Enterprises are now reaping the benefits of MPLS technology that was created in 1997 to bring more ATM-like characteristics to IP. Companies looking to improve QoS, facilitate any-to-any communications and converge several legacy and next-generation services on a common infrastructure are taking a long look at MPLS.

The Securities Industry Automation Corporation (SIAC), for example, is implementing MPLS VPNs as the basis of its Secure Financial Transaction Infrastructure (SFTI), a network constructed after Sept. 11, 2001, to provide a bulletproof Ethernet access infrastructure for the New York Stock Exchange, the American Stock Exchange and other financial institutions.

Customers connect via an IEEE 802.1q Ethernet virtual LAN tag port to a SFTI edge router, and then that VLAN is mapped into an MPLS VPN tunnel. The tunnel carries the customer connection to the SFTI service edge router, which connects the customer to the service network - such as one that supplies real-time quotes - that corresponds with the VPN tunnel and VLAN tag ID.

MPLS helps segment and secure customer traffic for SIAC. For the State of Illinois, it reduces complexity. A fully meshed MPLS-based RFC 2547 Layer 3 VPN enabled Illinois to collapse two separate statewide networks - one being frame relay - yet maintain traffic separation between agencies by replacing frame permanent virtual circuits (PVC) with MPLS label-switched paths

To support sites with non-routable legacy traffic, Illinois opted for Layer 2 frame relay-over-MPLS VPNs. This keeps SNA, IPX and DECnet in its frame relay PVC, which is then carried inside an MPLS label-switched path.

But MPLS is not for everyone - the touted benefits of convergence, data center virtualization, flexible bandwidth and cost savings depend on the size, needs and budget of a company, and could be offset by the need to familiarize staff with a new way of doing things and an implementation that may take more time than expected to get off the ground.

"When you're looking at an enterprise MPLS implementation you have to ask yourself, are you doing this because it's strategic in nature or are you reacting to what carriers are telling you should be doing?" says Ken Owens, senior architect at financial firm AG Edwards. "It's not easy. It's not just 'Boom,' plug-and-play."