, it should be examined. Ifmaintained for at least ROUTE_AGE_MIN. Failure to maintain the current timeinformation 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. 220.127.116.11. Maximum Delete Timeout (ROUTE_AGE_MAX) Sequence number information is time sensitive, and must be deleted after Route.DeleteTimeouta time in order to avoid conflicts due to reboots and rollovers. When a node has lost its sequence number (e.g, due to daemon reboot or node replacement) the correspondingnode must wait until routing table entry MUSTinformation associated with its IP address and sequence number are no longer maintained by other nodes in the network to ensure loop-free routing. After the ROUTE_AGE_MAX timeout a route must be deleted. IfAll information about the current timeroute is later thandeleted upon ROUTE_AGE_MAX timeout. If a forwarding route exists it is also removed. 18.104.22.168. 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 entry's Route.ValidTimeout,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 stale and cannot be usedset to ROUTE_DELETE_TIMEOUT. 22.214.171.124. Recently Used Timeout (ROUTE_USED) When a route packets. The information in invalid entriesis stillused for filling fieldsto forward data packets, this timer is set to expire after ROUTE_USED_TIMEOUT. This operation is also discussed in outgoing RM with last known values.Section 5.5.2. If a route has not been used recently, then a timer for ROUTE_DELETE is set to ROUTE_DELETE_TIMEOUT. 126.96.36.199. 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 MessageMessages 5.3.1. RREQ Creation When a node creates a RREQ it SHOULD increment its OwnSeqNum by one (1) according to the rules specified in (Section 5.1.2). Fist,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 nodes might not consider this information useful if they have better information already. First, the node adds the AddBlk.Target.AddressAddBlk.TargetNode.Address to the RM. If a previous value of the Target.SeqNumTargetNode.SeqNum is known (from an existinga routing table entry), it SHOULDshould be placed in AddTLV.Target.SeqNum.AddTLV.TargetNode.SeqNum. If a Target.SeqNumTargetNode.SeqNum is not included, it is assumed to be unknown by processing nodes and only the target is allowed to respond. A Target.SeqNum of zero (0) MAY be set to indicate that any node with valid routing information about this destination can respond to this RREQ if the node is so enabled, though the process for doing so is not described in this document.nodes. Similarly, if a previous value of the Target.HopCntTargetNode.HopCnt is known, it SHOULDshould be placed in AddTLV.Target.HopCnt.AddTLV.TargetNode.HopCnt. Otherwise, the HopCntAddTLV.TargetNode.HopCnt is not included and assumed unknown by processing nodes. These AddTLVs associated with the target SHOULDnode should be set to maximumimprove protocol efficiency, but they may be omitted to reduce message size.omitted. Next, the node adds AddBlk.Orig.AddressAddBlk.OrigNode.Address to the RM and the AddTLV.Orig.SeqNumAddTLV.OrigNode.SeqNum (OwnSeqNum) in an address block TLV. The Orig.AddressOrigNode.Address is this node's primary addresses/identifier. The Orig.Addressaddresses/identifier, and it must be a routable IP address. This information will be used by nodes to create a route toward the OrigNode and enable delivery of a RREP. Other AddTLVs for the originator SHOULDOrigNode should be set to maximumimprove protocol efficiency, but they may be omittedomitted. If OrigNode.HopCnt is included it is set to reduce message size.zero (0). The MsgHdr.HopCnt is set to zero (0). The MsgHdr.HopLimit SHOULDshould be set to NET_DIAMETER, but MAYmay be set smaller. For RREQ, the MsgHdr.HopLimit MAYmay 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 the LL_ALL_MANET_ROUTERS. 5.3.2. RREP Creation When a node creates a RREP in response to a RREQ, it MUST incrementincrements its OwnSeqNum underby one (1) according to the following conditions: o Target.SeqNum is not includedrules specified in the message, OR o Target.SeqNum is zero (0), OR o Target.SeqNum - OwnSeqNum > 0 (using 16-bit signed arithmetic), OR o Target.SeqNum == OwnSeqNum AND Target.HopCnt is unknown, OR o Target.SeqNum ==Section 5.1.2. If OwnSeqNum AND Orig.HopCntis unknown, OR o Target.SeqNum == OwnSeqNum AND Target.HopCnt (the last know hop count value) < Orig.HopCnt (thenot incremented the routing information might be considered stale. In this case, the RREP would not reach the originating node. Note: We are currently discussing and investigating mechanisms to avoid incrementing the sequence number of hops traversed bybefore issuing a route reply. An update to this RREQbehavior will likely happen in the next revision. Avoiding incrementation of the sequence number when issuing a RREP is an important mechanism to reachreduce the target). First,unnecessary devaluing of good routing information, and the ability to issue intermediate node replies. Further when intermediate node replies are coupled with expanding ring search, route discovery cost can be further reduced. The node then adds the AddBlk.Target.AddressAddBlk.TargetNode.Address to the RM.RREP. The Target.AddressTargetNode.Address is copied from the incoming RREQ AddBlk.Orig.Address.AddBlk.OrigNode.Address. Next, the node adds the AddBlk.Orig.AddressAddBlk.OrigNode.Address to the RMRREP and the AddTLV.Orig.SeqNumAddTLV.OrigNode.SeqNum (OwnSeqNum) in an address block TLV. The Orig.AddressOrigNode.Address is copied from the incoming RREQ AddBlk.Target.Address.AddBlk.TargetNode.Address. Other AddTLVs for the originatorOrigNode and target SHOULDTargetNode should be set to maximumimprove protocol efficiency, but they may be omittedomitted. If OrigNode.HopCnt is included it is set to reduce message size.zero (0). The MsgHdr.HopCnt is set to zero (0). The MsgHdr.HopLimit is set to NET_DIAMETER. 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. RM Processing When a RM is received the MsgHdr.HopLimit is decremented by one (1) and MsgHdr.HopCnt is incremented by one (1). For each address (except the TargetNode) in the RM that includes AddTLV-HopCnt information except the target and those addresses tagged with the AddTLV-Ignore,AddTLV.HopCnt information, the AddTLV-HopCntAddTLV.HopCnt information is incremented by one (1). Next, this node checks whether its routing table has an entry to the AddBlk.Orig.AddressAddBlk.OrigNode.Address using longest-prefix matching [RFC1812]. If a route does not exist, 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 routingroute table entry does exists, the new node's information is compared with the route table entry following the procedure described in Section 5.2.1. If the new node's routing information is considered fresh,superior, the route table entry is updated as described in Section 5.2.2. If the routing information for the originator is not fresh then this RM must be discarded and no furtherAfter processing of this message is performed. Ifthe originator'sOrigNode's routing information was considered fresh,information, then each address that is not the target and is not flagged with the Ignore address-block-tlv SHOULDTargetNode should be considered for creating and updating routes. If routing table space is limited, only the routing information about the originator is required.Creating and updating routes forto other locationsnodes can eliminate RREQ for those destination,IP destinations, in the event that data needs to be forwarded to these destinationsthe IP destination(s) in the near future. For each of thesethe additional addresses considered, if 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 routingroute table entry exists, the new node's information is compared with the route table entry following the procedure described in Section 5.2.1. If the new node's routing information is considered fresh,superior, the route table entry is updated as described in Section 5.2.2. If the routing information for an Node.AddressAdditionalNode.Address is not considered fresh,superior, then if MUST beit is removed from the RM. Removing this information ensures that non-freshthe information is not propagated. IfAt 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 receiving node is the targetTargetNode AND this RM is a RREQ, then this node responds with a RREP. This node createsThe procedure for creating a new RREP asis described in Section 5.3.2. After processing a RM or creating a new RM, a node MAYcan append additional routing information to the RM, according to the processprocedure described in Section 5.3.4. The additional routing information willcan help reduce route discoveries at the expense of increased message size. If this RM's MsgHdr.HopLimit is greater than one (1), this node is not the target,TargetNode, AND this RM is a RREQ, then the current RM (altered by the processprocedure defined above) SHOULD beis sent to the LL_ALL_MANET_ROUTERS IP.DestinationAddress. If this RM's MsgHdr.HopLimit is greater than one (1), this node is not the target,TargetNode, AND this RM is a RREP, then the newcurrent RM SHOULD beis sent to the Route.NextHopAddress for the RREP's Target.Address.TargetNode.Address. If no forwarding route exists to Target.Address, then a RERR is issued to the originator of the RREP. If this node is the target,TargetNode of the current RM's informationRM, the current RM is not retransmitted. 5.3.4. Adding Additional Routing Information to a RM Appending routing information willcan alleviate route discovery attempts to the nodes whose information is included, if other nodes use this information to update their routing tables. Nodes MAYcan append routing information to a RM, and should if the node believebelieves that this additional routing information will alleviate future RREQ. This option should be administratively controlled.configured. Prior to appending theirits own address to a RM, a node MUSTshould increment its OwnSeqNum as defined in Section 5.1.2. Then the node appends its IP address (AddBlk-Address) andIf OwnSeqNum (AddTLV-SeqNum). It MAY also append otheris 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 its address, such as prefix and/or that it isan Internet Gateway.RM in transit should be administratively configured. If included,included the Node.HopCnt for this node is included, it is set to one (1). Routingzero (0). Additional information about other nodes MAYthe address(es) can also be added. If this information is included, it must be flagged with the AddTLV.AdditionalNode.IsOffPath. Note an address may appear only once in a message's address blocks. Prior to adding any address, the message is searched for existing entries. If an existing entry exists, this entry will have the informationappended, such as this node's routing table information (created or updated while processing the RM) and therefore no update is necessary. In the eventa newly appended address already has an AddTLV-Ignore flag set, it is removed.PREFIX_LENGTH AddTLV. 5.4. Route Discovery A node creates and sends a RREQ (described in Section 5.3.1) to discover a route to a particular destination (target). The IP.DestinationAddress(TargetNode) for this RREQ is set to the LL_ALL_MANET_ROUTERS. Then the RM is transmitted.which it does not currently have a forwarding route. After issuing a RREQ, the originating nodeOrigNode waits for a route to be created to the target.TargetNode. If a route is not foundcreated within RREQ_WAIT_TIME milliseconds,RREQ_WAIT_TIME, this node MAYmay again try to discover a route by issuing another RREQ. To reduce congestion in a network, repeated attempts at route discovery for a particular target SHOULDnode should utilize a binaryan exponential backoff. TheFor example, the first time a node issues a RREQ, it waits RREQ_WAIT_TIME millisecondsfor a route to the target.target node. If a route is not found within that time, the node 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 SHOULDshould be buffered. This buffer SHOULDshould have a fixed limited size (BUFFER_SIZE_PACKETS or BUFFER_SIZE_BYTES) and discardolder data packets should be discarded first. If a route discovery has been attempted RREQ_TRIES times without receiving a route to the target,target node, all data packets destined for the corresponding target node are dropped from the buffer and a Destination Unreachable ICMP message SHOULDshould be delivered to the application. 5.5. Route Maintenance A RERR MUST be issued if a data packet is received and it cannot be delivered to the next hop,hop when no forwarding route exists; RERR generation is described in Section 5.5.3. In addition to inability to deliver a data packet, A RERR MAYshould be issued immediately after detecting a broken link of an activeforwarding route to quickly notify nodes that a link break occurred and that certain routes are no longer available. If athe route with the broken link has not been used, aused recently (indicated by ROUTE_USED), the RERR SHOULD NOTshould not be generated unless generation is expected to reduce future traffic.generated. 5.5.1. Active Link Monitoring Nodes MUST monitor links on active routes that are being used.next hop links on forwarding routes. This maymonitoring can be accomplished by one or several mechanisms. Including: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) the detecting node MUST set the Route.ValidTimeout tomust remove the current time for all activeaffected forwarding routes utilizing the(those with an unreachable next hop). The node also flags these routes as Broken. For each broken link.route a timer for ROUTE_DELETE is set to ROUTE_DELETE_TIMEOUT. 5.5.2. Updating Route Lifetimes during Packet Forwarding To avoid route timeouts for active routes,removing forwarding routes that are being used, a node SHOULD update the Route.ValidTimeoutset a timeout (ROUTE_USED) to ROUTE_USED_TIMEOUT for the IP.SourceAddressroute to bethe current time + ROUTE_VALID_TIMEOUTIP.SourceAddress upon receiving a data packet. This route's Route.Used bitIf a timer for ROUTE_DELETE is alsoset, if implemented.it is removed. To avoid route timeouts for active routes,removing forwarding routes that are being used, a node SHOULD update the Route.ValidTimeoutset a timeout (ROUTE_USED) to ROUTE_USED_TIMEOUT for the IP.DestinationAddressroute to bethe current time + ROUTE_VALID_TIMEOUTIP.DestinationAddress upon successfully transmittingsending a packet to the next hop. This route's Route.Used bitdata packet. If a timer for ROUTE_DELETE is also set.set, it is removed. 5.5.3. Route Error Generation When a data packet is received for a destination without a valid routingroute table entry, a RERR MUST be generated. When a RREP is being transmitted and no activeforwarding route to the targetTargetNode exists, a RERR MUST be generated. A RERR informs the IP.SourceAddress or RREP.OrigNode.Address that the route does not exist, and a route is no longer available, or is now invalid. Innot available through this node. When creating a new RERR, the address of first unreachable node (IP.DestinationAddress from the data packet)packet or RREP.TargetNode.Address) is inserted. If a value for the unreachable node's SeqNum (AddTLV-SeqNum)(AddTLV.UnreachableNode.SeqNum) is known, it SHOULDshould be placed in the RERR. The MsgHdr.HopLimit is set to NET_DIAMETER. The MsgHdr.HopCnt is set to one (1). Additional unreachable nodesUnreachableNodes that requiredrequire the same unavailable link (routes with the same Route.NextHopAddress and Route.NextHopInterface) MAYmay be added to the RERR. The SeqNum if know SHOULDknown should also be included. Appending unreachable nodeUnreachableNode information notifies each processing node of additional routes that are no longer available. This option should be administratively configured. If SeqNum information is not known or not included in the RERR, all nodes processing the routing informationRERR will assume their routing information associated with the unreachable nodeUnreachableNode is no longer valid. The RERR is sent to the IP.DestinationAddress LL_ALL_MANET_ROUTERS. Sending the RERR to the LL_ALL_MANET_ROUTERS address notifies the maximum number ofnearby nodes ofthat might depend on the now broken link. The packet or message that forced generation of this RERR is discarded. 5.5.4. Route Error Processing When a node processes a RERR, it processes each unreachableUnreachableNode's information. The processing node address. It setsremoves the Route.ValidTimeout toforwarding route and sets the current timebroken flag for each AddressUnreachableNode.Address found using longest prefix matching that meet all of the following conditions: 1. The Route.NextHopAddress is the same as the RERR IP.SourceAddress. 2. The Route.NextHopInterface is the same as the interface on which the RERR was received. 3. The Route.SeqNum is zero (0), unknown, OR the Node.SeqNumUnreachableNode.SeqNum is zero (0), unknown, OR Node.SeqNumUnreachableNode.SeqNum - Route.SeqNum <= 0 (using signed 16-bit arithmetic). Each unreachable nodeUnreachableNode that did not result in a change to Route.ValidTimeoutbroken 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 addressesaddress(es) is also removed. If no unreachable nodeUnreachableNode addresses remain,remain in the RERR, no furtherother processing is performed. If this RERR's MsgHdr.HopLimit is greater than one (1)required and at least one unreachable node address remains in the RERR, thenthe RERR is sent to the IP.DestinationAddress LL_ALL_MANET_ROUTERS. Addresses marked with AddTLV-Ignore should remain in the RERR. 5.6. General DYMO Packet and Message Processing 5.6.1. Receiving Packets When a packet is received, its PktTLV are first examined. Next each messagediscarded. If this RERR's MsgHdr.HopLimit is examinedgreater than one (1) and processedat least one unreachable node address remains in order. Each message's headers are first examined. Next,the MsgTLV are examined. Finally, each messageRERR, then the updated RERR is processed accordingsent to its MsgHdr.type. 5.6.2. Processingthe IP.DestinationAddress LL_ALL_MANET_ROUTERS. 5.6. Unknown Message and& TLV Types To allow future extensions, DYMO uses bits from the semantics fields of PktTLV, Message, MsgTLV, and AddTLV [I-D.ietf-manet-packetbb]. Note [I-D.ietf-manet-packetbb] does not currently support this functionality. The semantic bits have the following names and characteristics for nodes that do not understand the type. RemoveIf the Semantics.Remove-bita message with an unknown type is set, this information SHOULD be removed from the message. Discard Ifreceived, the Semantics.Discard-bitmessage is set, thisdiscarded. If a message SHOULD not be processed further and it should not be propagated. In the casecontains TLVs of PktTLVs if the Semantics.Discard-bit is set, no messagesan unknown type, a node ignores these during processing. The processing node can remove these TLVs from the packetany resulting transmitted messages. The behavior for unknown TLV types should be processed or propagated.administratively configured. 5.7. Advertising Network Addresses Any node MAYcan advertise a network address by using a Prefix tlvPREFIX_LENGTH TLV [I-D.ietf-manet-packetbb]. Any nodes (other than the advertising node) within the advertised Prefixprefix SHOULD NOT participate in the MANETDYMO protocol directly and these nodes MUST be reachable by forwarding packets to the node advertising connectivity. Nodes other than the advertising node that do participate in DYMO must forward the DYMO control packets to the advertising node. 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 node with address A.B.C.1. The meaning of the Prefix field is altered for theroute to an Internet gateway; Route.IsInternetGateway is one (1). If the route refers to an Internet gateway, its Prefix in association with the IP address indicates that all nodes outside that subnet are reachable via the Internet gateway node. For example, a route to a Internet gateway with IP address A.B.C.1 and a prefix of 24 indicates that all nodes with an IP address NOT matching A.B.C.X are reachable via this node.5.8. Simple Internet Attachment and Gatewaying Simple Internet attachment consists of a network of MANET nodes connected to the Internet via a single Internet gateway node. The gateway is responsible for responding to RREQs for targetstarget nodes outside its configured MANET subnet,DYMO prefix, as well as delivering packets to destinations outside the MANET. /--------------------------\ / Internet \ \ / \------------+-------------/ MANET SubnetGateway's | Advertised | A.B.C.X Prefix | +-----+-----+ | MANETDYMO | /------| Internet |------\ / | Gateway | \ / | A.B.C.1 | \ | +-----------+ | | MANETDYMO Region | | | | +------------+ | | | MANETDYMO Node | | | | A.B.C.2 | | | +------------+ | | +------------+ | | | MANETDYMO Node | | | | A.B.C.3 | | \ +------------+ / \ / \-------------------------/ Figure 3:7: Simple Internet Attachament Example MANETDYMO nodes wishing to be reachable from nodes in the Internet MUST have IP addresses within the gateway's configured and advertised MANET subnet.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 subnet. Since manyMANET. When nodes may commonly wish to communicate with the gateway,within the gateway SHOULD indicateMANET want to nodes that it is a gateway by using the gateway tlv in any RM transmitted. The Internet Gateway tlv indicatessend messages to nodes in the MANET that the Node.AddressInternet, they simply issue RREQ for those IP.DestinationAddresses. The gateway is attachedresponsible for responding to RREQ on behalf of the Internet destinations and is capable of routing data packets to allmaintaining their associated sequence numbers. For an Internet gateway and other nodes outside ofthat maintain the sequence number on behalf of other nodes, these routers must be administratively configured MANET subnet, defined byto know the Node.AddressIP addresses for which they must generate DYMO messages and Node.Prefix fields.maintain OwnSeqNum. 5.9. Multiple Interfaces It is likely thatDYMO will often be used with multiple wirelessinterfaces; 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_ALL_MANET_ROUTERS SHOULD send the packet on all interfaces that have been configured for DYMO operation. 5.10. PacketPacket/Message Generation Limits To avoid congestion, a node SHOULD NOT transmit more than RATE_LIMIT controlnode's rate of packet/message generation should be limited. The rate and algorithm for limiting messages per second. RREQ packets SHOULDis left to the implementor and should be administratively configured. Messages should be discarded before RREP or RERR packets.in the following order of preferences RREQ, RREP, and finally RERR. 6. Configuration Parameters and Other Administrative Options Suggested Parameter Values +------------------------+-------------------------++------------------------------+------------------------+ | Name | Value | +------------------------+-------------------------++------------------------------+------------------------+ | NET_DIAMETER | 10 hops | | RATE_LIMITNET_TRAVERSAL_TIME | 101000 milliseconds | | ROUTE_VALID_TIMEOUTROUTE_TIMEOUT | 5000 milliseconds5 seconds | | ROUTE_DELETE_TIMEOUTROUTE_AGE_MIN_TIMEOUT | 5 * ROUTE_VALID_TIMEOUTNET_TRAVERSAL_TIME | | ROUTE_DELETE_PERIODROUTE_AGE_MAX_TIMEOUT | 660 seconds | | ROUTE_NEW_TIMEOUT | ROUTE_TIMEOUT | | ROUTE_USED_TIMEOUT | ROUTE_TIMEOUT | | ROUTE_DELETE_TIMEOUT | 2 * ROUTE_VALID_TIMEOUTROUTE_TIMEOUT | | ROUTE_RREQ_WAIT_TIME | 1000 milliseconds2 * NET_TRAVERSAL_TIME | | RREQ_TRIES | 3 tries | | UNICAST_MESSAGE_SENT_TIMEOUT | +------------------------+-------------------------+ Table1 second | +------------------------------+------------------------+ Table 2 These suggested values work well for small and medium well connected networks with infrequenceinfrequent topology changes. For larger networks orThese parameters should be administratively configured for the network where DYMO is used. Ideally, for networks with frequent topology changes the defaultDYMO parameters should be adjusted using either experimentally determined values or dynamic adaptation. For example, in networks with infrequent topology changes ROUTE_VALID_TIMEOUTROUTE_USED_TIMEOUT may be set to a much larger value. It is assumed that all nodes inIn addition to the network shareparameters above several administrative options exist. The following table enumerates several of the same parameter settings. Different parameter valuesoptions and suggested values. Suggested Options Settings +-------------------------------------+----------------------------+ | Name | Value | +-------------------------------------+----------------------------+ | RESPONSIBLE_ADDRESSES | Self or Prefix | | DYMO_INTERFACES | User Specified | | INCLUDE_INFORMATION | Yes-SeqNum,HopCnt,Prefix | | APPEND_ADDRESS | Yes - RREQ & RREP | | APPEND_OWN_ADDRESS_INCREMENT_SEQNUM | Yes for ROUTE_VALID_TIMEOUT or ROUTE_DELETE_TIMEOUT in addition to arbitrary packet delays may result in frequent route breaks or in extreme cases routing loops.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 - TBD. DYMO also requires the link-local multicast address LL_ALL_MANET_ROUTERS; IPv4 TBD, IPv6 TBD.TBD [I-D.chakeres-manet-iana]. This section alsospecifies several messages types, message tlv- types,tlv-types, and address tlv-types. Future types will be allocated using standard actions as described in [RFC2434]. 7.1. DYMO Message Type Specification The following address block TLV.DYMO Message Types +------------------------+----------+ | Name | Type | +------------------------+----------+ | Route Request (RREQ) | 10 - TBD | | Route Reply (RREP) | 11 - TBD | | Route Error (RERR) | 12 - TBD | +------------------------+----------+ Table 24 7.2. Packet TLV Type Specification Packet TLV Types +-------------------+------+--------+-------------------------------+ | Name | Type | Length | Value | +-------------------+------+--------+-------------------------------+ | Unicast Response | TBD |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 35 7.3. Address Block TLV Specification Address Block TLV Specification Overview +----------------------+------+--------+----------------------------+Types +----------------+------+---------+---------------------------------+ | Name | Type | Length | Value | +----------------------+------+--------+----------------------------++----------------+------+---------+---------------------------------+ | DYMOSeqNum | 10 - | 16 bits | The DYMO sequence num | | | TBD | bits| associated with this address. | | | | | address.The sequence | | | | |number may be the last| | | | | last known sequence number. | | HopCount | 11 - | 8 bits | The number of hops | | | TBD | |traversed by the| | | TBD | | the information associated with | | | | | withthis address. | | IsInternetGatewayMaxAge | 12 - | 0 bits | Usde to indicate that this | | | TBD | | node is an Internet | | | | | Gateway | | IsOriginator | 13 - | 0 bits | Used to indicate that this | | | TBD |Any | node is the OriginatorThe maximum number of | | | | | the RM. | | IsTarget | 14 - | 0 bits | Used to indicate this node | | |TBD | length | is the target of the DYMO | | | | | message | | Ignore | 15 - | 0 | Used to indicatemilliseconds that this | | | TBD | | addresses should not bethe | | | | | processed normally;associated routing information | | | | | instead it shouldcan be kept before being | | | | | ignored.deleted. | +----------------------+------+--------+----------------------------++----------------+------+---------+---------------------------------+ Table 46 8. Security Considerations Currently, DYMO does not specify any special security measures. 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, DYMO 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 DYMO 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, RM 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, while slightly less dangerous,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 DYMO 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. 9. Acknowledgments DYMO is a descendant of the design of previous MANET reactive protocols, especially AODV [RFC3561] and DSR [Johnson96]. 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, andThomas ClausenClausen, Christopher Dearlove, and Seung Yi for reviewing of DYMO, as well as several specification suggestions. 10. References 10.1. Normative References [I-D.ietf-manet-packetbb] Clausen, T., "Generalized MANET Packet/Message Format", draft-ietf-manet-packetbb-02 (work in progress), July 2006. [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. [RFC3513] Hinden, R. and S. Deering, "Internet Protocol Version 6 (IPv6) Addressing Architecture", RFC 3513, April 2003. [RFC3561] Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc On- Demand Distance Vector (AODV) Routing", RFC 3561, July 2003. 10.2. Informative References [I-D.ietf-manet-nhdp] Clausen, T., Dearlove, C., and J. Dean,[I-D.chakeres-manet-iana] Chakeres, I., "MANET Neighborhood Discovery Protocol", draft-ietf-manet-nhdp-00IANA Needs", draft-chakeres-manet-iana-01 (work in progress), JuneSeptember 2006. [I-D.ietf-manet-packetbb][I-D.ietf-manet-nhdp] Clausen, T., Dearlove, C., Dean, J., and C. Adjih, "Generalized MANET Packet/Message Format", draft-ietf-manet-packetbb-01"MANET Neighborhood Discovery Protocol (NHDP)", draft-ietf-manet-nhdp-00 (work in progress), June 2006. [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. Authors' Addresses Ian Chakeres Boeing Phantom Works The Boeing Company P.O. Box 3707 Mailcode 7L-49 Seattle, WA 98124-2207 USA Email: email@example.com Charlie Perkins Nokia Research Center 313 Fairchild Drive Mountain View, CA 94043 USA Phone: +1-650-625-2986 Fax: +1-650-625-2502 Email: firstname.lastname@example.org@nokia.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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