Unicast IP Routing

Troubleshooting RIP for IP

If a RIP environment is properly configured, RIP routers learn all the best routes from neighboring routers after convergence. The exact list of routes added by RIP to the IP routing table depends, among other factors, on whether or not the router interfaces are inside a subnetted region, whether or not RIP v2 is being used, and whether or not host routes or default routes are being advertised.

Problems with RIP can occur in a mixed RIP v1 and v2 environment, with the use of Silent RIP hosts, or when all the appropriate RIP routes are not being received and added to the IP routing table.

Improper routes in a mixed RIP v1 and RIP v2 environment

On networks containing RIP v1 routers, verify that RIP v2 is configured to broadcast its announcements on networks containing RIP v1 routers.

On networks containing RIP v1 routers, verify that the RIP v2 router interfaces are configured to accept both RIP v1 and RIP v2 announcements.

Silent RIP hosts are not receiving routes

If there are Silent RIP hosts on a network that are not receiving routes from the local RIP router, verify the version of RIP supported by the Silent RIP hosts. For example, if the Silent RIP hosts only support listening for broadcasted, RIP v1 announcements, you cannot use RIP v2 multicasting.

If you are using the RIP listener component available on Microsoft® Windows NT® Workstation version 4.0, Service Pack 4 and later, you must configure your RIP routers for RIP v1 or RIP v2 broadcasting.

RIP routers are not receiving expected routes

Verify that you are not deploying variable length subnetting, disjointed subnets, or supernetting in a RIP v1 or mixed RIP v1 and RIP v2 environment.
If authentication is enabled, verify that all interfaces on the same network are using the same case-sensitive password.
If RIP peer filtering is being used, verify that the correct IP addresses for the neighboring peer RIP routers are configured.
If RIP route filtering is being used, verify that the ranges of network IDs for your internetwork are included or are not being excluded.
If RIP neighbors are configured, verify that the correct IP addresses are configured for the unicasted RIP announcements.
Verify that IP packet filtering is not preventing the receiving (through input filters) or sending (through output filters) of RIP announcements on the router interfaces enabled for RIP. RIP traffic uses UDP port 520.
Verify that TCP/IP filtering on the router interfaces is not preventing the receiving of RIP traffic.
For dial-up demand-dial interfaces using auto-static updates, configure the demand-dial interfaces to use RIP v2 multicast announcements. When a router calls another router, each router receives an IP address from the other router's IP address pool, which are on different subnets. Because broadcasted RIP announcements are addressed to the subnet broadcast address, each router does not process the other router's broadcasted request for routes. Using multicasting, RIP requests and announcements are processed regardless of the subnet for the router interfaces. For more information about demand-dial interfaces and auto-static updates, see "Demand-Dial Routing" in this book.
For RIP over demand-dial interfaces, verify that the packet filters on the remote access policy profile of the answering router are not preventing the receipt or sending of RIP traffic. TCP/IP packet filters can be configured on the profile properties of the remote access policies on the answering router (or the Internet Authentication Service (IAS) server if RADIUS is used) that are used to define the traffic that is allowed on the remote access connection.

Host or default routes are not being propagated

By default, host routes and default routes are not announced using RIP. You can change this behavior from the Advanced tab of the properties of a RIP interface in the Routing and Remote Access snap-in.