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Optical/IP Networks

MPLS Is Growing Up

Multiprotocol Label Switching (MPLS) has beaten out Asynchronous Transfer Mode (ATM) for the carrier core, and new carrier deployments are rolling out as vendors shift their focus from getting the technology to work, to figuring out how to make money from it. “MPLS is no longer a pie-in-the-sky technology,” says Steve Vogelsang, vice president of marketing at Laurel Networks Inc. “The technology has matured to the point where we’re not talking about what cool new widget has just come out. We’re looking at how we can actually manage these networks.”

MPLS's maturity was apparent at the three-day MPLS 2003 conference in Washington, D.C. For six years the conference, organized by testing lab Isocore, has attracted the most influential MPLS engineers. Conference organizers say more than 500 registered this year, compared to last year's attendance of 350. Isocore's Bijan Jabbari says the increase was due to more service provider participation. For the first time, Bell operators took part. BellSouth Corp. (NYSE: BLS) even co-chaired the event, while Verizon Communications Inc. (NYSE: VZ) sent a representative to speak on a panel.

BellSouth, AT&T Corp. (NYSE: T), MCI (Nasdaq: MCIT), and NTT Communications Corp., among others, have already started deploying MPLS. Others, including Verizon, are in the process of selecting gear and deploying it. Even Sprint Corp. (NYSE: FON) seems to be coming around to the idea of using MPLS in certain parts of its network.

From a technical perspective, a lot has happened since the last MPLS conference in October 2002. Standards work moves forward on MPLS fast reroute, a mechanism that sets up alternative paths for sub-50ms recovery and restoration. Isocore demonstrated interoperability of the technology at the MPLS 2002 conference (see MPLS Vendors Demo Fast Reroute). Layer 3 virtual private networks (VPNs) based on the Internet Engineering Task Force (IETF) proposal 2547 also continued to grow in popularity among carriers (see MPLS VPNs: The Talk of Supercomm). Carriers are offering point-to-point Layer 2 MPLS VPN services using Draft Martini as well.

Virtual private LAN service (VPLS), the Layer 2 multipoint implementation of Layer 2 VPNs over Ethernet, has also made significant headway in the past year (see VPLS Standard Debated). The jury is still out in terms of the signaling protocols that will be used to provision the nodes, but a common standards document should be ready by the end of 2004 (see Kompella Backs BGP).

While much has been accomplished, there's still more work to do. Here’s a look at some of the most pressing issues discussed at this year’s MPLS conference:

  • Intercarrier MPLS
    Carriers have mastered the technical intricacies of offering MPLS VPNs and traffic management within a single carrier network. Now the challenge is connecting those networks to others so that end-to-end quality of service can be guaranteed. Billing issues and management between carrier domains must also be addressed.

    “MPLS is designed to be effective in a single-carrier network,” says Christian Martin, a Distinguished Member of Verizon’s engineering team. “But you can’t do traffic engineering between carriers. There are some techniques proposed, but there’s more work to be done here.”

  • Operations, Administration, Maintenance, and Provisioning
    Now that an MPLS network has been deployed, how do you manage and troubleshoot problems? ATM and Frame Relay already have trusted OAM&P mechanisms. Carriers, especially the regional Bell operators, want it for MPLS, too.

    “MPLS provides very basic monitoring and only tells you if you’ve lost a path,” says Peter Hill, vice president of technology planning and development at BellSouth. “But it won’t give you any information about what happened on that path.”

    Some vendors say that a separate OAM&P mechanism isn’t needed. Vogelsang of Laurel says that troubleshooting can be done using existing IP routing protocols.

    “OAM&P is a big deal for service providers,” he says. “But there are other mechanisms and protocols that can tell you what’s happening on the network. Of course, if that’s what customers want, we’ll give it to them.”

    The big question mark now is which organization will develop the standards. Will it be the IETF or the International Telecommunication Union (ITU)? Both groups are currently working on solutions.

  • Multicast Over MPLS
    Unlike other technologies like ATM or IP, MPLS doesn’t support a one-to-many communication method. Adding multicast capabilities would allow carriers to offer new services like video on demand for residential users. NTT has added extensions to MPLS and has been experimenting with MPLS multicast. Representatives from the carrier presented information at the MPLS 2003 conference. Juniper Networks Inc. (Nasdaq: JNPR) also claims to offer a solution.

  • Generalized MPLS
    Last but not least, engineers will continue working on integrating IP and optical signaling over MPLS. Even though the standards are still a long way off, and carriers don’t seem terribly interested in the technology just yet, vendors are already working on solutions. Isocore has already done an interoperability test of some of the GMPLS gear that’s now available. (For more on this, see today's story: GMPLS Showcased in Demo.)
— Marguerite Reardon, Senior Editor, Light Reading

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