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what is the difference between 1)point to multipoint LSPs and 2)multipoint to point LSPs.

I think VPLS comes under 1,but what abt 2

Cisco Employee

Re: LSPs

I'm not sure what you mean by multipoint to point LSP. I have never heard of such a thing.

On the other hand, although VPLS implement a point to multipoint L2 frame distribution, it uses a series of point to point LSPs to carry the frames between all the PEs.

There is a concept of point of multipoint LSP that is currently being developed for TE and LDP but not yet available.

Hope this helps,

Harold Ritter
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Re: LSPs


1) point to multipoint LSP

A LSP is basically a sequence of LFIB entries in consecutive label switch router (LSR) used to forward traffic also called FEC (forward equivalence class) in this environment.

Now the only traffic I am aware of being forwarded "point to multipoint" would be multicast traffic. There is an RFC on this topic:

RFC3353 "Overview of IP Multicast in a Multi-Protocol Label Switching (MPLS) Environment"

2) multipoint to point LSP

This term triggers in my memories the term "vc-merge". It is used in a cell-mode MPLS environment, where VPI/VCI values are used as forwarding labels through an ATM cloud. The LSP is then a VC. VC-merge allows to receive different ATM cells with different VPI/VCI and forward them with one VPI/VCI value. In other words many incoming VCs (LSPs) are forwarded outgoing on a single VC (LSP).

You can read more about the details in "MPLS over ATM: VC Merge" found at

This is implemented f.e. in Catalyst 8510.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: LSPs


My query abt MP 2 P LSP was based on a new draft draft-ietf-mpls-ldp-p2mp-00.And this draft defines MP 2 P LSP as

MP2P LSP: A LSP that has one or more Ingress LSRs and one unique Egress LSR.

I am just wondering abt the application of an MP2P

LSP in a live scenario.Seems this can be useful in multicasting in MPLS environment.But can anyone expaian briefly an application in which this can be used..

Re: LSPs


after reading the draft: it mentiones P2MP LSP and MP2MP LSP.

P2MP would be for multicast traffic (Cisco IP/TV solution as an example)

MP2MP would be f.e. useful in an IP Video conferencing application, where video streams need to be distributed among conference participants.

The draft does not mention MP2P, though this could be seen as a specific case of MP2MP.

Hope this helps! Please rate all posts.

Regards, Martin

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