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Source Packet Routing in Networking (SPRING) or Segment Routing

  • Support for SRv6 micro-SIDs in IS-IS transport (MX Series)—Starting in Junos OS Release 23.4R1, you can compress multiple Segment Routing for IPv6 (SRv6) addresses into a single IPv6 address (the micro-SID). Typically, if a packet needs to traverse multiple nodes, IS-IS can stack up the SRv6 segment identifiers (SIDs) using a segment routing header. This stacking of SIDs adds to the bandwidth overhead and the segment routing header processing overhead.

    You can now compress the SID list to a single destination address (the micro-SID) and reduce the bandwidth overhead. Segment routing headers can typically allow a stack of only six SRv6 SIDs. For use cases that need to include more than six SRv6 SIDs, micro-SIDs can help in compressing multiple IPv6 addresses.

    [See How to Enable SRv6 Network Programming in IS-IS Networks and micro-sid.]

  • SRv6 dynamic SID support for BGP and IS-IS protocols (MX Series)—Starting in Junos OS Release 23.4R1, we support dynamic segment identifiers (SIDs) for BGP and IS-IS.

    To enable dynamic end SID, include the dynamic-end-sid at the [edit protocols isis source-packet-routing srv6 locator locator-name] hierarchy level.

    To enable dynamic end x SID, include the dynamic-end-x-sid at the [edit protocols isis interface int-name level level-numbersrv6-adjacency-segment protected locator locator-name] hierarchy level.

    [See.level and srv6]

  • Mitigate traffic congestions using tactical traffic engineered (TTE) tunnels (MX240, MX480, and MX960 )—Starting with Junos OS Release 23.4R1, you can avoid congestions on oversubscribed links or domains using the dynamic tactical traffic engineered (TTE) tunnel solution. The dynamic TTE tunnel solution allows you to define congestion for a link by configuring high and low bandwidth thresholds. If the traffic load on the link exceeds the high threshold, then load-sharing is increased. If the traffic load falls below the low threshold, then load-sharing is decreased.

    The TTE solution helps you to:

    • Load-balance traffic towards destination prefixes using the congested outgoing interface or through a dynamically installed Tactical TE (TTE) tunnel..

    • Monitor the cumulative load and subsequent deactivation of the TTE tunnel(s) when congestion is no longer detected.

    To enable congestion protection, include the congestion-protection statement at the [edit routing-options] hierarchy level. Define high and low bandwidth thresholds by including the high-threshold and low-threshold statements at the [edit routing-options congestion-protection template template-name] hierarchy level. You also need to include the export isis-export statement at the [edit protocols isis] hierarchy level.

    The TTE tunnel solution supports ISIS and uses TI-LFA backup routes for congestion mitigation.

  • BGP classful transport support for IPv4 DTM segment routing traffic engineered (SR-TE) tunnels (MX10004)—Starting in Junos OS Release 23.4R1, we support transport-rib model for V4 DTM SR-TE tunnels by configuring the use-transport-class statement at the [edit dynamic-tunnels tunnel-name spring-te] hierarchy level.

    If the use-transport-class statement is not configured then catch all route and application route is created in the inetcolor.0 table. If the use-transport-class statement is configured then catch all route and application route is created in color.inet.3 table. This behavior is irrespective of including the use-transport-class statement at the [edit protocols source-packet-routing] hierarchy. For dynamic tunnels, SR-TE honors the use-transport-class statement under the dynamic-tunnel configuration rather than source-packet-routing configuration.

    The following IPv4 endpoint for DTM SR-TE tunnels with transport-rib model is supported:

    • DCSPF support (using compute-profile)

    • Dynamic segment list support. Configured segment list must not have any IPv6 address and MPLS SID based of IPv6.

    • Delegation to PCEP controller

    • sBFD support

    • SPRING-TE route is added only into color.inet.3 table

    For IPv4 endpoint for DTM SR-TE tunnels with inetcolor.0 model, if the use-transport-class statement is configured under SR-TE, then dynamically triggered SR-TE tunnel routes is created in both inetcolor.0 table and color.inet.3 table. The use-transport-class statement under dynamic-tunnels hierarchy decides if the SR-TE tunnels need to be placed in color.inet.3 table. SPRING-TE route is added only into inetcolor.0 table for DTM SRTE tunnels for IPv4 endpoints and inetcolor.0 model.

    Traffic steering based on extended color community is supported. For transport-rib model for DTM SR-TE tunnels (IPv4 destinations only), enable the computation and setup of interdomain segment routing paths using express-segments with SR-Policy underlay.