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I always broke MPLS-TE into two categories - traffic engineering for bandwidth, and fast reroute (FRR). Bandwidth engineering, like Bruce said, was religion fo

I always broke MPLS-TE into two categories - traffic engineering for bandwidth, and fast reroute (FRR). Bandwidth engineering, like Bruce said, was religion for some people and anathema for others. It saved at least one company from bankruptcy, letting them run the network they had much hotter than IP would have. FRR, though, was an absolute game-changer. Local protection to failure and sub-50ms (often sub-10ms) protection switching in an IP network? Immensely valuable. Link connectivity protection was easy to deploy and I will argue made a massive difference in an Internet network's ability to provide real-time services in the face of failure. Node protection and bandwidth protection? Less so. But MPLS-TE-based FRR was the first local protection mechanism that didn't require you to have a specific topology and which could cover 100% of all connectivity failures. I'm surprised Bruce didn't call out this distinction, because they really are two separate things using the same underlying tech.

nu11ptr 4y ago
There is no doubt FRR had value, but like all tech, there was a complexity that came with it, so it really only made sense for certain applications. Heavy voice/video networks were a no brainer, but other TCP-based applications that were less sensitive were of less value, esp. as IGP convergence improved.
- great_wubwub 4y ago
  Yeah, for sure. I'm not saying FRR was always the right answer for all questions, but for a good decade or more it was a pretty solid choice, and particularly with auto-tunnel, it was easy to do. RSVP was far too complex a hammer for just FRR, and I like SR-LDP for FRR now, but from maybe 1998 (?) to 2015 (?) MPLS-TE FRR was the best tool we had.
drbruced 4y ago
Saving it for another post. It is actually just as controversial as there was a lot of work to improve convergence times in standard IP routing at the same time.

nu11ptr 4y ago

There is no doubt FRR had value, but like all tech, there was a complexity that came with it, so it really only made sense for certain applications. Heavy voice/video networks were a no brainer, but other TCP-based applications that were less sensitive were of less value, esp. as IGP convergence improved.

great_wubwub 4y ago
Yeah, for sure. I'm not saying FRR was always the right answer for all questions, but for a good decade or more it was a pretty solid choice, and particularly with auto-tunnel, it was easy to do. RSVP was far too complex a hammer for just FRR, and I like SR-LDP for FRR now, but from maybe 1998 (?) to 2015 (?) MPLS-TE FRR was the best tool we had.

drbruced 4y ago

Saving it for another post. It is actually just as controversial as there was a lot of work to improve convergence times in standard IP routing at the same time.