MPLS Gets Real

Are Single-Mode Fiber and Lambda Switching a Bad Mix?

But while in the long-term MPLS could be the tie that binds multiple networks, most carriers adopting MPLS today aren't doing it with an eye toward convergence. They are using MPLS primarily for backbone network traffic engineering and, in some cases, to create private, secure links across IP networks.

WorldCom Inc. is a perfect example. The carrier widely has embraced MPLS in its various networks, but it shows little interest in using the technology to converge its multiple networks.

Instead, the company uses MPLS for traffic engineering in the core of its UUNet public Internet backbone, says George Kushin, WorldCom's director of IP product marketing. MPLS has been used since the fall of 1999, for backbone traffic engineering on the UUNet European network. Last year, the company began using MPLS on its OC-192 U.S. backbone, and more recently has begun using it elsewhere in the United States and in the Asia-Pacific region. The key backbone MPLS products for WorldCom in this case are Juniper Networks Inc. M40s.

On a separate front, WorldCom uses MPLS in its edge switches and routers to offer Private IP services over the company's private IP network, which is completely separate from the UUNet backbone. The key product used at the edge is Cisco Systems Inc.'s MGX 8850.

WorldCom puts VPN tags on each packet to create customer user groups with private networking-like functionality. "We assign each customer his own unique address/label and keep customer traffic separate that way," says Kushin. "We've been running that since August and formally introduced it in January."

But that private IP network runs over an ATM backbone, Kushin explains. "We don't actually use MPLS there because we're using an ATM core. We're using MPLS for the security aspects, and the core is a meshed network of ATM PVCs. We will eventually move to MPLS, but right now traffic doesn't warrant it."

This quarter. WorldCom plans to enhance its MPLS-based Private IP services by offering premium priority packet services to allow for end-to-end QoS using DiffServ-like functionality. It also plans to add a dial-in option to the MPLS network. WorldCom will marry its Private IP services with the IP VPN services running over the UUNet Technologies Inc. network (those services are based on IPsec encryption as opposed to MPLS) to give road warriors, telecommuters and branch offices remote, secure access to their companies' Private IP services.

Like WorldCom, Teleglobe Inc. uses MPLS initially for traffic engineering. Teleglobe announced this summer that its global IP network, GlobeSystem, is now 100 percent MPLS-enabled. The router technology reduces latency because it allows data to remain within the IP layer of the network while traveling point to point, instead of moving back and forth between the IP layer and the ATM and frame-relay layers of the network, the company explains. The company also expects to add new virtual networking services as a result of MPLS features.

In another WorldCom implementation, MPLS is used for traffic engineering and fast restoration on the company's Very High Performance Backbone Network Service (VBNS), a network built in 1995 for the National Science Foundation and now is used to connect research and governmental institutions.

WorldCom's senior manager of network design Ron Bonica explains that with MPLS, router configuration takes less than a second vs. seconds or tens of seconds.

"That's because MPLS has the ability to have a backup path for every label-switched path before a failure even occurs," Bonica says. "MPLS also has a function called fast restoration--every router decides what hop it would take next if there is a break."

In the late 1990s, WorldCom upgraded the VBNS with Juniper routers and deployed OC-48 packet over SONET. The backbone was no longer an ATM mesh, but instead used hop-by-hop routing, so in March 2000, the company decided to build a full mesh of Juniper routers to enable MPLS label-switched path routing.

With at least three different MPLS implementations, it's clear that WorldCom sees the benefits of the technology. But when asked if the company plans to collapse these multiple networks using MPLS--or how realistic it would be for any service provider to converge networks via MPLS--WorldCom responds with dead silence.

Fact and Fiction

Mike Abbott, CTO of Ardent Communications Inc. Internet Inc., says a lot of hype has surrounded MPLS, but those creating the hype really don't appreciate how people use MPLS.

Rather than running TDM voice, frame relay, ATM and other services all on a single MPLS-based network, as vendors are proposing, most carriers are looking at how MPLS can be used to drive better network performance and add new services , he says.

"You could do ATM over IP, but that doesn't have value," says Abbott, commenting on whether MPLS will drive network convergence. "What [MPLS] does allow you to do is provide quality of service without requiring [additional] bandwidth. ATM or frame relay would require bandwidth to do that QoS. That's an overhead issue."

Ardent has implemented MPLS across all its core and edge routers. In early July, the company was using MPLS in limited test environments for traffic engineering, VPN services, and some small tunneling for performance, as well as for hop count reduction. It also appears MPLS could be used to prevent denial-of-service attacks, adds Abbott.

He adds, the company plans to roll out MPLS-based VPN service late in the third quarter and expects to offer all its services on an IP MPLS network.

That makes sense for Ardent because the company doesn't offer frame relay and has provided ATM service only on a limited basis. But companies that offer frame relay and/or ATM to a significant number of customers see MPLS from a different angle.

For example, AT&T Corp. uses MPLS to IP-enable its frame relay services, says Don Proctor, vice president and general manager of Cisco's multiservice switching business unit.

"The big problem it solves for AT&T customers is with Layer 2 technologies like frame relay, if you want every point on a network to connect to every other point on a network, you have to build a full mesh network, and it's not a very efficient way to build networks," Proctor explains. "With the IP-enabled frame relay service, customers get any-to-any access ... all sites are one router hop to every other site."

While MPLS will not create a wholesale move to a collapsed network instantaneously, Proctor says the AT&T service is an example of how the technology gradually is allowing carriers to collapse different networking functions.

"If you were to look at my customers that have deployed MPLS, they have applied it on their frame or ATM backbones," says Proctor. "This is new for carriers, which have typically built new networks for each new service. The incremental cost of IP-enabling an ATM backbone is trivial vs. building a whole new network. So convergence is happening at this point at Layer 2 and Layer 3."

There's also a move by groups, such as the Optical Internetworking Forum, to collapse the control plane at Layer 1, he says.

Time division multiplexed (TDM) services are another story, however, because the technical community has not yet developed a way to do committed bit rates over MPLS, which TDM voice would require, says Proctor, adding working groups within the Internet Engineering Task Force are addressing that issue.

Steve Vogelsang, co-founder and vice president of sales and marketing at Laurel Networks Inc., says the AT&T example is the shape of things to come. While the initial driver of MPLS was clearly traffic engineering in core networks, the focus now is more on using MPLS to add services to an ATM backbone, he says, adding that vendors are starting to see RFPs from carriers for such applications. "We believe this will drive MPLS adoption in a big way," he says.

Metro MPLS

While MPLS has been used largely in backbone networks, it also is expanding to the edge as service providers and their vendors turn their attention to bringing more bandwidth, intelligence and services to access networks.

"We see potential for [MPLS] as a scalable, resilient technology to carry Ethernet across the access network," says Vogelsang of Laurel, a router vendor. He explains that Ethernet can handle only 4,000 VLANs per backbone, and that Ethernet is not considered "carrier class." MPLS can address some of those issues because it supports up to 1 million labels per switch, he says.

An early implementation of MPLS at the carrier edge is Portugal Telecom S.A., a customer of Unisphere Networks Inc., which is a key player in the edge router space with its ERX line of products. Karen Livoli, director of product marketing for the ERX and the data group at Unisphere says Portugal Telecom now has six financial institutions on the network, which is based on Unisphere routers, doing Internet connectivity and financial transactions.

Standard Issue

With all the interest in MPLS, support for the protocol is no longer considered an additional feature; it's now becomes a requirement.

"MPLS is going to be a long, slow rollout moving from the core to the edge," says Kevin Mitchell, directing analyst of service provider networks for Infonetics Research Inc. "But it is a must-have for any vendor at the core (new products must have proven interoperability with Cisco and Juniper as well) and must be on the road map for edge router players."

According to an Infonetics Research report completed last fall entitled "The Service Provider Opportunity in the US 2000: IXCs, RBOCs, and Tier 1 CLECs", 22 percent of Tier 1 U.S. carriers surveyed had already implemented MPLS (that is a percentage of respondents, not percentage of the network). The protocol is expected to become a network standard of choice, growing to 56 percent through 2001 and into 2002.

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