On state-independent and state-dependent path restoration in self-healing networks

We first present a heuristic algorithm which is based on the minimum cost route concept for capacity allocation and flow assignment in self-healing networks, and show via numerical examples that it can yield near-optimal solutions for both spare and joint optimization. Based on the near-optimal solutions, we then compare two important path restoration schemes applicable in ATM VP networks, named state-independent (SI) and state-dependent (SD) schemes, in terms of spare capacity requirement (SCR), restoration speed, VPI redundancy and node storage capacity. The comparison is based on the common single link failure scenario and 100% restoration. It is found that SI scheme has advantages over the SD scheme if their difference in SCR is small. However, if the difference cannot be ignored and there is no shortage in VPI resources the SD scheme may be a good candidate. Further, fast restoration can be achieved by using bidirectional or group VP restoration.