The user enables the resolution of VPN-IPv4 and VPN-IPv6 prefixes using tunnels to MP-BGP peers using the following commands:
config>service>vprn
auto-bind-tunnel
resolution {any|disabled|filter}
resolution-filter
[no] ldp
[no] rsvp
[no] sr-isis
[no] sr-ospf
The auto-bind-tunnel context configures the binding of VPRN routes to tunnels. The user must configure the resolution command to enable auto-bind resolution to tunnels in the TTM. If the resolution command is set to disabled, auto-binding to a tunnel is removed.
If the resolution command is set to any, any supported tunnel type in the vprn context is selected following the TTM preference. If one or more explicit tunnel types are specified using the resolution-filter command, only these tunnel types are selected again following the TTM preference. The following tunnel types are supported in a vprn context in order of preference: RSVP, LDP, and segment routing (SR).
If the rsvp command is enabled, BGP searches for the best metric RSVP LSP to the address of the BGP next-hop. This address can correspond to the system interface or to another loopback that the BGP instance uses 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 command 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 command is configured, an SR tunnel to the BGP next-hop is selected in the TTM from the lowest preference ISIS or OSPF instance. If many instances have the same lowest preference, the lowest numbered IS-IS or OSPF instance is chosen.
The BGP tunnel type is not explicitly configured in VPRN resolution and is therefore implicit. It is always preferred over any other tunnel type enabled in the auto-bind-tunnel context. However, the BGP tunnel type is configurable as a new tunnel type for BGP EVPN prefixes. The user must enable the BGP tunnel type to ensure that inter-area or inter-as prefixes are resolved.
The user must set the resolution command to filter to activate the list of tunnel types configured under resolution-filter.
When configured in a VPRN service (using the configure>service>vprn>spoke-sdp command), an explicit SDP to a BGP next-hop overrides the auto-bind-tunnel selection for that BGP next-hop only. There is no support for reverting automatically to the auto-bind-tunnel selection if the explicit SDP goes down. The user must delete the explicit spoke-SDP in the VPRN service to resume using the auto-bind-tunnel selection for the BGP next-hop.