MPLS-Enabled Applications: Emerging Developments and New Technologies

3.15. STUDY QUESTIONS

1. One of the disadvantages of path protection is the double booking of resources, which is a problem in a situation of resource crunch, such as after one or more failures in the network. One approach to alleviate the double booking problem is to set up the secondary paths without any bandwidth reservations. (a) What is the rationale behind this approach and what mechanisms does it rely on? Another approach is to set up the secondary paths with lower priority than the primary, as explained in Section 3.4. (b) What is the disadvantage in this approach?

2. Look at the protocol extensions described in RFC4090. Pick five of these extensions (new objects or flags in existing objects) and explain the rationale for the extension.

3. Describe why facility protection can lead to longer protection paths than 1:1 protection.

4. Figure 3.8 shows a ring topology where traffic is forced to 'double-back' when taking the protection path. Such scenarios are not limited to ring topologies alone. Can you give another example of a topology where the same might happen?

5. A particular network is made up of OC48/STM16 and OC192/STM64 links and has two classes of LSPs: high-priority and low-priority ones (in this context, priority does not necessarily refer to the setup/hold priority). High-priority LSPs are signaled over OC192/STM64 links only, while low-priority LSPs are signaled over OC48/STM16 links. The operator would like to implement facility-based link protection, while at the same time requiring ...