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hot-root-standby (MBGP MVPN)


Hierarchy Level


In a BGP multicast VPN (MVPN) with either RSVP-TE point-to-multipoint or MLDP point-to-multipoint provider tunnels, configure hot-root standby, as defined in Multicast VPN fast upstream failover, draft-morin-l3vpn-mvpn-fast-failover-05.

Starting in Junos OS Release 21.1R1, you can configure MLDP point-to-multipoint provider tunnel on MX Series router.

Hot-root standby enables an egress PE router to select two upstream PE routers for an (S,G) and send C-multicast joins to both the PE routers. Multiple ingress PE routers then receive traffic from the source and forward into the core. The egress PE router uses sender-based RPF to forward the one stream received by the primary upstream PE router.

When hot-root-standby is configured, based on local policy, as soon as the PE router receives this standby BGP customer multicast route, the PE can install the VRF PIM state corresponding to this BGP source-tree join route. The result is that join messages are sent to the CE device toward the customer source (C-S0, and the PE router receives (C-S,C-G) traffic. Also, based on local policy, as soon as the PE router receives this standby BGP customer multicast route, the PE router can forward (C-S, C-G) traffic to other PE routers through a P-tunnel independently of the reachability of the C-S through some other PE router.

The receivers must join the source tree (SPT) to establish a hot-root standby. Customer multicast join messages continue to be sent to a single upstream provider edge (PE) router for shared-tree state, and duplicate data does not flow through the core in this case.

In case there are more than two PE routers multihomed to the source, backup UMH selection is based on the same algorithm used to select the primary UMH.

There is no limitation in Junos OS on which upstream multicast hop (UMH) selection method is used. For example, you can use static-umh (MBGP MVPN) or unicast-umh-election .

PIM dense mode as the customer multicast protocol is not supported.

Hot-root standby is supported for RSVP point-to-multipoint and mLDP point-to-multipoint provider tunnels. Other provider tunnels are not supported. A commit error results if hot-root-standby is configured and the provider-tunnel is not either RSVP point-to-multipoint or mLDP point-to-multipoint.

Fast failover (sub 50ms) is supported for C-multicast streams within NG-MVPNs in a hot-standby mode. The threshold to trigger fast failover must be set. See min-rate for information on fast failover.

When you configure hot-root-standby on MPC10 or MPC11 linecards, the failover process takes up to 150 milliseconds.

Cold-root standby and warm-root standby, as specified in draft Morin, are not supported.

The backup attribute is not sent in the customer multicast routes, as this is only needed for warm and cold-root standby.

Internet multicast is not supported with hot-root standby.

Required Privilege Level

routing—To view this statement in the configuration.

routing-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 16.1.

Support for MLDP point-to-multipoint provider tunnel is introduced in Junos OS Release 21.1R1 for MX Series router.