Narbik MPLS

Remember that LDP advertises it's LDP router-id as the transport address in the LDP discovery messages and you must provide reachability for that router-id. There should be an exact match for the LDP-ID in the routing table. Pay close attention as a lot of MPLS troubleshooting scenarios seem to at least touch this topic.

'show mpls ldp discovery detail' can be key to uncovering these scenarios. If you see something like 'no host route to transport address' your router does not have the route to the LDP neighbors transport (or router-id) address. Check your IGP routing table.


BB1(config)#do sh mpls ldp disc det
 Local LDP Identifier:
    7.7.7.7:0
    Discovery Sources:
    Interfaces:
        FastEthernet0/0 (ldp): xmit/recv
            Enabled: Interface config
            Hello interval: 5000 ms; Transport IP addr: 7.7.7.7
            LDP Id: 6.6.6.6:0
              Src IP addr: 10.1.67.6; Transport IP addr: 6.6.6.6
              Hold time: 15 sec; Proposed local/peer: 15/15 sec
              Reachable via 6.6.6.6/32

'mpls ldp holdtime 90' will set the holdtime to 90 seconds, and the keep alive to 1/3 the hold timer.

When you are filtering label advertisements, you need to first disable label advertisement with 'no mpls ldp advertise-labels'. Otherwise your filtering will have no effect. The RD will make the non-unique customer IPv4 address into a unique 96-bit unique VPNV4 address. RD does not indicate which VRF a prefix belongs to and it is NOT a vpn identifier. The route-target is a bgp extended community saying which communities will be imported or exported with the specified VRF.

I finally get and understand the sham link. I just forget to put the loopback interface in the VRF! No wonder my bgp routes didn't show up!

I am slowly starting to get this SoO stuff. It's very easy to understand, but can be a bear to construct and setup.Simply use route-maps to set and filter the SoO extended communities. Chances are if you have redundant connections, you will need to set/filter SoO.

I really enjoy Narbik's MPLS labs. Something about how the labs are constructed and how he explains it makes total sense.

Now it's off to full labs....joy, joy....