Appendix C. RIP Version 2 (RIPv2)

This appendix covers the following topics:

• RIPv2 Authentication

• RIPv2 Subnet Mask Support

• RIPv2 Next Hop Identification

• RIPv2 Multicasting

• RIPv2 Concerns

RIPv2 is an improvement over RIP in that RIPv2 is ideal for small internetworks. RIPv2 is ideal because it optimizes IP Address assignments, minimizing the wasted IP Address spaces. This optimization is accomplished through the use of Variable-Length Subnet Masks (VLSMs) for network addresses, enabling a Classless Interdomain Routing (CIDR) addressing scheme.

RIPv2 provides for more efficient use of IP address space with support for VLSM, CIDR, and subnets (small networks that are part of a larger network). RIPV2 also enables authentication methods, such as MD5 and plain text, and improved support over RIP for routing updates. RIPv2 multicasts (updates sent to RIPv2 routers) rather than broadcasting (updates sent to all routers, RIPv2 and non-RIPv2) are used for advertising routing updates.

RIPv2 was created in January 1993 and is backward compatible with RIPv1. RIPv2 added the following features not supported in RIP:

• RIPv2 authentication

• Subnet mask support (CIDR)

• Next hop IP addresses

• RIPv2 message multicasting