Cisco CCNA

Routing Protocols and Classless Addressing

Having waded through all the theory and binary, consider routing protocols for a moment. To reap the benefits of classless addressing (such as supernetting), you must use a routing protocol that supports classless addressing—perhaps OSPF, EIGRP, or Border Gateway Protocol (BGP). These classless protocols carry both network prefixes and their corresponding prefix masks in routing updates.

RIP and 1GRP, on the other hand, do not support classless addressing. RIP and 1GRP also do not support variable length masks within a major net, because they do not carry mask information in routing updates as classful routing protocols do. Instead, RIP andJGRP assume there is a fixed subnet mask per major net, and that mask is determined from the mask that was configured on the interface?

NOTE

RIPv2, version 2 of RIP. supports VLSM but is less widely used than OSPF and LIGRP.