BT Group plc (NYSE: BT; London: BTA) is reconsidering its 21st Century Network (21CN) core network technology deployment plans, and may add a controversial new Ethernet approach to its IP/MPLS strategy, an executive from the British operator revealed today. (See BT Closes 21CN Deals, Touts IPTV.)

Speaking at the Carrier Ethernet World Congress in Madrid, Tim Hubbard, head of 21CN solutions strategy at BT, said the carrier is planning to use Provider Backbone Transport (PBT), a new flavor of Ethernet being heavily promoted by BT in league with Nortel Networks Ltd. , as a backhaul transport technology between its access nodes and metro nodes.

That will come as no surprise, as BT and Nortel have been jointly presenting PBT to the telecom standards bodies, and the carrier has been vocal about its support for the technology. (See BT Likes Nortel's New Ethernet Flavor.)

PBT, in a nutshell, strips out some of the complexity of Ethernet and enables service providers to create a managed, traceable point-to-point Ethernet tunnel across a network that provides SDH-like performance, so making Ethernet more manageable and scaleable.

This is achieved, using existing Ethernet switches, by turning off certain Ethernet functions, such as Spanning Tree Protocol and MAC learning, and deploying Ethernet OAM (operations, administration, maintenance) functions that are currently going through the Institute of Electrical and Electronics Engineers Inc. (IEEE) and International Telecommunication Union (ITU) standards bodies. (See Nortel Launches PBT.)

But Hubbard revealed that BT is considering using PBT in a broader context. He said the carrier had issued an Ethernet ITT (invitation to tender) -- a.k.a. an RFP (request for proposal) -- earlier this year because BT "is asking itself, do we need a complete IP/MPLS core? Since the arrival of technologies such as PBT, it is possible to use that in the core and reduce" the reliance on IP/MPLS. (See BT Issues 21CN Ethernet RFP.)

Such a move is still feasible for BT's 21CN buildout, stated Hubbard, as "our 21CN IP/MPLS core network is not fully deployed yet -- our options are still open."

One of those options is to "extend the Ethernet backhaul to give a single Ethernet infrastructure layer end-to-end," a move that would have significant implications for the 21CN core capital expenditure, said Hubbard.

And, presumably, be not such great news for BT's two 21CN core router vendor suppliers, Cisco Systems Inc. (Nasdaq: CSCO) and Lucent Technologies Inc. (NYSE: LU), which is providing Juniper Networks Inc. (NYSE: JNPR) gear. (See Lucent, Juniper to Supply BT 21CN and Cisco Picked for BT's 21CN.)

Such a move would also send shock waves around the global carrier community, which has, to date, reached a consensus that the world's next-generation networks will have IP/MPLS cores at their hearts.

But BT's motivation is not just the potential capex saving. Hubbard says there are some utility companies that require absolute iron-cast SLAs for alarms, such as the electricity and nuclear power generating companies, and the carrier is looking to pin down its guaranteed response times so that, for example, there is no chance of an alarm delay that could result in an explosion at an electricity generator plant. "There could be lives on the line over this," he stated.

Hubbard says vendor submissions for the Ethernet ITT are in and are being assessed. Vendors here in Madrid see Nortel as the obvious vendor to benefit from any PBT deployment.

The response here from delegates to BT's 21CN core rethink was one of surprise, and, from the MPLS supporters, incredulity. The PBT versus MPLS debate looks as if it will dominate proceedings during the Ethernet event. "I sense that the MPLS community is a bit troubled by PBT," stated Mark Lum, an independent consultant who was chairing the event's proceedings.

And the MPLS community could be in for more strife, as it seems BT is not the only Tier 1 carrier cozying up to PBT's charms. In presentations made at the Broadband World Forum Americas event in Vancouver last week, Verizon Communications Inc. (NYSE: VZ) and BCE Inc. (Bell Canada) (NYSE/Toronto: BCE) both expressed an interest in PBT in presentations made to delegates.

No surprise, then, that Nortel is not the only vendor here in Madrid espousing the benefits of PBT. Siemens Communications Group talked up the technology during a presentation today; packet switching vendor Tpack A/S has issued a white paper on the technology; and Extreme Networks Inc. (Nasdaq: EXTR) has expressed vocal support.

— Ray Le Maistre, International News Editor, Light Reading