LFIB table and VPN Label

Rojer-bkk · ‎04-02-2009

Hi

pls help to clear my idea

1. next-hop field in LFIB table is outgoing interface or next-hop IP address

2. what's different between RT and VPN label ?

Thanks

Giuseppe Larosa · ‎04-03-2009

Hello Rojer,

1)

you can see the LFIB table using

sh mpls forwarding both an outgoing interface and an ip next hop can be present

example from real network

RT-MI-SMP-P6-BB-E-1#sh mpls forw 10.80.0.7

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

111 465 10.80.0.7/32 134989658 Gi1/2 10.36.192.110

RT-MI-SMP-P6-BB-E-1#

2) Route-target provides a route color and it is used in the control plane to decide if a vpnv4 route has to be imported or not in a local VRF table.

the VPN label is used in the forwarding plane and it is signalled in vpnv4 address family: it tells what inner label has to be used to send packets for an IP prefix in VRF.

The VPN label is sent with the BGP vpnv4 update and is taken from the local node label space that is only one and used by LDP, RSVP and MP-BGP.

the label has to be unique on the PE node that is connected to the VRF.

So they are two different objects and both are needed

Hope to help

Giuseppe