nanog mailing list archives
Re: Devil's Advocate - Segment Routing, Why?
From: Mark Tinka <mark.tinka () seacom mu>
Date: Sun, 21 Jun 2020 18:00:12 +0200
On 21/Jun/20 15:48, Robert Raszuk wrote:
Actually when IGP changes LSPs are not recomputed with LDP or SR-MPLS (when used without TE :). "LSP" term is perhaps what drives your confusion --- in LDP MPLS there is no "Path" - in spite of the acronym (Labeled Switch *Path*). Labels are locally significant and swapped at each LSR - resulting essentially with a bunch of one hop crossconnects. In other words MPLS LDP strictly follows IGP SPT at each LSR hop.
Yep, which is what I tried to explain as well. With LDP, MPLS-enabled hosts simply push, swap and pop. There is not concept of an "end-to-end LSP" as such. We just use the term "LSP" to define an FEC. But really, each node in the FEC's path is making its own push, swap and pop decisions. The LFIB in each node need only be as large as the number of LDP-enabled routers in the network. You can get scenarios where FEC's are also created for infrastructure links, but if you employ filtering to save on FIB slots, you really just need to allocate labels to Loopback addresses only. Mark.
Current thread:
- Re: Devil's Advocate - Segment Routing, Why?, (continued)
- Re: Devil's Advocate - Segment Routing, Why? Baldur Norddahl (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Baldur Norddahl (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 21)
- RE: Devil's Advocate - Segment Routing, Why? adamv0025 (Jun 22)
- Re: Devil's Advocate - Segment Routing, Why? Masataka Ohta (Jun 20)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 20)
- Re: Devil's Advocate - Segment Routing, Why? Masataka Ohta (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Robert Raszuk (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Robert Raszuk (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Robert Raszuk (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Robert Raszuk (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 21)
- RE: Devil's Advocate - Segment Routing, Why? adamv0025 (Jun 22)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 19)
- RE: Devil's Advocate - Segment Routing, Why? adamv0025 (Jun 21)
- Re: Devil's Advocate - Segment Routing, Why? Mark Tinka (Jun 21)