Finally found the missing glue:
[edit routing-options static route 10.10.2.0/24]
- next-hop 10.255.0.6;
- color 200;
+ spring-te-lsp-next-hop {
+ BLUE-TE;
+ lsp-source {
+ static;
+ }
+ }
[edit protocols source-packet-routing]
+ tunnel-tracking;
-dp
From: David Zimmerman <[email protected]>
Date: Saturday, December 13, 2025 at 2:49 PM
To: [email protected] <[email protected]>
Subject: Simple node SID TE with either SRv6 or SR-MPLS
Hi, folks. I’m activating the NANOG brain trust here because I’ve exhausted
(and am exhausted from) efforts so far to seal the deal on what is probably
simple stuff to y’all.
TL;DR: I think I’m missing some specific glue to make my backbone data plane
forward CE IPv4 traffic into a simple PE-to-PE node SID path. I’ve tried both
SRv6 steering IPv4 encap in IPv6 GRE (due to lack of End.DX4 or End.DT4) and
SR-MPLS. Anonymized and scrubbed topologies and configurations attached — Plan
E for SRv6, Plan F* for SR-MPLS. Using Junos 23.4R2-S5.6, looking for the
magic “you forgot this part” for either way (though SRv6 + IPv6 GRE preferred).
Details:
I have a video partner with CEs at two sites on my internal WAN using SMPTE
2022-7 to generate two identical video streams. I receive those on physically
diverse links from his CEs to my PEs, then ideally carry them over diverse
paths, which I need TE to do. A path of node SIDs satisfies (for now) proof
that I can do this (adjacency SIDs later). Everything I’m doing passes Junos
CLI syntax checking and “commit check” semantics, but when the change is
complete, neither I nor my partner sees this work doing ... anything. I should
see his video test patterns having a significant bump in the “blue” path
transcontinental end-to-end latency because I’m heading towards Canada then
heading towards Mexico on my way between coasts. The “red” path is almost a
straight shot.
My PEs do not run BGP, so I need to do all of this entirely within IS-IS. I
believe my use of “color” in these configurations is a distraction that sounds
like it should work but is misguided being a BGP knob. I believe I’ve
identified that IPv6 GRE on Junos will only use inet6.0 and will not get
steered by the SID path in other tables despite my trying mechanisms like
resolution-ribs.
I prefer to have this work with SRv6 because I’m greenfield and it’s kind of a
moonshot. But at this point I’ll defer to something more tried-and-true like
SR-MPLS just to get things working.
Direct responses are great, public responses are cool if there are helpful
learnings for others where my self-esteem in this space is fragile but
sacrificial :-)
-dp
* Yes, “F” now stands for what you think it does
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