[c-nsp] SR-TE

[aaron1 at gvtc.com]

Also, it works with these explicit paths as well... learned a few things
here, you can blackhole your traffic if you don't know your SID's... I used
an adjacency sid from my previous eve-ng lab on my diagram, and I forgot
that I had moved to a new lab, when I stood up the new lab, the adjacency
sids were different, 24001 instead of 24002 on my of my transit
links...between r24 and r23...

All these explicit paths work...

all prefix/node sids...

  segment-list name my-srte-sidlist-2
   index 1 mpls label 16024
   index 2 mpls label 16023
   index 3 mpls label 16022

combination of prefix/node sids and an adjacency sid...
 
  segment-list name my-srte-sidlist-2
   index 1 mpls label 16024
   index 2 mpls label 24001
   index 3 mpls label 16022

an ip address, and adj sid, and a prefix/node sid... the ip address for the
first segment is apparently is an IOS-XR trick that resolves the ip to the
prefix sid of that hop...

  segment-list name my-srte-sidlist-2
   index 1 address ipv4 10.20.0.24
   index 2 mpls label 24001
   index 3 mpls label 16022

an ip address a couple hops away but is in the igp direction that I desire,
and adj sid on the link to the last hop... 

  segment-list name my-srte-sidlist-2
   index 1 address ipv4 10.20.0.23
   index 2 mpls label 24000

all those work for my desired SRTE path... the all result in the ce traffic
taking the atypical anti-igp path... some result in different mpls tagging,
but, all cases end up being 3 tags and follow the correct, desired path.

Here's the trace of that last sedment-list (ip to 10.20.0.23, and adj sid
24000)...

ce1#traceroute 1.1.1.2
Type escape sequence to abort.
Tracing the route to 1.1.1.2
VRF info: (vrf in name/id, vrf out name/id)
  1 1.0.0.1 47 msec 41 msec 41 msec
  2 10.20.1.21 [MPLS: Labels 16023/24000/24001 Exp 0] 229 msec 229 msec 215
msec
  3 10.20.1.25 [MPLS: Labels 24000/24001 Exp 0] 238 msec 211 msec 227 msec
  4 10.20.1.9 230 msec 225 msec 222 msec
  5 1.1.1.2 314 msec *  302 msec


-Aaron