There are four designations for routers participating in MPLS connectivity:
- C Router = Customer Router (Does not peer with Service Provider, is an internal device that performs routing for the organization)
- CE Router = Customer Edge Router (Responsible for peering with the Service Provider’s Edge Routers; like the C Routers, they are also unaware of the MPLS VPN)
- PE Router = Provider Edge Router (Responsible for peering with the customer edge, provides VRF segmentation for IP VPN functionality; attaches the MPLS labels)
- P Router = Service Provider Backbone Router (Leverages Multi-protocol iBGP communities to transport customer EIGRP metrics for assembly/disassembly to/from remote sites and headquarters, etc. Hidden from the customer)
When peering EIGRP with the service provider MPLS PE Router, the SP assigns the EIGRP AS number. That is virtually all that is required of the customer.
- If a remote site has the same AS number as another, routes advertised by the PE will be internal EIGRP (90 AD) routes with no additional cost consumed by the traversal of the MPLS cloud.
- If a remote site has a different AS number than another, routes advertised by the PE will be external EIGRP (170 AD) routes with configured default metric.
Stuck-in-Active: Journal of an IT-Network Administrator 