Hi,
Pseudowires are really useful in my network.
I have a number of DCs in different locations connected by my core network.
Imagine that a customer wants connect two rack in different DC toghether (put both on the same VLAN). Yes you can use a firewall and a VPN but what I can provide is a pseudowire that runs directly on my MPLS enabled corenetwork. An effect of that is the fact that I'm providing additional cable in both racks and in between them I'm adding the pseudowire configuration. From a customer point of view, he recieves a cable connecting both racks together. I can create a big about of pseudowires without any cost since they are already supported in hardware in my network and the customer saves money on VPNs or he can run all on top of pseudowire if he wishes to.
Even better, imagin that I have a customer with three separate racks in three different DCs. Thanks to VPLS that is an easy configuration-wise extention of EoMPLS, I'm able to do the same thing but connect these three racks toghether and use my core network as a "logical switch". In an effect all three cabs will think that they are connected to one and the same VLAN. This idea can scal up really well and again is already supported by my core network without any additional investment.
Pseaudowire as you can imagine is a logical wire, kind of a VPN but running durectly on MPLS without encryption.
If you own a core network connecting DCs or campus networks using pseudowires you can easily create redundant tunnels to separate needed traffic.
I hope that make sense fot you!
