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What is the main difference between bgp and mpls

Guys anyone can give the great answer please.

thanks!

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2 REPLIES
Cisco Employee

What is the main difference between bgp and mpls

Sherwin,

This question could take hours of explaining Suffice it to say, though, that BGP is a routing protocol that distributes information about reachable networks and paths towards them, while MPLS is a technology that adds additional labels to packets as they are transported over a network, and routers then perform their forwarding decisions based on the value of the label instead of packet header contents.

There is a relation between MPLS and BGP: apart from reachable networks, BGP is also capable of advertising label values assigned to individual destination networks so routers can know how to label packets for those particular destinations. However, MPLS can also work without BGP, and BGP does not require in any way that MPLS be used (in fact, BGP was created long before MPLS).

Best regards,

Peter

Super Bronze

Re: What is the main difference between bgp and mpls

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Posting

BGP (border gateway protocol) is a routing protocol.  Personally I consider it sort of a super RIP.

MPLS (multiprotocol label switching) is tag switching, very much like L2 switching.  However, it uses MPLS tags, appended to L3 packets (much like L2 VLAN tags are appended to a frame) to make a switching forwarding decision much like a L2 switch makes a switching forwarding decision using L2 MACs; also MPLS tags can be dynamically updated across MPLS switches.  As Peter notes, BGP might be used to update MPLS tags.

BTW, a principle initial reason for MPLS was to provide a faster method of making L3 forwarding decisions.  It's much, much simpler (and used to be much faster) to deal with fixed size labels than to deal with variable length IP prefixes.  Newer hardware now allows traditional routing forwarding to be about as fast as fixed size switching.  But, MPLS has other properties, for example, much like VLAN tags can be used to create virtual LANs, MPLS labels can be used to create virtual L3 domains.

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