RIP Version 2 Does Not Advertise Subnet Routes

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The feature described above, subnet hiding, is expected behavior with RIP version 1. RIP version 1 does not have a field for the subnet mask of a network and does not support subnet advertisements. When advertising routes to an external network that could not possibly know the subnet mask, the subnetted routes are reduced to a single network route or a Summary Route.

RIP version 2 is capable of advertising subnet masks; however, RIP version 2 may not advertise specific subnet routes when RIP version 1 routers could mistake the routes as host routes. This would be the case if the RIP version 1 router had a different network ID than the RIP version 2 router.

This behavior of subnet hiding is always done with RIP version 1 and is usually done with RIP version 2. With some implementations of RIP version 2, subnet hiding can be enabled or disabled.

If the announce mode is set to RIP1 or RIPv2 broadcast the subnet summarization (hiding) is always performed. You must choose RIPv2 multicast mode to disable subnet summarization.

Also, the RRAS command-line utility can be used to turn this feature on or off. The following syntax example is provided:

routemon ip set protocol
[proto=] rip
[name=] <interface-name>
[subnetsummary=] <enable|disable>]