Summary

  • RFC 10067 adds Association Type 8 so PCEP can group two unidirectional Segment Routing LSPs into an associated bidirectional pair.
  • The association exposes the reverse path at both endpoints. Liveness remains directional, and the management layer must combine those results before the service gets a two-way status.

Type 8 can name the pair. It cannot decide who gets paged when one leg fails.

RFC 10067 extends PCEP so a controller and its path-computation clients can associate two one-way Segment Routing Label Switched Paths. It applies to stateful and stateless PCEs, and to paths initiated by either the PCE or the PCC. Association Type 8 gives the pair a shared control-plane identity; explicit route objects can carry the path in each direction.

That reverse-path knowledge matters. Directed BFD and performance measurement can require an ingress node to know the path traffic will take back. Without that information, an operator may have a carefully measured outbound path and a return route treated as somebody else’s problem.

The RFC keeps path association and service health in separate boxes. Liveness detection runs independently in each direction; the management layer must correlate both results before it can call the bidirectional service operational. RFC 10067 tells operators to verify that both ends have the correct LSP association. The control plane can make the relationship legible; it cannot make two separate failure domains behave as one.

This is different from RFC 10066, which carries multiple segment lists and their opposite-direction lists for multipath operation. RFC 10067’s question is narrower: which one-way SR LSP belongs with its reverse counterpart, and what evidence is still needed after the pairing?

The RFC also leaves function and policy under operator control. PCEP may report support and success or failure counters through a YANG model, but those are implementation choices, not a new service-level guarantee. The IANA registry has assigned association type 8. RFC 10067 recommends protecting PCEP sessions with TLS because a malicious speaker could alter the association.

For a production change, record the forward and reverse LSP identifiers, the association observed at both endpoints, and a separate liveness result for each direction. Then define the rule that combines them: if either side fails, does the service page, drain, reroute or remain “partially available”? If dashboards show only “pair present,” the most important operational question has been pushed into an unnamed human decision.

The standard specifies the control-plane association, not deployment adoption or service outcomes. Public implementation and operational telemetry would establish how often operators expose both directional checks and what they do when only one succeeds.

Sources