Is it correct to assume that MPLS edge routers can route packets into and through third party networks? By this I mean, networks that are not label switched networks. The diagrams they show of the big cloud in between edge routers suggests that there is some transparency over arbitrary networks. The edge router sets up a pseudo wire to the destination router, but this can traverse arbitrary routers. How is this accomplished?

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  • Just so I don't make any assumptions, do you have an example of what kind of diagram you're talking about? Jun 25, 2015 at 14:28
  • I added an image.
    – user442920
    Jun 25, 2015 at 16:02

1 Answer 1


In the diagram you posted, the provider network is in fact a label switched network. The "P" designation on the routers usually implies that they are LSRs. It is depicted as a cloud because from the customer's point of view, the physical connections between the provider routers are unimportant. Pseudowires and other tunneling modes are accomplished through label switching.

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