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MPLS LDP and LSPs

Sorry about this, but have the MPLS and VPN Cisco press book and am just confused (in thoery) about one point.

Will setup a MPLS frame implementation for the first time this evening :)

Here you go......

You have LSPs witch determined the entire MPLS path from ingress to egress correct?

You have an LDP which distributes labels between LSRs

Now, the way I understand it, is that the LDP creates the LSP for a particulat prefix again, correct?

So,

The LSP (as I said, is the entire path from ingress to egress), is this entire LSP stored on all LSRs in the path of the MPLS network, or just on ingress and egress? Or is only one label stored on each LSR for a prefix?

1 REPLY
Cisco Employee

Re: MPLS LDP and LSPs

The Label Switch Path (LSP) is the path from the edge LSR or ingress LSR to the egress LSR. Any router in the MPLS cloud can be used as either an ingress or egress LSR.

From each LSR's standpoint, the LSP consists only of a inbound input label/output label/output interface or an IP prefix/output label/output interface if it is the case of an edge LSR.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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