On improving the efficiency and manageability of NotVia
This paper presents techniques that improve the efficiency and manageability of an IP Fast Reroute (IPFRR) technology: NotVia. NotVia provides the IPFRR service for all destinations in an ISP's network upon any single link or node failure, while previous proposals such as Loop-free Alternates (LFA) can not guarantee this level of coverage. However, NotVia increases the computational and memory costs of the IPFRR service, and poses new challenges to network management, as routers are unaware of the links and nodes (hence the amount of traffic) that they actually protect. This paper introduces three techniques: NotVia aggregation, prioritized NotVia computation, and the rNotVia algorithm that collectively reduce the overhead of NotVia and improve its manageability. We use simulations to evaluate these techniques on real ISP topologies as well as on randomly generated topologies. The results show that the computational and memory overhead of NotVia are reduced to a fraction of their previous values on various topologies, suggesting that the techniques proposed in this paper make NotVia a more efficient and easy-to-manage IPFRR solution. Copyright 2007 ACM.