On 17/06/2020 18:38, Saku Ytti wrote:
Why do we really need SR? Be it SR-MPLS or SRv6 or SRv6+? I don't like this, SR-MPLS and SRv6 are just utterly different things to me, and no answer meaningfully applies to both.
I would ask, why do we need LDP, why not use IGP to carry labels?
Less state, protocols, SLOC, cost, bug surface
And we get more features to boot, with LDP if you want LFA, you need to form tLDP to every Q-space node, on top of your normal LDP, because you don't know label view from anyone else but yourself. With SR by nature you know the label view for everyone, thus you have full LFA coverage for free, by-design. Also by-design IGP/LDP Sync.
So no need to justify it by any magic new things, it's just a lot simpler than LDP, you don't need to need new things to justify SR-MPLS, you need to want to do existing things while reducing complexity and state.
Unsurprisingly, there would be no way on Earth that I could have said that better, so you shall find only loud cheering from over here. -- Tom