On shared risk link group optimization [Invited]

Shared risk link groups (SRLGs) have been defined and implemented in many network planning tools and routing protocols. A single SRLG represents one potential failure, and a large service provider´s network could easily contain tens of thousands of potential failures. The greater the number of SRLGs, the more difficult it is to attain good performance from planning tools (like routers) whose computations are dependent on the number of SRLGs. For many routing protocols using SRLG information, the situation becomes even worse, because a routing protocol may have space constraints to hold a limited number of SRLGs. These issues create a challenge to optimize the SRLG calculations such that the SRLG-related functions are not impacted or the impacts on the SRLG-related functions are limited. This paper takes a closer look at the SRLG optimization issue and identifies the facts/observations of SRLGs. Then we propose algorithms for how to reduce the number of SRLGs for different applications based on our observations.