I dont understand the purpose of MPLS

I understand that the aim is to go from one PE to another PE.
However, I dont understand why traffic has to go through P routers.
What I mean is: Why cant the two PE routers be directly connected through wavelength multiplexing?

In my ISP I have two service provider edge routers (let's call it A and B).
I also have two retail provider edge routers (let's call it C and D).

There are virtual forwarding instances between A to C, A to D but NOT A to B.
Can anyone explain to me what could be a possible reason?
Thanks.

Comments

  • srgsrg Posts: 140Member
    Theres nothing that dictates you _MUST_ have P routers, if you want to connect PE routers back to back you're totally free to do so. Though physically meshing all your PE routers won't scale for long.
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