HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual page 628

IP Routing—Configuring RIP, OSPF, BGP, and PBR
Configuring RIP
13-14
an address family field—set at 2, indicating that addresses are in IPv4
format
up to 25 entries, each consisting of:
• a destination IP address
• a metric, which is the number of hops to the destination address from
the router that is sending the packet
When a router discovers a new or better route from a RIP v1 update, it assumes
that the neighbor from which it received the update is the next hop for the
route. The router adds one to the metric for its own routing table entry.
RIP v2 fixes several shortcomings of RIP v1. RIP v2 provides route summari-
zation for classful networks and supports EGPs. A RIP v2 packet includes:
a command field—indicating whether the packet is a request or a reply
a version field
a routing domain—identifying the routing daemon that produced the
message, which allows a device to run several RIP processes at once
an address family field
a route tag (which includes the AS number for use with EGPs)
up to 25 entries, each consisting of:
• a destination IP address
• a subnet mask—providing support for variable-length subnets
• a next-hop IP address
• a metric—the number of hops to the destination address from the
next-hop address
When a router discovers a new or better route to a destination from a RIP v2
packet, it enters the route with the next-hop IP address specified in the packet.
If the next-hop IP address field is all zeros, the router assumes that the source
of the packet is the next-hop IP address. (This assumption provides some
backward compatibility with RIP v1).
RIP v1 interfaces broadcast their routing updates to the entire subnet. RIP v2
routers join the group for the RIP v2 multicast address (224.0.0.9) and multi-
cast updates to this address. Therefore, RIP v1 and v2 interfaces may not
receive each other's updates. You must take care to configure the router to
send and listen for the correct version of RIP.