Chapter 7. Protection and Restoration
This chapter covers the following topics:
Networks fail. More precisely, pieces of networks fail. Lots of things can cause something to fail in a network. They run the gamut from loosely connected cables to fiber cuts. Router crashes are another form of failure.
From a router's perspective, there are two kinds of failures in a network—link failures and node failures. It doesn't matter what the underlying cause is. A link failure can be a fiber cut, an ADM problem, or any number of other things. A node failure can be anything from a power problem to a router crash to a router being taken down for scheduled maintenance. No matter what the cause, all failures are either a link failure or a node failure.
It is highly desirable to reduce the negative effects of such failures, such as packet loss. As it turns out, MPLS TE and its ability to steer traffic away from the IGP-derived shortest path helps mitigate packet loss associated with link or node failures in the network. MPLS TE's ability to do this is known as Fast Reroute (FRR) or simply MPLS TE Protection.
This chapter covers the aspects of MPLS TE that deal with fast recovery from failures—what they are, how they work, and how you can configure them using Cisco IOS Software.