Basics of MPLS

MPLS

Multiprotocol Label Switching

Multiprotocol Label Switching (MPLS) is a routing technique or method used in high-performance telecommunications networks that directs packet or data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. The labels classify virtual links (paths) between distant nodes rather than endpoints. MPLS can encapsulate packets of various network protocols. MPLS supports a collection of technologies, such as T1, E1, DSL and ATM.

MPLS is used to speedup the traffic in a network. 

MPLS uses combination of both circuit switching and packet switching.

MPLS operation

MPLS works by prefixing packets with an MPLS header, containing one or more labels. This is called a label stack. Each label stack entry contains four fields:

A 20-bit label, 3 bit label, 1 bit label, 8 bit ttl.

These MPLS-labelled packets are switched after a label lookup/switch instead of a lookup into the IP table. when MPLS was conceived, label lookup and label switching were faster than a routing table lookup.

Routers that perform routing based only on the label are called label switch routers (LSRs). The entry and exit points of an MPLS network are called label edge routers (LERs), which, respectively, push an MPLS label onto an incoming packet and pop it off the outgoing packet.

MPLS works in conjunction with IP and its routing protocols, such as the Interior Gateway Protocol (IGP).

Dis advantage.

It does not offer encryption, for which it will enable cyber attacks in the network.

-DR