MultiProtocol Label Switching

Multiprotocol Label Switching
MPLS

   <networking> (MPLS) A {packet switching} {protocol} developed
   by the {IETF}.  Initially developed to improve switching
   speed, other benefits are now seen as being more important.

   MPLS adds a 32-{bit} label to each {packet} to improve
   {network} efficiency and to enable {routers} to direct
   {packets} along predefined routes in accordance with the
   required {quality of service}.  The label is added when the
   {packet} enters the MPLS {network}, and is based on an
   analysis of the {packet} {header}.  The label contains
   information on the route along which the {packet} may travel,
   and the {forwarding equivalence class} (FEC) of the {packet}.
   Packets with the same {FEC} are routed through the {network}
   in the same way.

   Routers make forwarding decisions based purely on the contents
   of the label.  This simplifies the work done by the {router},
   leading to an increase in speed.  At each {router}, the label
   is replaced with a new label, which tells the next {router}
   how to forward the {packet}.  The label is removed when the
   {packet} leaves the MPLS {network}.

   Modern {ASIC}-based routers can look up routes fast enough to
   make the speed increase less important.  However, MPLS still
   has some benefits.  The use of {FECs} allows {QoS} levels to
   be guaranteed, and MPLS allows {IP} {tunnels} to be created
   through a {network}, so that {VPNs} can be implemented without
   {encryption}.

   MPLS Resource Center (http://mplsrc.com/).

   [RFC 3031]

   (2002-04-14)