Re: [spring] “SRV6+” complexity in forwarding

[Stewart Bryant <[e-mail]>]

On 20/09/2019 09:44, Robert Raszuk wrote:
> TI - stands for Topology Independent ... all other LFA modes rely on 
> topologies to be able to compute or not the backup path.

Well so does TI-LFA.

At some level you have to know the topology to calculate *any* path in 
SR, else how do you know what links and SIDs to use. When you use loose 
source routing that is even more the case.

Moreover since TI-LFA specifies the need to align the repair path with 
the post convergence path you have to know the post convergence path to 
do that, and to do that someone must know the topology.

I think a better description for the technology is that it is not 
constrained by topology, i.e. that you can create the repair path 
regardless of the topology, although the more perverse the topology the 
more SIDs are required.

TI-LFA is only independent of the topology it that it can find a path 
regardless of the topology, not without knowledge of the topology.

- Stewart