What: Provider backbone transport (PBT) technology, also known as provider backbone bridging-traffic engineering (PBB-TE)
Why you should care: PBT is a Layer 2 switching scheme that makes Carrier Ethernet cheaper by removing Spanning Tree, media access control address-flooding and other features more pertinent to enterprise Ethernet than Carrier Ethernet. The result also simplifies point-to-point connections.
Who's using it? BT has been the carrier most vocally supportive of PBT, and Nortel Networks was perhaps the earliest vendor behind the technology. Together, they proposed PBB-TE standardization at the IEEE, which is ongoing. Several other vendors also now support the technology, and many carriers are interested.
Primary challenge it faces: Carrier Ethernet already has become a success using Layer 3 transport-multiprotocol label switching (T-MPLS). PBT may need to displace T-MPLS to fully succeed, though some people in the industry believe PBT and T-MPLS both will be used often in the same networks.
This story [1] from Network World last June highlights points in the PBT vs. T-MPLS debate.
Links:
[1] http://www.networkworld.com/supp/2007/ndc4/061807-tmpls-vs-pbt.html