VRRP: Increasing Reliability and Failover with the Virtual Router Redundance Protocol

5.4. VRRP over Token Ring

Token Ring has several characteristics that make running VRRP over it difficult.

5.4.1. The Token Ring Problem

Chiefly, there is no generally available multicast mechanism available over old and new implementations of Token Ring. The newer implementations of Token Ring do support multicasting using group addresses, but Token Ring functional address support is the only generally available multicast mechanism for Token Ring. Also, only a limited number of functional addresses are available, and these could collide with use of the same functional address for another purpose.

There are 31 Token Ring functional addresses, each 48 bits long, organized into 17 bits of constant followed by 31 bits, with only 1 bit on to denote ...