MPLS-VPN Label

[mounir.mohamed]

In MPLS-VPN the forward of packets based on the LFIB tabel and the first label (NextHope)

label is advertised through the LDP and the second label (VPN label) is annouced via

MP-BGP, the problem is that when i check the FIB tabel of the customer VRF i can see both labels

but when i check the customer LFIB i did't see the second label=VPN!! so is that the VPN labels stors

only in the FIB and if right how is that while the forward always based on the LFIB

kindly advice

Router#show ip cef vrf cust det

10.10.44.0/30, version 1499, epoch 0, cached adjacency to Switch1.2

0 packets, 0 bytes

tag information set

local tag: VPN-route-head

fast tag rewrite with Sw1.2, point2point, tags imposed: {83 544}

via x.x.x.x, 0 dependencies, recursive

next hop x.x.x.x, Switch1.2 via x.x.x.x/32

Router#show tag for vrf cust

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

126 Untagged 10.10.52.8/29[V] 55708 Sw1.87 point2point

253 Untagged 10.10.52.4/30[V] 0 Sw1.87 point2point

263 Aggregate 10.10.52.0/30[V] 0

284 Untagged 10.230.52.0/22[V] 8616469838 Sw1.87 point2point

[mheusinger]

Hello,

the command "show mpls forwarding-table vrf cust" asks for a list of all locally assigned VPN labels! As the network 10.10.44.0/30 is learned via BGP, there is no locally assigned VPN label - hence it will not show up in the LFIB.

Another explanation would be: traffic towards 10.10.44.0/30 is received from the CE in the form of IP packets. So the PE has to perform an IP lookup and that means it is the FIB´s "business" to attach labels. LFIB has nothing to do with it. As you have seen the FIB however "knows" what to do, so everything is fine - cust is happy ;-)

Hope this helps! PLease rate all posts.

Regards, Martin