Chapter 7. Routing Information Protocol Version 2

• Operation of RIPv2

  RIPv2 Message Format

  Compatibility with RIPv2

  Classless Route Lookups

  Classless Routing Protocols

  Variable-Length Subnet Masking

  Authentication

• Configuring RIPv2

  Case Study: A Basic RIPv2 Configuration

  Case Study: Using VLSM

  Case Study: Discontiguous Subnets and Classless Routing

  Case Study: Authentication

• Troubleshooting RIPv2

  Case Study: Misconfigured VLSM

RIPv2 is defined in RFC 1723 ^[1] and is supported in IOS versions 11.1 and later. RIPv2 is not a new protocol; rather, it is RIPv1 with some extensions to bring it more up-to-date with modern routing environments. These extensions are:

^[1] Supplemental to this RFC are RFC 1721, "RIP Version 2 Protocol Analysis," and RFC 1722, "RIP Version 2 Protocol Applicability Statement."

• Subnet masks carried with each route entry

• Authentication of routing updates

• Next-hop addresses carried with each route entry

• External route tags

• Multicast route updates

The most important of these extensions is the addition of a Subnet Mask field to the routing update entries, enabling the use of variable-length subnet masks and qualifying RIPv2 as a classless routing protocol.

RIPv2 is the first of the classless routing protocols discussed in this book. As such, this chapter serves as an introduction to classless routing, as well as to RIPv2.