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MPLS Networks

Posted on 2013-05-21
Medium Priority
Last Modified: 2013-11-13
I have a question about the MPLS networks.. I understand that there is CE-PE pair for each MPLS site.. however, beyond PE .. are there any backbone routers or do the packets directly flow over to the next PE?

I was thinking following traffic flow, up until I came across a few more routers in providers networks.

CE_1 <---> PE_1 <------------> PE_2<---->CE_2
Question by:totaram
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LVL 24

Expert Comment

ID: 39185967
MPLS routers in the backbone network are called P routers.

CE <-> PE <-> P <-> P <-> PE <-> CE.

P Router: In an MPLS Network,  a Provider (P) Router is a Label Switch Router (LSR) that functions as a transit router of the core network. The P Router typically connects to one or more PE Routers.

Author Comment

ID: 39186002
OK.. so what I hear from above is that label switching is done by the P router and not PE routers... can PE do label switching??
LVL 24

Accepted Solution

aadih earned 600 total points
ID: 39186150
PE routers maintain VPN routes for those VPNs that are members (P routers do not maintain any VPN routes and perform label switching).

A LSR (Label Switched Router) can be at the ingress or egress of the MPLS domain. It generates a label in the ingress, and removes the label at the egress.

It may be worth your while to read a good paper (there are many), e.g.:

<¿ > and read the RFCs.

Author Closing Comment

ID: 39188382
LVL 24

Expert Comment

ID: 39188389
Mention not (You are welcome).  :-)

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