3Com Switch 8800 Advanced Software V5 Configuration Guide

RIP Overview 273
n
RFC 1723 only defines plain text authentication. For information about MD5
authentication, refer to
“Configuring RIP-2 Message Authentication” on page 281.
TRIP Triggered RIP (TRIP), a RIP extension on WAN, is mainly used in dial-up network.
Working mechanism
Routing information is sent in triggered updates rather than periodic broadcasts to
reduce the routing management cost the WAN.
■ Only when data in the routing table changes or the next hop is unreachable, a
routing update message is sent.
■ Since the periodic update delivery is canceled, an acknowledgement and
retransmission mechanism is required to guarantee successful updates
transmission on WAN.
Message types
RIP use three new types of message which are identified by the value of the
Command filed.
■ Update Request (type value 9): Requests needed routes from the peer.
■ Update Response (type value 10): Contains the routes requested by the peer.
■ Update Acknowledge (type value 11): Acknowledges received Update
Response messages.
TRIP retransmission mechanism
■ If receiving no Update Responses after sending an Update Request, a router
sends the request again after a specified interval. If still receiving no Update
Response after the upper limit for sending requests is reached, the router
considers the neighbor unreachable.
■ If receiving no Update Acknowledge after sending an Update Response, a
router sends the Update Response again after a specified interval. If still
receiving no Update Acknowledge after the upper limit for sending Update
Responses is reached, the router considers the neighbor unreachable.
RIP Features Supported The current implementation supports the following RIP features.
■ RIP-1 and RIP-2
■ RIP Multi-instance. This means that RIP can serve as an internal VPN routing
protocol, running between CE and PE on the BGP/MPLS VPN network.
■ TRIP
Protocols and Standards RFC 1058: Routing Information Protocol
RFC 1723: RIP Version 2 - Carrying Additional Information
RFC 1721: RIP Version 2 Protocol Analysis
RFC 1722: RIP Version 2 Protocol Applicability Statement
RFC 1724: RIP Version 2 MIB Extension