Multisite and outsourced IT operations are making good use of Multiprotocol Label Switching (MPLS), but strange trouble is turning up more and more. Often in discussion with local network staffers, we come to the point when I ask about backhaul lines or internet service providers over which they presumably run a site-to-site virtual private network (VPN). They happily reply, "Oh, we have MPLS" and provide a network diagram consisting of a suitably inscrutable cloud.
Life is not so simple. Increasingly, those IT infrastructures appear functional, but a simple scan turns up many times the number of hosts that ought to be visible. Finding rogue devices on a network is cause for a bit of alarm, but unknown subnets?
What's going on? MPLS is supposed to simplify wide-area networking with carrier-grade service, not increase the risks of exposing sensitive data. Finding one's network cross-connected with another organization is not something that can be dealt with tomorrow, and a serious address-space collision can put networks completely out of commission.
IT managers and technologists looking for a simple way to connect distant LANs turn to MPLS as a solution that has more currency and expandability than older offerings. The trouble is many of them make the decision to adopt MPLS without enough information.