31 Days Before Your CCNA Exam

208 31 Days Before Your CCNA ExamFigure 14-8RIPv1 and RIPv2 Message FormatsRIPv1Bit07 8 15 16 23 24 31Command = 1 or 2 Version = 1Must Be ZeroAddress Family Identifier (2 = IP)Must Be ZeroIP Address (Network Address)RouteEntryMust Be ZeroMust Be ZeroMetric (Hops)Multiple Route Entries, Up to a Maximum of 25RIPv2Bit07 8 15 16 23 24 31Command = 1 or 2 Version = 2Must Be ZeroAddress Family Identifier (2 = IP)Route TagIP Address (Network Address)RouteEntrySubnet MaskNext HopMetric (Hops)Multiple Route Entries, Up to a Maximum of 25With this configuration, R2 will now send and receive only RIPv2 messages. That means we must configureR1 with the version 2 command as well because R2 will ignore the RIPv1 messages sent by R1.Disabling AutosummarizationNotice the line in the show ip protocols output from Example 14-18 that states:Automatic network summarization is in effectBy default, RIPv2 automatically summarizes networks to the classful boundary just like RIPv1. So,to support discontiguous subnets and VLSM, you must first disable automatic summarization withthe no auto-summary command on all RIPv2 routers to ensure that individual subnets are sent inrouting updates—not the classful network address.RIPv2 Verification and TroubleshootingThere are several ways to verify and troubleshoot RIPv2. You can use many of the same commands forRIPv2 to verify and troubleshoot other routing protocols. It is always best to begin with the basics: