Both protection and restoration are fundamental consideration in designing robust optical networks, especially in challenging GMPLS/ASON architecture. Fast Rerouting technology as one important method of MPLS-Traffic Engineering is an efficient and powerful technology for protecting MPLS-TE LSPs from link and node failures. By supporting locally reparation of the affected LSPs at the point of failure, link and node protection are achieved quickly. The goal of real-time IP applications over native IP unicast/multicast networks or LDP based MPLS networks is to limit the IP packet loss duration in the network to 10s of milliseconds in the event of linkode failures. RSVP signaled LSP is used with explicitly routed path as the re-direct tunnel, while the protected traffic can be either MPLS traffic engineered LSPs, LDP based LSPs, IP unicast, IP multicast traffic or the mix of them. This mechanism can be applied to both point-to-point links and multi-access links in the cases of the link protection and node protection. Besides the above resilience research on IP/MPLS single layer, tests or experiments on multilayer mechanism, i.e. optical and IP/MPLS network layer composing of multi-vendor routers and multi-domain, are carried out by a number of famous organizations and companies where optical dedicated/shared mesh protection/restoration and MPLS fast rerouting survivable techniques are combined to guard against both dual link failures and combined link and IP/MPLS hardware and software router failures. Those techniques used in next-generation backbone network design result in that not only familiar failures such as fiber cuts or amplifier damage but also system failures such as router failures or multiple concurrent failures can be recovered fast and effectively at corresponding layer. In this paper, on the basis of analysis of EETF's internet drafts about fast rerouting algorithm and standards in MPLS-TE and GMPLS, new fast rerouting algorithm and corresponding simulation results are proposed step by step. At the same time, resilient performance in a GMPLS/ASON design especially under mesh optical protection is studied carefully while a few coming function requirements in OXC and router equipments obtained from the above analysis are discussed to some extent. Figures and tables are presented for explaining the enhanced fast rerouting technology reducing confusion of packets and achieving falling delay time of rerouting. Finally, some issues for further work are to identify the importance where to place appropriate resilient mechanism in the next network design.
展开▼
