RIPv2 Next Hop Address

Remember on the RIPv2 PowerPoint slide (as shown) we were seeing on the debug ip rip a 0.0.0.0 address and couldn't explain why. Steven Zinkie jumped right in on this and reported back with the answer. He found the following explaination in our book..

1) Like RIPv1, RIPv2 is encapsulated in a User Datagram Protocol (UDP) segment using port 520 and can carry 25 routes per update.

2) The first significant extension in the RIPv2 message format is the subnet mask field (32 bit mask) to be included in the RIP route entry.

3) The second significant extension of RIPv2 is the addition of the next-hop address. The next-hop address is used to identify a better next-hop address – if one exists. If the field is set to 0.0.0.0, the address of the sending router is the best next-hop address.

Thanks Steven - mystery solved!