An Overview of MPLS and Constraint Based Routing

Multiprotocol Label Switching provides a virtual path capability between packet (label) switches to efficiently carry differentiated services across the Internet. Additionally, MPLS has been enhanced with the capability to precisely engineer traffic tunnels to avoid congestion and utilize all available bandwidth in an efficient manner. This paper provides an extensive resource, serving the motivation for MPLS and traffic engineering. General issues such as setting up the Label switching paths, Label substitution and retention schemes are addressed in the first part of the paper. The core value of MPLS is then described followed by a brief comparison of two MPLS protocols: RSVP (Resource reservation protocol) and CR LDP (constraint based routing Label distribution protocol) dealing with integration of MPLS with Quality of Service. The last section provides simulation results and analysis of a MPLS network scenario.