RIP notes

• RIP uses multicast address 224.0.0.9 UDP 520
• It supports authentication by using a key chain
• White space is a valid character in the key string. Always verify correct key string using "show key chain"
• You can conditionally advertise a default route over a specific interface using default-information originate. You create a route-map that matches the prefix that requires monitoring and sets the interface over which the default route will be advertised
• It's not required to have a default route in order to advertise it in RIP
• By default RIP performs source validation on updates it receives. The update source must be in the same subnet, otherwise it's ignored. You can use "no validate update-source" to change that behavior.
• An interface with RIP enabled and configured with IP un-numbered doesn't perform source validation .
• RIP doesn't suppress multicasts on an interface, although the neighbor command for static neighborship may be active. You need to make interface passive to stop sending multicasts.