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Routing Protocols

  • IS-IS link delay measurement and advertising (MX Series)—Starting in Junos OS Release 21.1R1, you can measure and advertise various performance metrics in IP networks with scalability, by using several IS-IS probe messages. These metrics can then be used to make path-selection decisions based on network performance.

    [See How to Enable Link Delay Measurement and Advertising in IS-IS, delay-measurement, and delay-metric.]

  • Support for configuring multiple independent IGP instances of IS-IS (ACX Series, MX Series, and PTX Series)—Starting in Junos OS Release 21.1R1, you can configure and run multiple independent IGP instances of IS-IS simultaneously on a router.


    Junos OS does not support configuring the same logical interface in multiple IGP instances of IS-IS.

    [See How to Configure Multiple Independent IGP Instances of IS-IS.]

  • SRv6 network programming in IS-IS (MX Series with MPC10 and MPC11 line cards)—Starting in Junos OS Release 21.1R1, you can configure segment routing in a core IPv6 network without an MPLS data plane. This feature is useful for service providers whose networks are predominantly IPv6 and have not deployed MPLS. Such networks depend only on the IPv6 headers and header extensions for transmitting data. This feature also benefits networks that need to deploy segment routing traffic through transit routers that do not have segment routing capability yet. In such networks, the SRv6 network programming feature can provide the flexibility to leverage segment routing without deploying MPLS.

    To enable SRv6 network programming in an IPv6 domain, include the srv6 statement at the[edit routing-options source-packet-routing] hierarchy level.

    To advertise the Segment Routing Header (SRH) locator with a mapped flexible algorithm, include the algorithm statement at the [edit protocols isis source-packet-routing srv6 locator] hierarchy level.

    To configure a topology-independent loop-free alternate (TI-LFA) backup path for SRv6 in an IS-IS network,include the transit-srh-insert statement at the [edit protocols isis source-packet-routing srv6] hierarchy level.

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

  • Support for BGP Auto-discovered Neighbor (MX Series, PTX1000, PTX10008, QFX5120-32C, QFX5200, QFX5210, and QFX10008)—Starting in Junos OS Release 21.1R1, we support BGP auto-discovered neighbors using IPv6 Neighbor Discovery Protocol (ND). With this feature, you can enable BGP to create peer neighbor sessions using link-local IPv6 addresses of directly connected neighbor devices. You need not specify remote or local neighbor IP addresses.

    To enable peering for a given interface or set of interfaces without specifying the local or remote neighbor addresses, configure the peer-auto-discovery statement at the [edit fabric protocols bgp group <name> dynamic-neighbor <name>] hierarchy level.

    [ See BGP Auto-Discovered Neighbors, and peer-auto-discovery.]