TCP/IP Tutorial and Technical Overview - IBM Redbooks

5.3.6 RIP limitations
There are a number of limitations observed in RIP environments:
► Path cost limits: The resolution to the counting to infinity problem enforces a
maximum cost for a network path. This places an upper limit on the maximum
network diameter. Networks requiring paths greater than 15 hops must use
an alternate routing protocol.
► Network-intensive table updates: Periodic broadcasting of the distance vector
table can result in increased utilization of network resources. This can be a
concern in reduced-capacity segments.
► Relatively slow convergence: RIP, like other distance vector protocols, is
relatively slow to converge. The algorithms rely on timers to initiate routing
table advertisements.
► No support for variable length subnet masking: Route advertisements in a
RIP environment do not include subnet masking information. This makes it
impossible for RIP networks to deploy variable length subnet masks.
5.4 Routing Information Protocol Version 2 (RIP-2)
The IETF recognizes two versions of RIP:
► RIP Version 1 (RIP-1): This protocol is described in RFC 1058.
► RIP Version 2 (RIP-2): RIP-2 is also a distance vector protocol designed for
use within an AS. It was developed to address the limitations observed in
RIP-1. RIP-2 is described in RFC 2453. The standard (STD 56) was
published in late 1994.
In practice, the term RIP refers to RIP-1. Whenever you encounter the term RIP
in TCP/IP literature, it is safe to assume that the reference is to RIP Version 1
unless otherwise stated. This same convention is used in this document.
However, when the two versions are being compared, the term RIP-1 is used to
avoid confusion.
RIP-2 is similar to RIP-1. It was developed to extend RIP-1 functionality in small
networks. RIP-2 provides these additional benefits not available in RIP-1:
► Support for CIDR and VLSM: RIP-2 supports supernetting (that is, CIDR) and
variable-length subnet masking. This support was the major reason the new
standard was developed. This enhancement positions the standard to
accommodate a degree of addressing complexity not supported in RIP-1.
Chapter 5. Routing protocols 189