MPLS-Enabled Applications: Emerging Developments and New Technologies

5.5. COMPARISON OF THE LSP SETUP METHODS

The LSP setup method is one of the important decisions in an interdomain deployment and like any other design choice it involves tradeoffs. For example, contiguous LSPs are more intuitive but they have less desirable scaling properties when compared to nested or stitched ones. The question is not which LSP setup method is better, but rather which one is better for a particular deployment. For example, the fact that a stitched LSP can be reoptimized locally is not an advantage in a setup where reoptimization will never be run. Table 5.1 presents a summary comparison of the different setup methods.

Table 5.1. Comparison of the different LSP setup methods

	Contiguous	Stitching	Nesting
Number of LSPs in the transit domain, assuming N LSPs in the head end domain	N	N	Smaller than N, depends on the number of FA LSPs
Support of per-domain path computation	Yes	Yes	Yes
Requires protocol extensions	Yes	Yes	Yes
Reoptimization in the transit domain affects other domains	Yes	No	No
Control over reoptimization	Head end	Local (head end if desired)	Local (head end if desired)
MP when protecting a boundary entry node	Any node in the path	TE LSP segment endpoint	FA LSP endpoint