RIP

RIP

  • UDP port 520 is used for transport.
  • RIPv2 uses 224.0.0.9 for multicast
  • Update interval is 30 seconds.
  • RIP v2 allows RIP to tag routes as they are distributed into RIP.
  • Next Hop fields: supports the assignment of a next hop IP address for a route.
  • RIP adds 1 to the route before sending the update. So if it has a route of 2, when it updates other router, it advertises the hop count as 3.
  • ip maximum-paths” command under router rip to change default. 4 equal-metric routes
  • Split Horizon: instead of advertising all routes a particular interface, RIP omits the routes whose outgoing interface filed matches the interface out which the update would be sent. It’s on by default except for cases in which FR is configured with the IP address on a physical interface.
  • Route Poisoning and Poison Reverse: route poisoning is when a hop count of 16 is advertised and Poison reverse is advertising 16 but in reaction to an update received on that same interface.
  • Holddown and invalid timer: 180 seconds, Flush Timer: 240 seconds.
  • RIP has triggered updates and can converge to an alternate route in typically less than a minute.
  • Passive Interface: in router rip, use passive-interface <type> <number>
  • clear ip route * command bypasses loop prevention features so it can be risky.
  • network command must have classful network as the parameter
    • Sending RIP updates: can be disabled by passive interface
    • Listening to RIP updates: can be filtered (incoming routes) using distribute list
    • advertising the connected subnet: filter outbound advertisements on other interfaces using distribute lists.
  • on multicaccess networks, you can use neighbor ip-address RIP subcommand.
  • to filter routes, use distribute list, can use ACL or prefix-list. If no interface specified, applied to all routes coming in!

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