System for Improving the Re-Healing of Partitioned Clusters in Hierarchical Networks
Original Publication Date: 2001-Oct-13
Included in the Prior Art Database: 2003-Jun-20
Problem Statement In link state routing protocols like OSPF and PNNI, the resolution of links state element conflicts during database synchronization is undesirable. It can dramatically increase the amount of routing information exchange at a time when it is already at a peak. This is particularly so in environments where conflicts are most likely occur due to the topology not being stable, namely wireless mobile networks. Wireless networks are bandwidth constrained and are easily overloaded by surges of protocol activity. Such surges can result in extended network convergence times and in extreme cases cause the protocol to thrash, thus preventing convergence completely. Consider the example of a PNNI network that uses configured clustering (peer groups), where each cluster elects a representative from its members (Peer Group Leader) to represent it at higher levels of a hierarchy (Logical Group Node). 1. The cluster is partitioned due to the failure or removal of a link. 2. Each partition of the original cluster initiates a new election and elects a representative 3. The peer group leaders in each partition generate link state elements to summarize the peer groups partitions that they represent 4. The partition is healed when a link between them is reestablished The normal chain of events on the link being reestablished is to initially exchange databases. After databases have been exchanged and a new peer group leader selected, the node which looses the election must flush the link state elements that it created at higher levels.