CHAPTER 14 IGPs: RIP, OSPF, and IS­IS 355 ROUTING INFORMATION PROTOCOL The RIP is still used on all types of TCP/IP networks. The basics of RIP were spelled out in RFC 1058 from 1988, but this is misleading. RIP was in use long before 1988, but no one bothered to document RIP in detail. RIP is bundled with almost all implementa- tions of TCP/IP, so networks often run only RIP. Why pay for something when RIP was available for free? RIP version 1 (RIPv1) in RFC 1058 has a number of annoying limitations, but RIP is so popular that doing away with RIP is not a realistic consideration. RFC 1388 intro- duced RIP version 2 (RIPv2 or sometimes RIP-2) in 1993. RIPv2 addressed RIPv1 limita- tions, but could not turn a distance-vector protocol into a link-state routing protocol such as OSPF and IS­IS. RIPv2 is backward compatible with RIPv1, and most RIP implementations run RIPv2 by default and allow RIPv1 to be configured. In this chapter, the term "RIP" by itself means "a version of RIP runs RIPv2 by default but can also be configured as RIPv1 as required." Router vendor Cisco was deeply dissatisfied with RIPv1 limitations and so created its own vendor-specific (proprietary) version of an IGP routing protocol, which Cisco