PBB-TE: Hot No More

It’s not exactly a hot news flash that PBT, a technology once championed by BT and its supplier Nortel (and many other, smaller vendors that followed in its footsteps), has lost its luster in recent months. But Lightstorm Networks, which today introduced a new Ethernet chip set, drove home that point, saying PBB has come into favor while PBT (and the standardized version of it, known as PBB-TE) has fallen out.

PBB and PBB-TE/PBT, as well as VPLS, all have been positioned as ways to help service providers better scale and manage their Ethernet networks.

However, PBT/PBB-TE took a major hit when BT this June distanced itself from the technology it had once helped Nortel promote. Around the same time, NXTcomm, KPN and Verizon announced plans to use PBB.

To help you wade through all these acronyms, here’s a guide to what’s what in the alphabet soup surrounding Carrier Ethernet:

• MPLS, which stands for Multiprotocol Label Switching, creates label-switched paths for IP flows and can handle multiple protocols. It is a widely used technology in carrier backbone networks today and many of the large router companies have promoted it as a solution to address transport at the network’s edge as well.
• MPLS-TP is a new, joint effort by the IETF and ITU-T that aims to combine their separate MPLS and T-MPLS efforts around Ethernet transport. MPLS-TP, around which drafts are expected by the end of the year, addresses such issues as control plane, network management, resiliency and protection.
• PBB, or Provider Backbone Bridge, is a technology that can help carriers scale their networks by offering a solution for MAC addressing.
• PBB-TE is a PBB-based solution optimized for point-to-point connections. It brings with it SONET-like 50msec resiliency and traffic engineering (thus the –TE) to edge networks.
• PBT is Nortel’s proprietary version of PBB-TE.
• PLSB, which stands for Provider Link State Bridging, addresses efficient video distribution by combining the multicast/unicast capable per switch shortest path spanning tree, with PBT paths segments to allow full multicast and unicast data from all Backbone Bridges.
• T-MPLS was an ITU-T effort to add determinism to Ethernet. When PBT/PBB-TE first surfaced, T-MPLS was seen as a possible alternative. But T-MPLS seemed to fade into the woodwork after the ITU-T and IETF began to head in different directions on this front.
• VPLS, or Virtual Private LAN Service, describes an Ethernet-based service delivering any-to-any virtual private network connections over IP/MPLS networks.

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