Traditional IP networks have no means of tagging, cataloging, or monitoring the packets that cross them. MPLS technology
works to solve those shortcomings of IP, placing labels on IP packets and providing the labeling function. MPLS is not designed to replace IP, it is deigned to add a set of rules to IP so that traffic can be classified, marked, and policed.

An MPLS network can offer the quality of service guarantees that data transport service like frame relay (FR) or ATM give, without requiring the use of any dedicated lines.

MPLS is contributing to the rapid growth of VPNs as it provides the SPs and network operators simpler means of adding VPN services to their portfolios and a simpler means of provisioning VPNs to their customers without having to install new hardware. Basically, an alternative to IPSec-based VPN technology, MPLS is layer 2 independent since it works on frame and cell-based networks and has layer 3 functions for IP routing. Like IP-VPNs, it provides a virtual circuit through the network.

Lately the trend has been that MPLS is getting pushed into access networks. In terms of business services, a number of vendors are now offering equipment that extends MPLS pseudo-wires to customer premises equipment. According to industry experts, the next potential use of MPLS could occur in the residential service market, supporting bundled and triple-play services.

Paths through the network created with MPLS labels, called pseudo-wires, appear to customers like separate circuits. MPLS can create multi-point networks efficiently, whereas doing the same thing with another technology such as FR or ATM would mean setting up a series of permanent virtual circuits.

With MPLS there is no difference between five customer offices in a metro or five customer offices in five different continents. A primary advantage of MPLS is that it provides the scalability to support both small and very large-scale VPN deployments.

Most carriers run MPLS underneath a wide range of services, including FR, wide-area Ethernet, native IP, and ATM. Advantages accrue primarily to the carriers. User benefits include lower cost in most cases, greater control over networks, and more detailed QoS.

Today MPLS is competing with managed leased lines. For an organization with point-to-point connectivity, MPLS is a cost-effective alternative as it is distance neutral. The majority of today's applications tend to be client/server, which generate hub-and-spoke traffic patterns. For these, switching to MPLS wouldn't show much in terms of cost. However, organizations globally have reported around 10 percent cost savings as compared with legacy FR or ATM. But the scenario changes dramatically when MPLS is used to converge voice and video-or with next-generation software architectures. Many firms have claimed immediate savings of up to 25 percent or more when they combined voice and video traffic over an MPLS WAN. Generally, video is carried over ISDN circuits, which are expensive. Consolidating this traffic onto a data network can eliminate the need for an ISDN network, generating immediate savings.

Banking is one industry that has been actively involved in evaluating MPLS, followed by manufacturing. Greenfield operations the likes of ITeS and BPO-which generally deploy next-generation computing infrastructure such as Web services, peer-to-peer or grid computing, and often requires QoS capability-are also driving MPLS.

As the tariffs are expected to drop further MPLS-if viable for your organization-would be a cost-efficient alternative. MPLS improves IP scalability and quality of service by creating virtual label-switched paths (LSP) across a network of label switching routers (LSR). GMPLS' primary enhancement to MPLS is its capability to establish connections at layer 1.

The aim of GMPLS (an improvement over MPLS)-both peer and overlay models-is to extends the reach of MPLS from routers through to the optical domain, where forwarding decisions are based on time slots, wavelengths, or physical ports (called 'implicit labels' in GMPLS terminology), not packet boundaries. GMPLS is expected to help service providers dynamically provision bandwidth and capacity, improve network restoration capabilities, and reduce operating expenses. New revenue-generating services such as optical VPNs also might spiral from GMPLS. Another anticipated gain comes from GMPLS supporting open standards. This will allow carriers to use best-of-breed equipment as they build out their networks.

Minu Sirsalewale