Next-hop resolution of BGP labeled routes to tunnels

The user enables the resolution of RFC 3107 BGP label route prefixes using tunnels to BGP next hops in the TTM with using following commands:

config>router>bgp>next-hop-res
        labeled-route-transport-tunnel
            [no] family family
                resolution {any | disabled | filter}
                resolution-filter
                    [no] ldp
                    [no] rsvp
                    [no] sr-isis
                    [no] sr-ospf

The transport-tunnel context allows the user to configure different types of BGP label routes: label-IPv4 and VPN routes (which includes both VPN-IPv4 and VPN-IPv6 routes). By default, all labeled routes resolve to LDP, even if the preceding CLI commands are not configured in the system.

If the resolution command is set to disabled, the default binding to LDP tunnels resumes. If resolution is set to any, the supported tunnel type selection is based on the TTM preference. The order of preference of TTM tunnels is the following:

If the rsvp option is enabled, BGP searches for the best metric RSVP LSP to the address of the BGP next-hop. The address can correspond to the system interface or to another loopback used by the BGP instance on the remote node. MPLS provides the LSP metric in the tunnel table. In the case of multiple RSVP LSPs with the same lowest metric, BGP selects the LSP with the lowest tunnel ID.

If the ldp option is enabled, BGP searches for an LDP LSP with a FEC prefix corresponding to the address of the BGP next-hop.

If the sr-isis or sr-ospf option is enabled, an SR tunnel to the BGP next-hop is selected in the TTM from the lowest preference IS-IS or OSPF instance. If many instances have the same lowest preference, the lowest numbered IS-IS or OSPF instance is chosen.

If one or more explicit tunnel types are specified using the resolution-filter option, only these tunnel types are selected again following the TTM preference. The resolution command must be set to filter to activate the list of tunnel types configured in the resolution-filter context.

Parent topic: BGP