Multiprotocol Label 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:
Ø A 20-bit label value.
Ø a 3-bit Traffic Class field for QoS (quality of service) priority (experimental) and ECN (Explicit Congestion Notification).
Ø a 1-bit bottom of stack flag. If this is set, it signifies that the current label is the last in the stack.
These MPLS-labeled packets are switched after a label lookup/switch instead of a lookup into the IP table. As mentioned above, when MPLS was conceived, label lookup and label switching were faster than a routing table or RIB (Routing Information Base) lookup because they could take place directly within the switched fabric and not the CPU.
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 [note 1] and pop it off the outgoing packet.
Alternatively, under penultimate hop popping this function may instead be performed by the LSR directly connected to the LER.
Alternatively, under penultimate hop popping this function may instead be performed by the LSR directly connected to the LER.
MPLS have two part one as mpls normal routing which replace cef work on router and is VPN which is best use of MPLS these days. MPLS replace traditional network link where companies opt point to point links.
ReplyDeleteMPLS is good for service provide side engineer , for custmoer side engineer not need to do more configuration in their environment when they opt MPLS.
Sanjay Khurana
khuranasanjay@gmail.com
Hi Sanjay,
ReplyDeleteThanks for providing an industry specific review on MPLS. In TeamXchange and escpecially in our Networks section we have started by clarifying the Basic Concepts at first which most of us fail to understand, as suggested by our Networks Expert, Manish Verma. Would love to get more of your ideas on our articles. Feel free to comment and also join the TEAM if you think its good to SHARE!!!! Till then Keep Sharing!!
Regards
TeamXchange
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