German incumbent carrier Deutsche Telekom AG (NYSE: DT) is checking out new Ethernet technology PBT (Provider Backbone Transport) in a field trial it's conducting with Nokia Networks . (See NSN Shows Off PBT.)

The two companies teamed up at this week's ECOC (European Conference on Optical Communication) in Berlin to present details of how PBT -- a.k.a. PBB-TE (Provider Backbone Bridging - Traffic Engineering) -- and WDM configurations can be deployed as an alternative to IP router-based deployments for metro Ethernet transport.

The carrier declined to comment further on the trial, which is being undertaken by DT's T-Systems International GmbH division as part of a broader research project called EIBONE. (See Siemens Presents on Planning Metro Nets.)

News of DT's interest in PBT, even though it's clearly at an early, exploratory stage, is another sign that major carriers are taking the new flavor of Ethernet seriously. PBT's supporters say its deterministic, SDH-like features, and the claims of lower opex compared with MPLS-based deployments, make the new flavor of Ethernet appealing to carriers' operations teams. (See PBT: New Kid on the Metro Block, Nortel, Siemens Win PBT Deals at BT, and BT Pressures Vendors Over PBT.)

So what has Nokia Siemens -- one of PBT's earliest vendor champions alongside lead tub-thumper Nortel Networks Ltd. -- been showing off in Berlin? (See NSN Touts PBT.)

The vendor emails us that the field trial shows two alternative options for transporting Ethernet services in metro networks: the first using the vendor's PBT-enabled hiD6650 and hiD6670 carrier Ethernet switches with "protection in the Ethernet layer"; and the second using Nokia Siemens's hiT7300 WDM platform with ROADM and various muxponders, where the Ethernet traffic is transported "transparently in DWDM using optical protection."

Nokia Siemens points out, though, that the trial is not being conducted on an exclusive basis and that it's not part of a commercial deal between the vendor and carrier.

Separately, Nortel also claims to be working at some level with the German incumbent on carrier Ethernet advances. When asked whether the Canadian vendor is working with DT on PBT developments, Nortel's president of the EMEA region, Darryl Edwards, said his company is "engaged with all the major carriers in Europe" on PBT.

Nokia Siemens Networks and Nortel are just two of the vendors aiming to benefit from increasing carrier interest in PBT. (See Nortel Lands More PBT Action, Ixia Digs on Wireless, PBT , PBT Parties On, Soapstone Intros PNC for PBT, Nortel Pushes PBT Pact, and Huawei Joins PBT Fan Club.)

— Ray Le Maistre, International News Editor, Light Reading