MPLS has to be most misunderstood, most miscommunicated, most over marketed technology to come along in the last 10-15 years and before I go any further I want to clarify one point as it relates to MPLS. Typically when I’m discussing requirements for a project/design I’ll ask a question pertaining to the circuit(s) involved. For instance at a head end location that is aggregating multiple remote locations, I may ask “what is the last mile circuit being dropped into the head end?” and more often than not nowadays the response I get back is, “it’s an MPLS connection” or the customer will simply say “we purchased an MPLS network from our provider” however they have yet to tell me what type of interface is used and in a lot of cases they actually believe that they will need an MPLS interface for their router. For the record we at Cisco do not make an MPLS interface, in fact you can’t purchase an MPLS interface for your router. You can check here: Cisco Interfaces and Modules. MPLS is in raw form is simply a switching mechanism internal to the router that moves a packet from one interface to another based on labels. Labels are exchanged via the glue of MPLS known as the Label Distribution Protocol (LDP) and most end customers don’t participate in the LDP exchange with their provider…notice I said most because there are in fact some customers that do but these are typically larger customers that have a National or International presence or may be another provider themselves.

Anyway on to the topic of the post. If you are considering actually running MPLS or MPLS based VPN’s on your ISR router and your looking for product positioning of the router, we have an excellent document that details where you can place an ISR in the MPLS VPN network. The whitepaper can be found here:

MPLS VPN and Multi-Virtual Route Forwarding Support for Cisco ISR