An Update on the Move to Make Ethernet Carrier-Class

At the risk of mixing metaphors, industry efforts to make Ethernet carrier-class seem to be a combination of alphabet soup and musical chairs.

To the first point, a variety of technologies such as PBB, PBB-TE, PBT and VPLS all have been positioned as ways to help service providers better scale and manage their Ethernet networks. To the second point, various service providers and vendors are committing to — and at least in one case backing away from — these technologies.

PBB — Controlling the MAC Attack

The week prior to NXTcomm, KPN and Verizon announced plans to use PBB. That same week, Fujitsu Network Communications Inc. formally pledged its support for PBB-TE. Around the same time, BT indicated it’s pulling away from PBB-TE, at least for the time being.

KPN is the first announced customer of a new Alcatel-Lucent Carrier Ethernet solution employing both PBB and VPLS. Lindsay Newell, Alcatel-Lucent vice president of marketing, said the solution — which is a software addition to his company’s 7750 SR, 7710 SR and 7450 ESS IP/MPLS service router products — is an industry first and will help service providers like KPN better scale their networks.

Service providers already have widely deployed VPLS, which has worked well for the past several years. But recently, these VPLS networks have grown so large that they’re running into some scaling issues, especially in the area of MAC addressing. While MPLS/VPLS is good at scaling the control plane to enable large networks to be built, PBB helps out by aggregating end user MAC addresses so the core network is not hit with what Newell termed a “MAC explosion,” which can adversely affect core routers and make troubleshooting more difficult.

There are two key carrier applications for this PBB/VPLS solution, Newell said. The first, which is how KPN is using it, allows carriers with VPNs in the metro and VPLS networks at the national level to use PBB/VPLS in their metro networks so MAC addresses are kept at the edge and don’t move into the core. The second application is for service providers, like some large North American carriers, that have built switched Ethernet in metro areas but now want to interconnect those areas to deliver consistent, nationwide Ethernet services.

Speaking of large North America service providers, Verizon Telecom in mid-June also committed to use PBB through a deal with Nortel based on the vendor’s Metro Ethernet Routing Switch (MERS 8600).

Philippe Morin, president of metro Ethernet networks at Nortel, told xchange that (like Alcatel-Lucent customer KPN) Verizon also chose the PBB solution to help scale its Ethernet VPN services.

(Newell said Alcatel-Lucent, KPN and Verizon, along with BT, Extreme and France Telecom, are sponsoring IETF work to define VPLS extensions for PBB.)

PBB-TE Musical Chairs

Nick Del Regno, principle member of technical staff at Verizon Business recently told xchange that Verizon was not interested in PBT/PBB-TE, but might be interested in PBB, though only for very limited applications.

“We see benefits, we see merit in PBB, both within our traditional native Ethernet networks that are LATA-bound, so they’re fairly geographically constrained, as well, PBB may be a good tool to scale national and global VPLS networks,” Verizon’s Del Regno said.

But while Nortel has won the business of Verizon on the PBB front, it recently took a hit when BT — which with Nortel was the biggest booster of PBT — indicated it had cooled on PBT and would not be using the technology in the immediate future.

Wendy Sycamore, PR manager for BT Group Chief Technology Office, told xchange: “Next-generation Ethernet is at the heart of BT’s 21CN architecture and is a key service platform in its own right. Following a comprehensive internal review of the relative merits of PBB-TE and MPLS against our immediate customer requirements, BT has decided to focus its attention on MPLS.

“Our customers’ needs today are primarily for connectivity for applications like content distribution and corporate VPN services across multiple locations. These applications are best met today by MPLS,” said Sycamore, adding that BT will continue to actively assess the role PBT may have in BT’s 21CN architecture and related to Carrier Ethernet.

“BT is one customer,” commented Nortel’s Morin. “Obviously, we’re disappointed we couldn’t continue — in the short term anyway — deployment around our Carrier Ethernet deployment of PBT. But I think now with the [PBB] Verizon win and the fact that we have about 40 customers, we’re actually moving ahead and staying the course.”

And while PBT has been promoted by Nortel, Morin emphasized that this technology is just one part of the vendor’s Carrier Ethernet toolkit.

The Case for MPLS/VPLS

Still, the fact that BT has distanced itself from PBT seems to add weight to arguments from folks at Alcatel-Lucent, Cisco Systems Inc., Juniper Networks, Telco Systems and Verizon, among others, who have said they don’t see the need for PBT.

Verizon’s Del Regno this spring told xchange: “Currently we don’t really see a need for PBT, and we don’t have any plans to deploy PBT,” which he described as “a step backwards.”

“When we first looked at deploying Ethernet services, we did something very similar, but we did it with VLAN; it’s a nailed-up, hop-by-hop VLAN cross-connect, very similar to how frame relay was originally deployed and how ATM was deployed without PNNI,” said Del Regno. “PBT is a lot like that same type of approach, and with the promise that we might someday make it a control plane, and that ‘Oh, by the way, that control plane is probably going to be GMPLS.’”

Manu Kaycee, vice president of product technology and strategy at Telco Systems, said VPLS is a better approach than PBT to address Carrier Ethernet transport.

“[VPLS] is a hardened technology which has been proven for a number of years in existing deployments with large carriers worldwide, and it provides an extremely scalable way to provide Carrier Ethernet services on a worldwide basis,” Kaycee said. “One of the things people have done to scale VPLS is called H-VPLS, or hierarchical VPLS. So, with hierarchical VPLS at customer premises, you have [what is] much like the frame relay hub-and-spoke model.”

Nonetheless, PBT/PBB-TE technology continues to win converts.

As mentioned above, Fujitsu has publicly embraced PBB-TE technology. Sam Lisle, Fujitsu market development director, told xchange he thinks PBB-TE is “a very excellent solution” for simplifying aggregation and network management in metropolitan area networks.

PBB-TE is a good match for metro Ethernet applications given it dovetails with the circuit-based aggregation network operational model, which for service providers means the ability to preserve investment in transport operations staff training and existing OSS. It also simplifies software management and the protection architecture. It reduces the size and complexity of the routed network topology and the number of network layers, meaning there are, as a result, fewer layers to provision and troubleshoot. And it eliminates complex processor software, according to Fujitsu.

Responding to xchange’s question as to why Fujitsu is embracing PBB-TE around the same time BT, one of the key initial boosters of PBT/PBB-TE, is distancing itself from the technologies, Lisle responded that Fujitsu is promoting PBB-TE specifically for Ethernet in metro environments, not as an MPLS replacement for the core, an application for which some have suggested it might work.

“I think what you’re starting to see is carriers saying that for MPLS, it’s not a great fit, and PBT still looks interesting for Ethernet metro,” he said.

Fujitsu is using PBB-TE in its packet optical networking platform, the FLASHWAVE 9500, said Lisle. The company announced the FLASHWAVE 9500 last year just before NXTcomm. At the time, Fujitsu mentioned the solution does connection-oriented Ethernet, but didn’t specifically note it does so by employing PBB-TE, Lisle added. PBB-TE will be generally available in the FLASHWAVE 9500 starting early next year and will be available for customer trials by the end of the year. The company also plans to add PBB-TE support to its new FLASHWAVE CDS.

Programmable Ethernet

The different postures on Carrier Ethernet-related technologies like PBB and PBB-TE are simply indicators of the fluidity of the market, noted Ron Kline, research director of optical networks at consulting firm Ovum.

“It’s apparent that the industry is in a state of flux,” he told xchange. “And I’m not sure anyone is quite sure how it will shake out.”

But no matter, he added. There are a variety of companies, like EZchip Technologies and Xelerated, offering programmable chipsets that are field-upgradeable so virtually any technology can be added when needed, he said. Alcatel-Lucent and Nortel both told xchange they also offer homegrown software-upgradeable processors akin to what’s available from EZchip and Xelerated.

Because the Ethernet switch embedded in Xelerated’s chipset is programmable, carriers can go to market with pre-standard services and scale those services, making any needed tweaks to the gear later and without interrupting service, said Rod Kay, general manager for U.S. operations at Xelerated.

That addresses one aspect of flexibility around Carrier Ethernet, but another side of the issue has to do with the software stacks running on these chips, noted Koichi Narasaki, president and CEO of IP Infusion, which at NXTcomm came out with release 7.6 of the ZebOS Advanced Platform. The new version of this software, which IP Infusion sells both to telecom equipment manufacturers and direct to carriers, offers increased support for Carrier Ethernet through PBB that is able to scale to more than 16 million Ethernet service instances, support for key technologies required to transport IPv6 over existing IPv4 networks and more.

“We are perfectly NGN-ready for Carrier Ethernet solutions providers,” said Narasaki. “We can include any technology — PBB, PBB-TE, whatever.”

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