network protocols handbook.pdf

76Protocols GuideTCP/IP - Network Layer ProtocolsProtocol NameRIPng: Routing InformationProtocol next generation forIPv6Protocol DescriptionRIPng, an information routing protocol for the IPv6, is basedon protocols and algorithms used extensively in the IPv4 Internet.In an international network, such as the Internet, there aremany routing protocols used for the entire network. The networkwill be organized as a collection of Autonomous Systems (AS).Each AS will have its own routing technology, which may differamong AS’s. The routing protocol used within an AS is referredto as an Interior Gateway Protocol (IGP). A separate protocol,called an Exterior Gateway Protocol (EGP), is used to transferrouting information among the AS’s. RIPng was designed towork as an IGP in moderate-size AS’s. It is not intended for usein more complex environments.RIPng is one of a class of algorithms known as Distance Vectoralgorithms. The basic algorithms used by this protocol wereused in computer routing as early as 1969 in the ARPANET.However, the specific ancestry of this protocol is within the Xeroxnetwork protocols. The PUP protocols used the Gateway InformationProtocol to exchange routing information. A somewhatupdated version of this protocol was adopted for the Xerox NetworkSystems (XNS) architecture, with the name Routing InformationProtocol (RIP). Berkeley’s routed is largely the same asthe Routing Information Protocol, with XNS addresses replacedby a more general address format capable of handling IPv4 andother types of address, and with routing updates limited to oneevery 30 seconds. Because of this similarity, the term RoutingInformation Protocol (or just RIP) is used to refer to both theXNS protocol and the protocol used by routed.For the IPv4 network, the routing information protocols are RIPand RIP2 - click for details. In the document, only the details ofRIPng will be described.Protocol StructureCommand (1 byte) Version (1 byte) 0 (2 bytes)Route table entry 1 (20 bytes). .Route table entry N (20 bytes)• Route table entry -- Each route table entry contains adestination prefix, the number of significant bits in theprefix and the cost of reaching that destination.Related protocolsRIP, RIP2, IP, UDP, TCP, EGP, IGPSponsor SourceRIPng is defined by IETF (http://www.ietf.org) RFC2080.Referencehttp://www.javvin.com/protocol/rfc2080.pdfRIPng for IPv6• Command -- Two commands are:Request A request for the responding systemto send all or part of its routing tableResponse A message containing all or part ofthe sender’s routing table.• Version -- The version of the protocol. The currentversion is version 1.