Hi,

Well in the MPLS core you will have a routing protocol, ospf/isis, and when you run LDP/TDP for MPLS labels then every route with be assigned its own label value by each router.

This consumes a lot of resources, cpu & memory etc.

In a normal MPLS Setup, the P routers (the routers of the SP that do not connect to customer routers) are only involved in label forwarding from PE to PE, (PE connects to customer) and this forwarding will be between a pair of PE router loopback address, as BGP is used for MPLS VPN and the loopback address is the next-hop address for the remote CE VPN routes.

So basically, we only really need to label switch the PE loopback address, so by doing this we save resources.

HTH

LR