Providing ATM multipoint survivability via disjoint VC mesh backup groups

This paper presents simulation experiments investigating the feasibility and cost of providing survivability to ATM multipoint groups using dedicated bandwidth on disjoint backup groups. Disjoint dedicated backup groups are formed via the VC mesh model by two different approaches. (1) a backup group consisting exclusively of point-to-point circuits (unicast), or (2) a backup group consisting exclusively of point-to-multipoint circuits (multicast). Results for the two networks studied show that although backup groups of point-to-multipoint circuits (multicast) are lower in cost than backup groups of point-to-point circuits (unicast) at a 95% confidence level, the feasibility of providing guaranteed survivability with back-up groups via either approach begins at only about 50% for a group size of three and decreases rapidly for larger group sizes due to multipoint “trap” topologies and hop-limit constraints. The conclusion is that, while use of disjoint dedicated back-up groups for ATM multipoint may be viable in certain dense networks with rich connectivity based on the two networks studied neither approach provides acceptable survivability guarantees for arbitrary networks especially noting that network congestion is not considered