Please, imagine two PE routers directly connected by 1GE and one 10GE interfaces and there is one RSVP-TE LSP per link connecting both PE routers. Thay are running MP-BGP from their respective loopback interfaces.When a L3VPN is configured in both PEs:
* Which is the criteria to select the LSP for a L3VPN between both PEs? The LSP preferred by the IGP to reach the peer's loopback interface, so the LSP on the 10GE interface?
* Is there any way to manually impose the LSP used by a L3VPN?
* Is there any way to load balance L3VPN traffic between both LSPs?
Sorry if my questions are pretty basic, but honestly I couldn't find any document able to explain L3VPN's behaviour on this topology.
Thank you very much
I realize that having to specify the alternate next hop on all VRF can be cumbersome but this way you have a greater granularity. For instance, you could potentially have a different next hop for each and every VRF, which in turn could use a different tunnel. Not scalable but flexible.
If what you are trying to achieve is to use the same tunnel interface for all VRFs, you could simply establish your VPNv4 session using a separate loopback address and have that loopback address reachable via a tunnel interface via a static route.
The cost of the RSVP TE signalled LSP is determined by the best IGP cost to the tunnel tail end. In your scenario, both LSPs would have the exact same cost, which would be the IGP cost via the 10g interface. Assuming you are using "autoroute announce" to inject traffic into the LSPs, the l3vpn traffic would be load balanced over the two links by default.
You can change the default behavior to prefer the LSP going over the 10gig link by using "tunnel mpls traffic-eng autoroute metric". You could also load balance between unequal bandwidth links using "tunnel mpls traffic-eng load-share".
If you want to manually set the tunnel used for a given VRF, you can do this by using a different next hop for that VRF and have a static route for that specific next hop point to the given TE tunnel. To change the next hop for a specific VRF, you would use "bgp next-hop" under "ip vrf " .