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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 .]

  • SRv6 SR-TE binding SID support(ACX7348)— Binding SID (BSID) segregates the network into multiple traffic engineering (TE) tunnels. You can allocate Segment Routing over IPv6 (SRv6) BSIDs under an SRv6-TE tunnel to reduce the stack size at the ingress node. The ingress node stores only a subset of TE database from other domains and transit nodes with the binding SID handles convergence. SRv6 binding supports both classic and micro SIDs (uSIDs).

    [See Binding SID (BSID) for Static SRv6 TE Tunnels]

  • Support for SRv6-TE path computation (ACX7024, ACX7100-32C, ACX7348, and ACX7509)—Segment Routing for IPv6-Traffic Engineering (SRv6-TE) path computation enhances your IPv6 network's routing efficiency by enabling the local computation of SRv6 TE paths using both classic SIDs and micro SIDs (uSIDs). You can embed explicit paths within IPv6 packets, optimizing routing paths and reducing overhead. By default, SRv6-TE path computation prefers uSIDs over classic SIDs, resulting in paths that may consist entirely of micro SIDs, classic SIDs, or a combination of both.

    [See Understanding SRv6 TE Tunnel Local Path Computation].