Source Packet Routing in Networking (SPRING) or Segment Routing

SRv6 unreachable prefix announcement (ACX7100-32C, ACX7100-48L, ACX7332, ACX7348, ACX7509, ACX7024, ACX7024X, PTX10002-36QDD, PTX10004, PTX10008, and PTX10016)— To ensure scalability and prevent overwhelming all nodes with every prefix, route summarization at area border routers (ABRs) conceal local domain details. Segment Routing for IPv6 (SRv6) further streamlines route summarization and condenses locators from remote domains and disseminates them into the core network, which can obscure local domain activities.

A provider edge router does not immediately detect the loss of reachability when a remote edge device becomes unreachable, resulting in a traffic drop until BGP sends a status update. The ABR assigns a maximum metric to prefixes from unreachable devices, ensuring they leak across domains as Unreachable Prefix Advertisements (UPAs).

To enable the UPA, include the prefix-unreachable statement at the [edit protocols isis] hierarchy level.

[See prefix-unreachable.]
BGP-LS advertisements of PCE delegated and initiated SRv6 TE tunnels (ACX7100-32C, ACX7100-48L, ACX7332, ACX7348, ACX7509, ACX7024, and PTX10002-36QDD)—Report static Segment Routing for IPv6–Traffic Engineering (SRv6-TE) tunnels with static segment list with micro SID (uSID) configuration to Path Computation Element (PCE). When the PCE controller provisions an SRv6-TE tunnel with uSIDs, BGP-LS advertises the SRv6-TE tunnel with its uSID segment list. This feature supports the SID Structure TLV 1252 and the SRv6 endpoint behavior TLV 1250, which are now available in the PCE report. When the externally controlled and routed SRv6-TE receives a PCUpdate message with uSIDs from the controller, BGP-LS advertises the endpoint behavior of the uSIDs.

[See Enable Segment Routing for the Path Computation Element Protocol and SRv6-TE Tunnels with micro-SIDs in PCEP .]