Use of l2vpn-id in a VPLS using BGP for autodiscovery
Here is the routing instance of a PE configured for using BGP for autodiscovery and LDP for setting up pseudowires. All PEs in the same VPLS must use the same l2vpn-id and the same vrf-target. If the target already identifies the VPLS, why do we need the l2vpn-id?
If a particular VPLS is meant to be a single fully connected LAN, all
its VSIs will have the same RT, in which case the RT could be (though
it need not be) an encoding of the VPN-id. A VSI can be placed in
multiple VPLSes by assigning it multiple RTs.
Note that hierarchical VPLS can be set up by assigning multiple RTs
to some of the VSIs; the RT mechanism allows one to have complete
control over the pseudowire overlay that constitutes the VPLS