network protocols handbook.pdf

322Protocols GuideOther ProtocolsProtocol NameToshiba FANP: Flow AttributeNotification ProtocolProtocol DescriptionFlow Attribute Notification Protocol(FANP) is a protocol betweenneighbor modes which manages cut-through packet forwardingfunctionalities. In cut-through packet forwarding, a routerdoesn’t perform conventional IP packet processing for receivedpackets. FANP indicates mapping information between a datalinkconnection and a packet flow to the neighbor node. It helpsa pair of nodes manage mapping information. By using FANP,routers such as the CSR (Cell Switch Router) can forward incomingpackets based on their datalink-level connection identifiers,bypassing usual IP packet processing. FANP has the followingcharacteristics:• Soft-state, cut-through path (Dedicated-VC) management• Protocol between neighbor nodes instead of end-toend• Applicable to any connection-oriented, datalink platform.FANP generally runs on ATM networks.There are 7 FANP control messages. They are encapsulatedinto IP packets, apart from the PROPOSE message which usesan extended ATM ARP message format. The destination IP addressin the IP packet header signifies the neighbor node’s IPaddress. The source IP address is the sender’s IP address. TheIP protocol ID is 110.The following message format exists for: Offer, Ready and Errormessages. Propose Ack, Remove and Remove Ack messagesdo not have the flow ID field.Protocol Structure8 16 24 32bitVersion OpCode ChecksumVCID type Flow ID Reserved/Refresh int./Error codeVCIDFlow IDThe VCID uniquely identifies the datalink connectionbetween neighbor nodes.• Flow ID - If the Flow ID is 0, then the flow ID fieldis null. If the Flow ID is 1, then the Flow ID field describedbelow is present.• Reserved - In Offer messages the Refresh Timer fieldappears here. In error messages, the Error code fieldappears here.• Refresh timer - The interval of the Refresh timer, inseconds. (Only appears in Offer messages.) The recommendedvalue is 120.• Error code - Only appears in Error Messages.• VCID - Virtual Connection Identification.• Flow ID - The Flow ID field does not appear in proposeACK, Remove and Remove Ack messages.When there is a flow ID type value of 1, this field containsthe source and destination IP addresses of theflow.Sponsor SourceFANP is a Toshiba protocol circulated by IETF (www.ietf.org) inRFC 2129.Referencehttp://www.javvin.com/protocol/rfc2129.pdfToshiba’s Flow Attribute Notification Protocol (FANP) Specification• Version - The Version number. This version is version1.• OpCode – Operation code, the following OpCodevalues exist: 1 Propose Ack; 2 Offer; 3 Ready;4 Error; 5 Remove; 6 Remove ACK.• Checksum - A 16 bit checksum for the whole message.• VCID type - The type of VCID. The current value is 1.