RIP CheatSheet

RIPv1

• distance vector protocol
• UDP port 520
• no support for VLSM or CIDR (no custom set subnets)
• metric is router hop count.  max count is 15.  unreachable is 16
• updates broadcast full update every 30 seconds, accept with serial link which is full update initially, than silent until update occurs.
• split horizon (don't advertise route back to interface it was learned from) with poison reverse (advertise route with infinite distance back on interface learned from)
• no authentication
• (Cisco) typical update timer = 30 seconds, (Cisco) typical invalid timer is 180 seconds
• Regular updates can cause simultaneous update / jitter issues.  RIP_JITTER variable added to time sent out (0-15%).
• uses variant of Bellman-Ford Algorithm

Timers

• Invalid timer - if update not received for 180 seconds - route goes to 16 (infinity)
• Flush timer - if upate not recieved for 240 seconds, route is flushed.
• Holddown timer - 180 seconds to deal with flapping

Timer Comparison

Cisco Config lines

RIPv2

• distance vector protocol
• UDP port 520
• CIDR and VLSM supported.  subnet mask included in route entry
• metric is router hop count.  max count is 15.  unreachable is 16
• updates via multicast every 30 seconds (to 224.0.0.9).
• supports authentication (PAP and CHAP)
• split horizon with poison reverse
• remember no auto-summary - otherwise will summarize on classful boundaries
• able to do load balancing - default 4 equal cost paths - can force to 6 with maximum-paths <# of paths> 
• supports manual route/supernet summarizing

Cisco Config lines