Mobile Ad hoc Networks Working I. Chakeres Group Boeing Internet-Draft C. Perkins Expires:
September 6,December 22, 2006 Nokia March 5,June 20, 2006 Dynamic MANET On-demand (DYMO) Routing draft-ietf-manet-dymo-04draft-ietf-manet-dymo-05 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 September 6,December 22, 2006. 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 wireless 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 3.4. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 8 3.1.6 4.1. Route Table Entry . . . . . . . . . . . . . . . . . . . . 8 3.2.6 4.2. DYMO Messages . . . . . . . . . . . . . . . . . . . . . . 10 220.127.116.11 4.2.1. Generalized MANET Packet and Message Structure . . . . 10 18.104.22.168 4.2.2. Routing Message (RM) . . . . . . . . . . . . . . . . . 10 22.214.171.124 4.2.3. Route Error (RERR) . . . . . . . . . . . . . . . . . . 12 4.10 5. Detailed Operation . . . . . . . . . . . . . . . . . . . . . . 14 4.1.12 5.1. DYMO Sequence Numbers . . . . . . . . . . . . . . . . . . . . . 14 126.96.36.199 5.1.1. Maintaining aA Node's Own Sequence Number . . . . . . . . . . . . 14 188.8.131.52 5.1.2. Incrementing a Sequence Number . . . . . . . . . . . . 14 184.108.40.206 5.1.3. Sequence Number Rollover . . . . . . . . . . . . . . . 14 220.127.116.11 5.1.4. Actions After Sequence Number Loss . . . . . . . . . . 14 4.2.13 5.2. DYMO Routing Table Operations . . . . . . . . . . . . . . 14 4.2.1. Creating or13 5.2.1. Judging New Routing Information's Usefulness . . . . . 13 5.2.2. Updating a Route Table Entry fromwith Fresh Routing MessageInformation . . . . . . . . . . . . . . . . . . . . . 14 18.104.22.168.2.3. Route Table Entry Timeouts . . . . . . . . . . . . . . 16 4.3.15 5.3. Routing Message . . . . . . . . . . . . . . . . . . . . . 16 4.3.1. Routing Message15 5.3.1. RREQ Creation . . . . . . . . . . . . . . . 16 4.3.2. Routing Message Processing .. . . . . 15 5.3.2. RREP Creation . . . . . . . . 16 4.3.3. Appending Additional Routing Information to an Existing Routing Message. . . . . . . . . . . . 16 5.3.3. RM Processing . . . 17 4.4. Route Discovery. . . . . . . . . . . . . . . . . 16 5.3.4. Adding Additional Routing Information to a RM . . . . 18 22.214.171.124. Route MaintenanceDiscovery . . . . . . . . . . . . . . . . . . . . . 18 4.5.1. Active Link Monitoring5.5. Route Maintenance . . . . . . . . . . . . . . . . 18 4.5.2. Updating Route Lifetimes. . . . 19 5.5.1. Active Link Monitoring . . . . . . . . . . . . . . . . 19 126.96.36.199.5.2. Updating Route Lifetimes during Packet Forwarding . . 20 5.5.3. Route Error Generation . . . . . . . . . . . . . . . . 19 188.8.131.52 5.5.4. Route Error Processing . . . . . . . . . . . . . . . . 20 4.6.21 5.6. General DYMO Packet and Message Processing . . . . . . . . 21 4.6.1. Packet Processing5.6.1. Receiving Packets . . . . . . . . . . . . . . . . . . 21 4.6.2. Generic5.6.2. Processing Unknown Message Pre-processingand TLV Types . . . . . . . 21 5.7. Network Addresses . . . . . 21 4.6.3. Processing Unknown Message and TLV Types. . . . . . . 21 4.6.4. Generic Message Post-processing. . . . . . . . 22 5.8. Simple Internet Attachment and Gatewaying . . . 21 4.6.5. DYMO Control Packet Transmission. . . . . 22 5.9. Multiple Interfaces . . . . . . 21 4.7. Routing Prefix. . . . . . . . . . . . . 23 5.10. Packet Generation Limits . . . . . . . . . 21 4.8. Simple Internet Attachment and Gatewaying. . . . . . . . 22 4.9. Multiple Interfaces24 6. Configuration Parameters . . . . . . . . . . . . . . . . . . . 22 4.10. Packet Generation Limits24 7. IANA Considerations . . . . . . . . . . . . . . . . . . . 23 5. Configuration Parameters. . 24 7.1. DYMO Message Type Specification . . . . . . . . . . . . . 25 7.2. Packet TLV Type Specification . . . . 24 6. IANA Considerations. . . . . . . . . . 25 7.3. Address Block TLV Specification . . . . . . . . . . . 25 7.. . 26 8. Security Considerations . . . . . . . . . . . . . . . . . . . 26 8.9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 9.10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28 9.1.27 10.1. Normative References . . . . . . . . . . . . . . . . . . . 28 9.2.27 10.2. Informative References . . . . . . . . . . . . . . . . . . 28 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29 Intellectual Property and Copyright Statements . . . . . . . . . . 30 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) unicast 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. When a data packet is received for a route or link that is no longer available the source of the packet is notified. A Route Error (RERR) is sent to the packet source to indicate the current route is broken. Once the source receives the RERR, it can perform route discovery if it still has packets to deliver. In order to enable extension of the base specification, DYMO uses the generalized MANET packet and message format . Additionally, by following the defined default behavior for nodes not understanding a particular type of information, future enhancements are handled in an understood and predetermined fashion.DYMO uses sequence numbers as they have been proven to ensure loop freedom .[Perkins99]. Sequence numbers enable nodes to determine the order of DYMO route discovery messages, thereby avoiding use of stale routing information. All2. Applicability The DYMO messages conformrouting protocol is designed for mobile ad hoc networks in small, medium, and large node populations. DYMO handles all mobility ranges. DYMO can handle various traffic patterns, but is most suited for sparse traffic sources and destinations. DYMO is designed for network where trust is assumed, since it depends on nodes properly forwarding traffic to the generalized MANET message andnext hop toward the destination on behalf of the source. DYMO is applicable to memory constrained devices, since little routing state needs to be maintained. Only routing information related to active destinations must be maintained, as opposed to other routing protocols where routing information to all destinations or a large population destinations must 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. 3. Terminology The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT","SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are transmitted via UDP on port TBD. 2. Terminologyto be interpreted as described in RFC2119 [RFC2119]. This document defines the following terminology: DYMO Sequence Number (SeqNum) A DYMO Sequence Number is 16-bit numbermaintained by each node, and itnode. This sequence number is used to identify the freshness of related routing information and to ensure loop-free routes. Hop Count (HopCnt) The number of IP hops a particularmessage or piece of information has traversed. IP Destination Address (IPDestinationAddress) The destination of a packet, determined by examining the IP header. IP Source Address (IPSourceAddress) The source of a packet, determined by examining the IP header. MANETcast Packet transmissionmust traverse to all neighboring MANET routers. MANETcast packets should be sent with an IPDestinationAddress of IPv4 TBD (IPv6 TBD),reach the MANETcastAddress.node holding this information. Originator (Orig) The Originatororiginator is the node that created a RoutingDYMO Message in an effort to disseminate and possibly learn new routinginformation. PrefixRoute Error (RERR) A Prefix indicatesnode generates a RERR to disseminate that an address isit does not have valid route to a network address, rather than a host address. If a Prefix is omitted, the address is assumed to be a host address. Routing Message (RM) A DYMO message that is used to distribute routing information. Route Invalidation Disabling the useparticular destination, or set of a route; causing it to be unavailable for forwarding data.destinations. Route Reply (RREP) Upon receiving a RREQ during route discovery, the target node generates a Route Reply (RREP). A RREP is used to disseeminatedisseminate routing informationinformation, on how to reach the Target. A RREP is a RM with a unicast IPDestinationAddress, indicating that this RM istarget, to be unicast hop-by-hop towardnodes between the Target. Route Error (RERR) A node generates a Route Error (RERR) to disseminate that it does not have correct routing information about a particular destination, or set of destinations. A RERR is most often generated in response to a request to forward a data packet for whichtarget and the current node does not have a valid route.RREQ originator. Route Request (RREQ) A node generates a Route Request (RREQ)RREQ to discover a valid route to a particular destination (Target).destination, called the target. A RREQ is used to disseminatealso disseminates routing information on how to reach the Originatororiginator of the RREQ. A RREQ is simply a RM with the MANETcastAddress in the IPDestinationAddress field of the IP packet, causing distribution to all neighboring DYMO routers.Target The Targettarget node is the ultimate destination of a message. For RREQ this will bethe target is the desired destination. For RREP this will bethe Originatortarget is the originator of the RREQ. Valid Route A valid route is a known route where the Route.ValidTimeout is greater than the current time. 3.Valid routes may be used to forward data. When describing DYMO messages, information found 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.' 4. Data Structures 184.108.40.206. 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. o Route.DestAddress o Route.DeleteTimeout o Route.HopCnt o Route.IsGateway o Route.NextHopAddress o Route.NextHopInterface o Route.Prefix o Route.SeqNum o Route.ValidTimeout These fields are defined as follows: Route Node Address (Route.DestAddress)The IP address of the node associated with the routing table entry. Route Delete Timeout (Route.DeleteTimeout) If the time currentnumber zero (0) is after Route.DeleteTimeout the correspondingreserved and can be used to indicate that the field value for this routing entry is unknown or invalid. A routing table entry MUST be deleted. Route Hop Count (Route.HopCnt)has the following fields: Route.Address The numberIP destination address of intermediate node hops before reachingthe Route.DestAddress. Route Is Gateway (Route.IsGateway) 1-bit selector indicating whethernode associated with the Route.DestAddress is a gateway, see Section 4.8. Route Next Hop Address (Route.NextHopAddress)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.DestAddress. Route Next Hop Interface (Route.NextHopInterface)Route.Address. Route.NextHopInterface The interface used to send packets toward the Route.DestAddress. Route Prefix (Route.Prefix) 8-bit field that specifiesRoute.Address. Route.ValidTimeout The time at which a route table entry is no longer valid. Route.DeleteTimeout If the sizecurrent time is after Route.DeleteTimeout the corresponding routing table entry MUST be deleted. The following fields are optional: Route.HopCnt The number of intermediate node hops traversed before reaching the subnet reachable throughRoute.Address node. Route.IsInternetGateway 1-bit selector indicating whether the Route.DestAddress,Route.Address is a an Internet gateway, see Section 220.127.116.11. Route.Prefix Indicates that the associated address is a network address, rather than a host address. The definitionvalue is the length of the Prefix fieldnetmask/ prefix. If prefix is set to zero (0), unknown, or 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.IsGatewayRoute.IsInternetGateway set to one (1), see Section 4.8.seeSection 5.8. Route.Used 1-bit selector indicating whether this Route Sequence Number (Route.SeqNum) The sequence number of the Route.DestAddress, zero (0) if unknown. Route.ValidTimeout The time at which a route table entry is scheduledhas been used to be invalidated. The routing table entry is no longer considered valid ifforward data toward the current timedestination. Not including this optional information may result in sub-optimal performance, but it is after Route.ValidTimeout. 3.2.not required for correct protocol operation. 4.2. DYMO Messages 18.104.22.168.2.1. Generalized MANET Packet and Message Structure All DYMO messages conform to the generalized packet and message format as described in . 3.2.2. Routing Message (RM) Routingin[I-D.ietf-manet-packetbb]. All DYMO messages are used tosent using UDP to the destination port TBD. All 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 Hop Limit) field for all DYMO messages is set to one (1). The length of IP addresses (32-bits for IPv4 and 128-bits for IPv6) inside DYMO messages are dependent on the IP packet header. 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 Message (RM) Routing Messages (RM) are used to disseminate routing information. TheThere are two DYMO message types that are RM, RREQ and RREP and they haveRREP. They contain the same general format.information, but have slightly different processing rules. The fundamental difference between the two messages are that RREQ messages require a response,response; while a RREP are responsesis the response to RREQ. Routing messageRM creation and processing are described in Section 4.3. Example Simple RREQ/RREP Routing Message 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-type | RSRV |U|N|0|1| msg-size | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-ttl | msg-hopcnt | msg-tlv-block-size=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Head Length | Head |Number Tails=2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TailOrig | TailTarget | tlv-block-size | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |DYMOSEQNUM-type| TLV Length | Orig.SeqNum.: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ :.Orig.SeqNum | Target.SeqNum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 o5.3. A RM conform torequires the generalizedfollowing information: IP.DestinationAddress The IP address of the packet destination. MsgHdr.HopLimit The remaining number of hops this message format. o msg-type = DYMO-RREQ or DYMO-RREP o msg-semantics * RM indicate inclusionmay traverse. AddBlk.Target.Address The IP address of msg-ttl and msg-hop-count in msg- header-info, by setting bit 1 o msg-header-info * RM contains msg-ttl * RM contains msg-hop-count o add-block entries * RM contain 1 and only 1 address marked as Originator - If no address is marked asthe originatormessage target. In RREQ the first addresstarget is assumed to bethe Originator * ifunknown destination. In RREP the RM is unicast (the IPDestinationAddresstarget is a unicast address), RM contain 1 and only 1the RREQ originator. Only one address can be marked as Target (Target) - if nothe target. AddBlk.Orig.Address The IP address is markedof the secondmessage originator. This address is assumedin an address block and not in the message header to beallow for address compression and additional AddTLVs. AddTLV.Orig.SeqNum The DYMO sequence number of the Target o add-tlv *message originator. A RM containmay optionally include the following information: AddTLV.Target.SeqNum The last known DYMO Sequence Numbersequence number of the Originator (Orig.SeqNum) in a DYMO Sequence Number tlv * RM should contain the SeqNum for each address.target. If the SeqNum is not included a value of Zero (0)AddTLV.Target.SeqNum is assumed. For the Target the SeqNum will be the Last Known SeqNum (Target.SeqNum) or Zero (0)set to indicate thatzero (0), then only the Target can reply * RM should contain the HopCnt for each address. If HopCnt is not included, it is assumeddestination may respond to this RREQ. AddBlk.AdditionalNode.Address The IP address of an additional node that can be zero (unknown). Forreached via the Targetnode adding this information. Each AdditionalNode.Address must have an associated SeqNum in the HopCnt should bemessage. AddTLV.AdditionalNode.SeqNum The DYMO sequence number of the Last Known HopCnt (Target.HopCnt) * RM should containadditional node's routing information. AddTLV.Node.HopCnt The number of IP hops to reach the associated Node.Address. AddTLV.Node.Prefix The Node.Address is a Prefix for eachnetwork address ([I-D.ietf-manet-packetbb]). AddTLV.Node.IsGateway This AddTLV indicates that the Internet is not a host address. If areachable via this node. That is, all nodes outside this Node's prefix are reachable via the advertising Node. AddTLV.Node.IsTarget If the target is not includedthe first address in conjunction with an address, it is assumed zero (host address only). For more information on advertising a Prefix see Section 4.7. * RM should contain a Gateway tlv for anthe address thatblocks, this AddTLV is a gateway. If gateway indicatorused to indicate the target. AddTLV.Node.IsOriginator In the event that the originator is not includedthe second address in association with an address,the address blocks, this AddTLV is assumedused 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 gateway. For moreroute, this flag is set. Not including this optional information on gateway operation see Section 4.8. 3.2.3. Route Error (RERR)may result in sub-optimal performance, but it is not required for correct protocol operation. Example Simple RERR MessageIPv4 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | rerr-msg-typeRREQ-type | RSRV |U|N|0|1| msg-sizeResv |0|0|1| msg-size=24 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | msg-ttlmsg-hoplimit | msg-hopcnt | msg-tlv-block-size=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |... Address Block +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Number Addrs=2 |0|HeadLength=24| Head Length |: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Head |Number Tails=1(cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Target.Tail | Tail1Orig.Tail | tlv-block-size |dymo-seqnum-typ|TLV-blk-size : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : size=7 (cont) | TLV Length+-+-+-+-+-+-+-+-+ ... Address TLVs +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |DYMOSeqNum-type| Resv |1|0|0|0| Index Start=1 | Tail1.SeqNumIndex Stop=1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | tlv-length=16 | Orig.SeqNum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 o1 4.2.3. Route Error (RERR) RERR conformare used to the generalized message format. o msg-type = DYMO-RERR o msg-semantics * RERR indicates inclusiondisseminate that a valid route is not available for a particular destination, or set of msg-ttl and msg-hop-count in msg- header-info, using bit 1 o msg-header-info * RERR contain msg-ttl *destinations. RERR contain msg-hop-count o add-block entries * All addressescreation and processing are considered unreachable unless marked otherwise o add-tlvs *described in Section 5.5.3 and Section 5.5.4. A RERR should contain SeqNum for each unreachable node. Ifrequires the following information: IP.DestinationAddress The IP address of the packet destination. MsgHdr.HopLimit The remaining number of hops this message may traverse. AddBlk.Unreachable.Address The IP address of an Unreachable Node. Multiple Unreachable Addresses may be included. If a SeqNum for this address is not included in the messageincluded, it is assumed to be zero (unknown) * RERR should contain the Last Known HopCnt for each unreachable node.unknown. A Route Error may optionally include the following information: AddTLV.Unreachable.SeqNum The DYMO sequence number of the Unreachable Node. AddTLV.Node.Ignore If the HopCnt isinformation associated with Node.Address should not included in the message it is assumed tobe zero (unknown) 4.used to invalidate routes, this flag is set. 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 Block +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Number Addrs=1 |0|HeadLength=0 | Unreachable.Addr : +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ : Unreachable.Addr (cont) | TLV-blk-size=0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 5. Detailed Operation 22.214.171.124. DYMO Sequence Numbers 4.1.1.DYMO sequence numbers allow nodes to judge the freshness of routing information, and ensure loop freedom. 5.1.1. Maintaining aA Node's Own Sequence Number DYMO requires a each node in the network to maintain its own DYMO sequence number (OwnSeqNum), a 16-bit unsigned integer. The circumstances for a node to changeincrementing its OwnSeqNum are described in Section 4.3.1. 126.96.36.199.3. 5.1.2. Incrementing a Sequence Number When a node increments its OwnSeqNum (as described in Section 4.3.1 and Section 4.3.2)5.3) it MUST do so by treating the sequence number value as if it was an unsigned number. The sequence number zero (0) is reserved and is used in several DYMO data structures to represent an unknown sequence number. 188.8.131.52.1.3. Sequence Number 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 be 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. 184.108.40.206.1.4. Actions After Sequence Number Loss A node SHOULDcan maintain its sequence number in persistent storage.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 sequence numberOwnSeqNum loss a node MUST wait for at least ROUTE_DELETE_PERIOD 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 RM.DYMO messages. If a data packet is received for forwarding to another destination during this waiting periodperiod, 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 220.127.116.11.5.3. At the end of the waiting period a node sets its sequence numberOwnSeqNum to one (1). 18.104.22.168. DYMO Routing Table Operations 4.2.1. Creating or Updating a Route Table Entry from5.2.1. Judging New Routing Message Information While processing a RM, as described in Section 4.3.2,Information's Usefulness Given a node checks itsrouting table for an entry to the Node.Address using longest- prefix matching . In the event that no matching entry is found, an entry is created. If a matchingentry is found, the(Route.SeqNum, Route.HopCnt, and Route.ValidTimeout) and new routing information about Node.Address containedfor a particular node in thisa RM is NOT stale if(Node.SeqNum, Node.HopCnt, and RM message type - RREQ/RREP), the resultquality of subtractingthe Route.SeqNum from Node.SeqNumnew routing information is equalevaluated to zero (0) usingdetermine its usefulness. The following comparisons are performed in order: 1. Stale If Node.SeqNum - Route.SeqNum < 0 (using signed 16-bit arithmetic but it SHOULD be disregarded if: oarithmetic) the Route.ValidTimeout has not passed and Node.HopCntinformation is greater thanstale. Using stale routing information is not allowed, since doing so might result in routing loops. 2. Loop-prone If Node.SeqNum == Route.SeqNum the information maybe loop-prone, additional information must be examined. If Route.HopCnt is unknown or equalset to Route.HopCnt, OR ozero (0), then the Route.ValidTimeout has passed androuting information is loop- prone. Likewise, if Node.HopCnt is greater than Route.HopCnt plus one (1).unknown or set to zero (0), then the routing information is loop-prone. If Node.HopCnt > Route.HopCnt + 1, then the routing information associated with this Node.Addressis stale or disregarded and this Node.Addressloop-prone. Using loop-prone routing information is not allowed, since doing so might result in routing loops. 3. Inferior If Node.SeqNum == Route.SeqNum the Originator then this DYMO message MUSTinformation may be dropped. For other Node.Addresses that are stale or disregarded, theinferior, additional information is simply removed frommust be examined. If the RM. Removing staleroute is valid (by examining Route.ValidTimeout and disregarded routing informations ensures that unusedthe current time), then the new information is not propagated further.inferior if Node.HopCnt > Route.HopCnt. If the route is valid, then the new information for Node.Addressis also inferior if Node.HopCnt == Route.HopCnt AND this RM is a RREQ. 4. Fresh Routing information that does not stale or disregarded, thenmatch any of the following actions occurabove criteria is loop-free and better than the information existing in the routing table. Only this type of information is used to update the routerouting table. 5.2.2. Updating a Route Table Entry with Fresh Routing Information If fresh routing information is received, the routing table entry for Node.Address:is populated with the following information: 1. the Route.HopCntRoute.Address is set to the Node.HopCnt,Node.Address, 2. the Route.IsGatewayRoute.SeqNum is set to the G-bit,Node.SeqNum, 3. the Route.NextHopAddress is set to the node that transmitted this DYMO packet (IPSourceAddress),(IP.SourceAddress), 4. the Route.NextHopInterface is set to the interface that this DYMO packet was received on, 5. the Route.PrefixRoute.ValidTimeout is set to Node.Prefix,,the current time + ROUTE_VALID_TIMEOUT, 6. the Route.SeqNumRoute.HopCnt is set to the Node.SeqNum,Node.HopCnt, 7. andthe Route.ValidTimeoutRoute.Prefix is set to the current time + ROUTE_TIMEOUT.Node.Prefix, 8. the Route.IsInternetGateway is set if address is an Internet Gateway. Unknown values are set to zero (0). If a valid route exists to Node.Address at this point, the route can be used to send any queued data packets and to fulfill any outstanding route requests. 4.2.2.RREQ. 5.2.3. Route Table Entry Timeouts Before using a routing table entry its timeouts must be examined. If the current time is after Route.DeleteTimeout the corresponding routing table entry MUST be deleted. If the current time is later than a routing entry's Route.ValidTimeout, the route is stale and it is notcannot be used to route packets. The information in invalid entries canis still beused for filling fields in outgoing RM with last known values. 4.3. Routing Message 22.214.171.124.3. Routing Message 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 4.1.2.(Section 5.1.2). Fist, the node adds the AddBlk.Target.Address to the RM. If a previous value of the Target.SeqNum is known (from an existing routing table entry), it SHOULD be placed in AddTLV.Target.SeqNum. If a Target.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. Similarly, if a previous value of the Target.HopCnt is known, it SHOULD be placed in AddTLV.Target.HopCnt. Otherwise, the HopCnt is not included and assumed unknown by processing nodes. These AddTLVs associated with the target SHOULD be set to maximum protocol efficiency, but they may be omitted to reduce message size. Next, the node adds AddBlk.Orig.Address to the RM and the AddTLV.Orig.SeqNum (OwnSeqNum) in an address block TLV. The Orig.Address is this node's primary addresses/identifier. The Orig.Address must be a routable IP address. Other AddTLVs for the originator SHOULD be set to maximum protocol efficiency, but they may be omitted to reduce message size. The MsgHdr.HopCnt is set to zero (0). The MsgHdr.HopLimit SHOULD be set to NET_DIAMETER, 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. 5.3.2. RREP Creation When a node creates a RREP in response to a RREQ, it MUST increment its OwnSeqNum under the following conditions: o Target.SeqNum is greater than OwnSeqNumnot included in the message, OR o Target.SeqNum is equal tozero (0), OR o Target.SeqNum - OwnSeqNum > 0 (using 16-bit signed arithmetic), OR o Target.SeqNum == OwnSeqNum AND Target.HopCnt is unknownunknown, OR o Target.SeqNum is equal to== OwnSeqNum AND Orig.HopCnt is unknownunknown, OR o Target.SeqNum is equal to== OwnSeqNum AND Target.HopCnt (the last know hop count value) is less than to< Orig.HopCnt (the number of hops traversed by this RREQ to reach the target). In either case (both RREQ and RREP),First, the node MUST addadds the Orig.AddressAddBlk.Target.Address to the add-block andRM. The Target.Address is copied from the Orig.SeqNum toincoming RREQ AddBlk.Orig.Address. Next, the add-tlv- block. It setsnode adds the Orig.AddressAddBlk.Orig.Address to its own address. The Orig.SeqNum isthe node's OwnSeqNum. The node MAY advertise a prefix usingRM and the Prefix add-tlv, as describedAddTLV.Orig.SeqNum (OwnSeqNum) in Section 4.7. Otherwise, the Prefix add-tlv is not included.an address block TLV. The node MAY advertise itOrig.Address is a gateway by using a gateway add-tlv, as described in Section 4.8. Otherwise,copied from the gateway add-tlv is not included. The msg-ttlincoming RREQ AddBlk.Target.Address. Other AddTLVs for the originator and target SHOULD be set to NET_DIAMETER,maximum protocol efficiency, but MAYthey may be set smaller.omitted to reduce message size. The msg-hopcntMsgHdr.HopCnt is set to zero (0). the case of RREQ, the msg-ttl MAY beThe MsgHdr.HopLimit is set in accordance with an expanding ring search as described in to limit the RREQ propagation to a subset of the network and possibly reduce route discovery overhead. 4.3.2. Routing MessageNET_DIAMETER. 5.3.3. RM Processing After general message pre-processing (Section 4.6.2),When a route to the OriginatorRM is then created or updated, as described in Section 4.2.1. If a valid route toreceived the OriginatorMsgHdr.HopLimit is not created or updated then the message MUST be dropped. Each additionaldecremented by one (1) and MsgHdr.HopCnt is incremented by one (1). For each address in the address block(s) SHOULD be processedRM that includes AddTLV-HopCnt information except the Target. For each of thesetarget and those addresses the Node.HopCnt associatedtagged with the addressAddTLV-Ignore, the AddTLV-HopCnt information is incremented by one (1) if it exists and is(1). Next, this node checks whether its routing table has an entry to the AddBlk.Orig.Address using longest-prefix matching [RFC1812]. If a route does not zero, thenexist, the new routing information is considered fresh and a new route table entry is created orand updated as defineddescribed in Section 4.2.1. The updating of the HopCnt occurs after processing. Each address resulting in5.2.2. If a valid routerouting table entry may alleviate a futureexists, the new node's information is compared with the route discovery. Any addressestable entry following the procedure described in Section 5.2.1. If the new node's routing information is considered fresh, 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 further processing of this message is performed. If the originator's routing information was considered fresh, then each address that dois not the target and is not flagged with the Ignore address-block-tlv SHOULD 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 for other locations can eliminate RREQ for those destination, in the event that data needs to be forwarded to these destinations in the near future. For each of these addresses considered, if the routing table does not yieldhave a validmatching route or that areusing longest-prefix matching, then a route is created and updated as described in Section 5.2.2. If a routing 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, the route table entry is updated as described in Section 5.2.2. If the routing information for an Node.Address is not processedconsidered fresh, then if MUST be removed from the RM. Only valid routingRemoving this information ensures that non-fresh information is propagated within RM messages.not propagated. If this node is the Targettarget AND this RM is a RREQ, this node responds with a RREP. The TargetThis node creates a new RREP as described in Section 4.3.1. The Target.Address in the new5.3.2. After processing a RM is setor creating a new RM, a node MAY append additional routing information to the Orig.Address fromRM, according to the RM currently being processed. The Target.HopCnt is the hop count for the Orig.Address. The IPDestinationAddress is set to the Route.NextHopAddress for the Orig.Address of the current RM being processed. The Target.SeqNum is set to Route.SeqNum for Orig.Address from the current RM being processed. Then the new RM undergoes post-processing, according to Section 4.6.4. After processing a RM, a node MAY append its routing information to the RM, according to the process described in Section 4.3.3.process described in Section 5.3.4. The additional routing information will help reduce route discoveries to this node. If all nodes alongat the path append their information path information will also be available.expense of increased message size. If this RM's MsgHdr.HopLimit is greater than one (1), this node is not the Target.Address andtarget, AND this RM is a RREQRREQ, then the current RM (altered by the process defined above) SHOULD be MANETcast.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 Address andtarget, AND this RM is a RREPRREP, then the currentnew RM SHOULD be unicastsent to the next hop address on the route toRoute.NextHopAddress for the Target.RREP's Target.Address. If this node is the Target.Address,target, the current message is processed, but this messageRM's information is not forwarded orretransmitted. 4.3.3. Appending5.3.4. Adding Additional Routing Information to an Existing Routing Messagea RM Appending routing information will alleviate route discovery attempts to this node fromthe nodes whose information is included, if other nodes that process the resultant RM information.use this information to update their routing tables. Nodes MAY append a theirrouting information to a RM processedRM, if theythe node believe that this additional routing information will alleviate future RREQ. This option should be administratively controlled. Prior to appending their own address to a RM, a node MUST increment its OwnSeqNum as defined in Section 126.96.36.199.1.2. Then itthe node appends its IP address (AddBlk-Address) and OwnSeqNum.OwnSeqNum (AddTLV-SeqNum). It MAY also append its Prefix and G-bitother information to its address, such as prefix and/or that it is an Internet Gateway. If included, the RM. ThisNode.HopCnt is set to one (1) if included. Several length fields MUST(1). Routing information about other nodes MAY also be adjusted to include the newly inserted information. 4.4. Route Discovery A node generates a Route Request (RREQ) to discover a route to a particular destination (Target).added. If a sequence numberthis information is known for the Targetincluded, it is placed inmust be flagged with the RREQ. Otherwise, Target.SeqNum assumed to be unknown by processing nodes. A Target.SeqNum of zero (0) MAY be set to indicate that only the destinationAddTLV.AdditionalNode.IsOffPath. Note an address may respond to this RREQ. Ifappear only once in a previous value ofmessage's address blocks. Prior to adding any address, the HopCntmessage is knownsearched for existing entries. If an existing entry exists, this entry will have the Targetinformation as this node's routing table information (created or updated while processing the RM) and therefore no update is necessary. In the event a newly appended address already has an AddTLV-Ignore flag set, it is placedremoved. 5.4. Route Discovery A node creates a RREQ (described in Section 5.3.1) to discover a corresponding add-tlv HopCnt. Otherwise, the HopCnt is not included.route to a particular destination (target). The IPDestinationAddressIP.DestinationAddress for this RREQ is set to the MANETcastAddress.LL_ALL_MANET_ROUTERS. Then the RM is transmitted according to the procedure defined in Section 4.6.5.transmitted. After issuing a RREQ, the originating node waits for a route to be created to the Target.target. If a route is not found within RREQ_WAIT_TIME milliseconds, this node MAY again try to discover a route by issuing another RREQ. To reduce congestion in a network, repeated attempts at route discovery for a particular Targettarget SHOULD utilize a binary exponential backoff. The first time a node issues a RREQ, it waits RREQ_WAIT_TIME milliseconds for a route to the Target.target. 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 SHOULD be buffered. This buffer SHOULD have a fixed limited size and discard older data packets first. If a route discovery has been attempted RREQ_TRIES times without receiving a route to the Target,target, all data packets destined for the corresponding Target SHOULD betarget are dropped from the buffer and a Destination Unreachable ICMP message SHOULD be delivered to the application. 188.8.131.52. Route Maintenance 4.5.1. Active Link Monitoring Before a route canA RERR MUST be used for forwardingissued if a packet,data packet is received and it MUSTcannot be checkeddelivered to make sure that the route is still valid. Ifthe Route.ValidTimeoutnext hop, RERR generation is earlier than the current time, the packet cannotdescribed in Section 5.5.3. A RERR MAY be forwarded,issued immediately after detecting a broken link of an active route to quickly notify nodes that a link break occurred and certain routes are no longer available. If a route has not been used, a RERR message MUSTSHOULD NOT be generated (see section Section 4.5.3). In this case, the Route.DeleteTimeoutunless generation is setexpected to Route.ValidTimeout + ROUTE_DELETE_TIMEOUT. If the current time is after Route.DeleteTimeout, then the route MUST be deleted, though a route MAY be deleted at any time.reduce future traffic. 5.5.1. Active Link Monitoring Nodes MUST monitor links on active routes.routes that are being used. This may be accomplished by one or several mechanisms. Including: o Link layer feedback o Hello messages o NeighborNeighborhood discovery [I-D.ietf-manet-nhdp] o Route timeout o Other monitoring mechanisms or heuristics Upon detecting a link break the detecting node MUST set the Route.ValidTimeout to the current time for all active routes utilizing the broken link. A RERR MUST be issued if a data packet is received and it cannot be delivered to the next hop. RERR generation is described in Section 4.5.3. A RERR MAY be issued after detecting a broken link of an active route to quickly notify nodes that a link break occurred and a route or routes are no longer available. If a route has not been used, a RERR SHOULD NOT be generated unless generation is expected to reduce future control traffic. 184.108.40.206.5.2. Updating Route Lifetimes during Packet Forwarding To avoid route timeouts for active routes, a node MUSTSHOULD update the Route.ValidTimeout tofor the IPSourceAddressIP.SourceAddress to be the current time + ROUTE_TIMEOUTROUTE_VALID_TIMEOUT upon receiving a data packet. This route's Route.Used bit is also set, if implemented. To avoid route timeouts for active routes, a node SHOULD update the Route.ValidTimeout tofor the IPDestinationAddressIP.DestinationAddress to be the current time + ROUTE_TIMEOUTROUTE_VALID_TIMEOUT upon successfully transmitting a packet to the next hop. 4.5.3.This route's Route.Used bit is also set. 5.5.3. Route Error Generation When a data packet is received for a destination without a valid routing table entry, a Route Error (RERR)RERR MUST be generated by this node.generated. When a RREP is being transmitted and no active route to the target exists, a RERR MUST be generated. A RERR informs the sourceIP.SourceAddress that the route does not exist, is no longer available, or is now invalid. In a new RERR, the address of first unreachable node (IPDestinationAddress)(IP.DestinationAddress from the data packetpacket) is inserted. If a value for the unreachable node's SeqNum (AddTLV-SeqNum) is known, it is placed in the RERR; otherwise, if unknown it will be assumed to be zero (0). The msg-ttlSHOULD be set to NET_DIAMETER, but may be set smaller to limit the scope ofplaced in the RERR. The msg-hopcntMsgHdr.HopLimit is set to zero (0).NET_DIAMETER. The IPDestinationAddressMsgHdr.HopCnt is set to the MANETcastAddress. This option will notify the maximum number of nodes of the broken link.one (1). Additional unreachable nodes that required the same unavailable link (routes with the same Route.NextHopAddress and Route.NextHopInterface) MAY be added to the RERR. For each unreachable node the Address is appended.The SeqNum if know shouldSHOULD also be included. Appending additional routingunreachable node information notifies each processing node of additional routes that are no longer available. If SeqNum information is not known or not included all nodes processing the routing information will assume their routing information associated with the unreachable node is no longer valid. The RERR is then processed as described in Section 4.6.5. 4.5.4.sent to the IP.DestinationAddress LL_ALL_MANET_ROUTERS. Sending the RERR to the LL_ALL_MANET_ROUTERS address notifies the maximum number of nodes of the 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 SHOULD setprocesses each unreachable node address. It sets the Route.ValidTimeout to the current time for each Address that meetsfound using longest prefix matching that meet all of the following conditions: 1. The Route.NextHopAddress is the same as the RERR IPSourceAddress.IP.SourceAddress. 2. The Route.NextHopInterface is the same as the interface on which the RERR was received. 3. The Node.SeqNumRoute.SeqNum is zero (0), unknown, OR the result of subtracting Route.SeqNum fromNode.SeqNum is less than or equal tozero using(0), unknown, OR Node.SeqNum - Route.SeqNum <= 0 (using signed 16-bit arithmetic.arithmetic). Each Node.Addressunreachable node that did not result in a change to Route.ValidTimeout SHOULD beis removed from the RERR, since propagation of this information shouldwill not result in any benefit. Prior to post processing a node MAY remove any unreachable node address and its associatedAny information to decreaseassociated with the message size.removed addresses is also removed. If thisno unreachable node addresses remain, no further processing is the Target and the IPDestinationAddress is its own Address then it may stop processing.performed. If this RERR's MsgHdr.HopLimit is greater than one (1) and at least one unreachable node address remains in the RERR, then the RERR it SHOULD be handled as described in Section 4.6.4is sent to continue notification of nodes effected bythe broken link. Otherwise,IP.DestinationAddress LL_ALL_MANET_ROUTERS. Addresses marked with AddTLV-Ignore should remain in the RERR is dropped. 4.6.RERR. 5.6. General DYMO Packet and Message Processing 4.6.1. Packet Processing The length of IP addresses (32-bits for IPv4 and 128-bits for IPv6) inside DYMO messages are dependent on the IP5.6.1. Receiving Packets When a packet header. For example, if the IP header uses IPv6 addresses then all messagesis received, its PktTLV are first examined. Next each message is examined and addresses containedprocessed in the payload use IPv6 addresses. 4.6.2. Generic Message Pre-processingorder. Each message undergoes pre-processing beforemessage's headers are first examined. Next, the MsgTLV are examined. Finally, each message specific processing occurs. During pre-processing, the msg-ttl is decremented by one (1) and the msg-hopcntis incremented by one (1). 4.6.3.processed according to its MsgHdr.type. 5.6.2. Processing Unknown Message and TLV Types We expectTo allow future extensions, DYMO uses bits from the next versionsemantics fields of the generalized MANET packetPktTLV, Message, MsgTLV, and message format  to include messageAddTLV [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 tlv semantic bits to controlcharacteristics for nodes that do not understand the behavior of unknown types. 4.6.4. Generic Message Post-processingtype. Remove If the msg-ttl of any messageSemantics.Remove-bit is zero (0) after processing it MUSTset, this information SHOULD be dropped. 4.6.5. DYMO Control Packet Transmission Packet transmission and re-transmission are controlled byremoved from the IPDestinationAddress.message. Discard If the IPDestinationAddress is a unicast address, the packet IPDestinationAddressSemantics.Discard-bit is replaced by the Route.NextHopAddress from a route table lookup forset, this message SHOULD not be processed further and it should not be propagated. In the Target. If a route forcase of PktTLVs if the TargetSemantics.Discard-bit is unknown or invalidset, no messages from the packet is dropped and a RERR SHOULD be generated. For all currently defined DYMO packets the IPTTL (IPMaxCount) SHOULDshould be set to 1 (IPTTL=1), since all DYMO packet communications are exchanged between direct neighbors only. 4.7. Routing Prefixprocessed or propagated. 5.7. Network Addresses Any node MAY advertise connectivity toa subset of node addresses within itsnetwork address spaceby using a Prefix tlv . The[I-D.ietf-manet-packetbb]. Any nodes (other than the advertising node) within the advertised Prefix SHOULD NOT participate in the MANET and these nodes MUST be reachable by forwarding packets to the node advertising connectivity. For example, 192.168.1.1A.B.C.1 with a prefix length of 1624 indicates all nodes with the prefix 192.168.X.Xmatching A.B.C.X are reachable through 192.168.1.1.the node with address A.B.C.1. The meaning of the Prefix field is altered for routestheroute to thean Internet gateway; Route.IsGatewayRoute.IsInternetGateway is one (1). If the G-bit is set theroute refers to an Internet gateway, its Prefix in association with the IP address indicates that all nodes outside thethat subnet are reachable via the Internet gateway node. For example, a route to a Internet gateway with IP address 192.168.1.1A.B.C.1 and a prefix of 1624 indicates that all nodes with an IP address NOT matching 192.168.X.XA.B.C.X are reachable via this node. 220.127.116.11. 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 Targetstargets outside its configured MANET subnet, as well as delivering packets to destinations outside the MANET. /--------------------------\ / Internet \ \ / \------------+-------------/ MANET Subnet | A.B.C.X +-----+-----+ | MANET | /------| Internet |------\ / | Gateway | \ / | A.B.C.1 | \ | +-----------+ | | MANET | | | | +------------+ | | | MANET Node | | | | A.B.C.2 | | | +------------+ | | +------------+ | | | MANET Node | | | | A.B.C.3 | | \ +------------+ / \ / \-------------------------/ Figure 3: Simple Internet Attachament Example MANET nodes wishing to be reachable from nodes in the Internet MUST have IP addresses within the gateway's configured and advertised MANET subnet. 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 many nodes may commonly wish to communicate with the gateway, the gateway SHOULD indicate to nodes that it is a gateway by using the gateway tlv in any RM created or processed.transmitted. The gatewayInternet Gateway tlv indicates to nodes in the MANET that the Node.Address is attached to the Internet and is capable of routing data packets to all nodes outside of the configured MANET subnet, defined by the Node.Address and Node.Prefix fields. 18.104.22.168. Multiple Interfaces It is likely that DYMO will be used with multiple wireless 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 MANETcastpacket with IP.DestinationAddress set to LL_ALL_MANET_ROUTERS SHOULD send the packet on all interfaces that have been configured for DYMO operation. 22.214.171.124. Packet Generation Limits To avoid congestion, a node SHOULD NOT transmit more than RATE_LIMIT control messages per second. RREQ packets SHOULD be discarded before RREP or RERR packets. 5.6. Configuration Parameters Here are some default parameter values for DYMO:Suggested Parameter Values +------------------------+-------------------------+ | Name Suggested| Value --------------------------- ---------------| +------------------------+-------------------------+ | NET_DIAMETER | 10 | | RATE_LIMIT | 10 ROUTE_TIMEOUT| | ROUTE_VALID_TIMEOUT | 5000 milliseconds | | ROUTE_DELETE_TIMEOUT 5*ROUTE_TIMEOUT RREQ_WAIT_TIME| 5 * ROUTE_VALID_TIMEOUT | | ROUTE_DELETE_PERIOD | 6 * ROUTE_VALID_TIMEOUT | | ROUTE_RREQ_WAIT_TIME | 1000 milliseconds | | RREQ_TRIES | 3 | +------------------------+-------------------------+ Table 1 These suggested values work well for small and medium well connected networks with infrequence topology changes. For largelarger networks or networks with frequent topology changes the default DYMO parameters should be adjusted using either experimentally determined values or dynamic adaptation. For example, in networks with infrequent topology changes ROUTE_TIMEOUTROUTE_VALID_TIMEOUT may be set to a much larger value. It is assumed that all nodes in the network share the same parameter settings. Different parameter values for ROUTE_TIMEOUTROUTE_VALID_TIMEOUT or ROUTE_DELETE_TIMEOUT in addition to arbitrary packet delays may result in frequent route breaks or in extreme cases routing loops. 6.7. IANA Considerations DYMO definesrequires 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. This section also specifies several message-typesmessages types, message tlv- types, and address tlv-types. A new registryFuture types will be created for the values for the various type fields, and theallocated using standard actions as described in [RFC2434]. 7.1. DYMO Message Type Specification The following values will be assigned: msg-type Value -------------------------------- -------address block TLV. DYMO Message Types +------------------------+----------+ | Name | Type | +------------------------+----------+ | Route Request (DYMO-RREQ) 8(RREQ) | 10 - TBD | | Route Reply (DYMO-RREP) 9(RREP) | 11 - TBD | | Route Error (DYMO-RERR)(RERR) | 12 - TBD | +------------------------+----------+ Table 2 7.2. Packet TLV Type Specification Packet TLV Types +-------------------+------+--------+-------------------------------+ | Name | Type | Length | Value | +-------------------+------+--------+-------------------------------+ | Unicast Response | TBD | 10 - | Indicates to the processing | | Request | | TBD address-tlv| 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 this node. | +-------------------+------+--------+-------------------------------+ Table 3 7.3. Address Block TLV Specification Address Block TLV Specification Overview +----------------------+------+--------+----------------------------+ | Name | Type | Length | Value -------------------------------- ----- DYMO SeqNum (multivalue) 20| +----------------------+------+--------+----------------------------+ | DYMOSeqNum | 10 - | 16 | The DYMO sequence num | | | TBD HopCnt (multivalue) 21| bits | associated with this | | | | | address. The sequence | | | | | number may be the last | | | | | known sequence number. | | HopCount | 11 - | 8 bits | The number of hops | | | TBD Prefix (multivalue)| | traversed by the | | | | | information associated | | | | | with this address. | | IsInternetGateway | 12 - | 0 bits | Usde to indicate that this | | | TBD | | node is an Internet | | | | | Gateway (zero length) 22| | IsOriginator | 13 - | 0 bits | Used to indicate that this | | | TBD | | node is the Originator 23 - TBD Target 24of | | | | | the RM. | | IsTarget | 14 - | 0 bits | Used to indicate this node | | | TBD Future values| | is the target of the Type will be allocated using standard actions as described in . For future TypesDYMO | | | | | message | | Ignore | 15 - | 0 | Used to indicate that are unicast hop-by-hop (packetsthis | | | TBD | | addresses should not sent to the MANETcastAddress), these Types MUST include the Target.Address field. 7.be | | | | | processed normally; | | | | | instead it should be | | | | | ignored. | +----------------------+------+--------+----------------------------+ Table 4 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, 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. 8.9. 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,Klein- Berndt, Pedro Ruiz, Fransisco Ros andRos, Koojana KuladinithiKuladinithi, Ramon Caceres, and Thomas Clausen for reviewing of DYMO, as well as several specification suggestions. 9.10. References 126.96.36.199. Normative References [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", RFC 2434,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-demandOn- Demand Distance Vector (AODV) Routing", RFC 3561, July 2003.  Baker, R., "Requirements for IP Version 4 Routers", RFC 1812, June 1995. 188.8.131.52. Informative References [I-D.ietf-manet-nhdp] Clausen, T., Dearlove, C., and J. Dean, "MANET Neighborhood Discovery Protocol", draft-ietf-manet-nhdp-00 (work in progress), June 2006. [I-D.ietf-manet-packetbb] Clausen, T., Dearlove, C., Dean, J., and C. Adjih, "Generalized MANET Packet/Message Format", draft-ietf-manet-packetbb-01 (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.  Johnson, D. and D. Maltz, "Dynamic Source Routing (DSR) in Ad hoc Networks", In Mobile Computing, Chapter 5, pp. 153-181, 1996.  Clausen, T., Dearlove, C., and J. Dean, "Generalized MANET Packet/Message Format", February 2006.Authors' Addresses Ian Chakeres Boeing Phantom Works The Boeing Company P.O. Box 3707 Mailcode 7L-49 Seattle, WA 98124-2207 USA Email: firstname.lastname@example.org Charlie Perkins Nokia Research Center 313 Fairchild Drive Mountain View, CA 94043 USA Phone: +1-650-625-2986 Fax: +1-650-625-2502 Email: email@example.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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