Is Carrier Ethernet Edging Out MPLS?

There’s been a lot of talk in recent months about how the widespread adoption of carrier Ethernet will affect the transport network. Most believe SONET is on its way out as a transport technology — at least in the long term. In the meantime, BT, Nortel Networks and several vendors have talked about a new transport option called PBT; at the same time, something called T-MPLS has cropped up.

So, just what does all this mean for MPLS, a not-so-aged technology that’s widely used in network backbones? For years, folks have talked about how MPLS is poised to push beyond the core. Has carrier Ethernet now stunted its growth?

That important question moved center stage when Nortel came out with PBT, which BT subsequently latched onto, says Sam Masud, principal analyst with Frost & Sullivan. MPLS is great for converged networks, he says, the question is: Does it move into the metro? (Read “Nortel to Provide PBT-based Ethernet for BT’s 21CN.”)

Cisco Systems Inc., which invented MPLS when it came up with the concept of tag switching, and the other router vendors still are pushing for MPLS to grow beyond the core, he says. “Alcatel [Lucent] very much believes in MPLS because they have an Ethernet switch and metro service edge router (through the TiMetra acquisition), and they want MPLS in the metro for Ethernet to behave like a carrier-class technology,” Masud adds.

However, routers, which operate at Layer 3, are inherently more expensive than Ethernet switches, which operate at Layer 2, he says. That can make MPLS in the metro an expensive proposition, he continues, adding that any time you move up the OSI stack, things get more complicated. Another issue, according to Masud, is that in the core of the network you’re not going to need a lot of connections, but you need more connections the closer you get to the customer, and the more connections the more cost. That’s a problem given MPLS has high opex, he explains.

While Nortel has been pushing PBT as a way to simplify MPLS and strip away some of those costs, Cisco and Juniper Networks Inc. are emphasizing the shortcomings of PBT and T-MPLS. (Read “PBT, T-MPLS Try to ‘Transport’ Ethernet, MPLS.”)

Ian Hood, marketing manager for service provider solutions marketing at Cisco, says PBT is promising in its simplicity and reduced costs, but “our customers have asked us to deliver multiple services and there’s a lot more traffic in the network that is meshed than is point-to-point,” yet PBT is point-to-point. And when you look at cost and complexity, he says, addressing it via the control plane doesn’t solve the problem, it just moves it to a different location and makes it a proprietary solution.

“We see that MPLS lives in the core, as it always has, and a lot of our customers are driving us to deliver it also in the metro because, at the moment, there has not been a cost-effective and simple way to merge the services at Layer 1, Layer 2 and Layer 3 yet,” Hood adds. “MPLS is still the most mature, most scalable way to do this at this point. So we’re still very much behind having intelligence at the edge because of the services that are now mesh-like — video and voice over IP — that need multicast. Point-to-point technologies like PBT and T-MPLS don’t answer that question.”

Meanwhile, BT and Nortel are being joined on the PBT bandwagon by other vendors such as ADVA Optical Networking and World Wide Packets. (Read “BT Taps ADVA for 21CN Termination Equipment” and “World Wide Packets Embraces PBT.”)

Fred Ellefson, vice president of Etherjack Alliances for ADVA, says the company offers a PBT solution, but is not tying its wagon exclusively to that technology. While BT, an ADVA customer, is a great endorsement for PBT, other customers are going down other paths. “The big question mark for everybody is, as you scale, do you bring MPLS all the way to the edge, or do you use one of these newer technologies like PBT or T-MPLS,” he says. From our perspective, our product will support both those evolutions. We have customers pulling us in both directions.”

ADVA Optical Networking www.advaoptical.com
BT www.bt.com
Cisco Systems Inc. www.cisco.com
Frost & Sullivan www.frost.com
Juniper Networks Inc. www.juniper.com
Nortel Networks www.nortel.com
World Wide Packets www.worldwidepackets.com

Share this article: Email, Slashdot, Digg, Del.icio.us, Yahoo!MyWeb, Windows Live Favorites, Furl
Add this article feed to: RSS, My Yahoo, Newsgator, Bloglines