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.
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 |
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