Survivability schemes for metro ethernet networks

Abstract

Ethernet is becoming a preferred technology to be extended to Metro Area Networks (MANs) due to its low cost, simplicity and ubiquity. However, the traditional spanning tree based Ethernet protocol does not meet the requirements for MANs in terms of fast recovery and guaranteed protection.

In this study, we firstly propose and discuss a local restoration mechanism for Metro Ethernet networks using multiple spanning trees, which is distributed, fast, and does not need failure notification. A fast spanning tree reconnection (FSTR) mechanism which has lower implementation cost to handle single link failure is then proposed. Under FSTR mechanism, a distributed failure recovery protocol is activated to reconnect the broken spanning tree using a reconnect-link not on the original spanning tree. We further improve the FSTR mechanism by a novel approach to handle double-link failures. Finally, a two-layer architecture for survivability in Ethernet over WDM networks is presented.

We develop integer linear programming models (ILP) to formulate each proposed survivability schemes. We theoretically prove that the pre-configuration problem of local restoration and FSTR schemes are NP-Complete. We develop several efficient algorithms, including two heuristics for local restoration mechanism and an augmentation based algorithm for FSTR mechanism. We demonstrate the effectiveness of the proposed survivability schemes through numerical results obtained from solving ILP models and simulation results on various network topologies and scenarios.