Carriers Speak Out About PBT in New Synergy Report

Nearly one quarter of operators said they were considering deploying provider backbone transport (PBT) in their networks, according to Synergy Research Group, which published today the first carrier survey on PBT, the emerging and debated methodology for providing point-to-point Ethernet in a transport network.

With feedback from 37 providers worldwide, Synergy Research Group compiled a snapshot of carrier’s current interest and concerns about PBT, which is now being standardized by the IEEE as provider backbone bridging – traffic engineering (PBB-TE).

PBT provides Ethernet transport using point-to-point tunneling technology that adds determinism to Ethernet, enabling service providers to specify the path that an Ethernet service should take across the network with SONET-like reliability and management capabilities. By enabling PBB, service providers can define PBT tunnels and run Ethernet or other traffic types over it.

Aside from BT, which is widely known to be backing the technology for use in its 21st Century Network, six other carriers among those surveyed are evaluating PBT in trials, said Ray Mota, chief strategist for Synergy Research Group and the report’s author. Unlike VPLS which took more than three years to gain acceptance, he said, “PBT has a head start” with such high-profile support.

Mota said 22 percent of respondents – executives from carrier networking and transport groups – said they were considering deploying PBT in their networks. Interestingly, this number jumps to 35 percent when looking only at carrier transport executives alone, he said.

This dichotomy is not too surprising considering that PBT is designed to make Ethernet more deterministic like SONET/SDH, which carrier transport groups are accustomed to, said Mota. However, he added, the high number – one-third – expressing interest is surprising given that the still early days for PBT.

Indeed, the greatest concern about PBT expressed by the surveyed operators is that it is not yet standardized or interoperable. Eighty-five percent of respondents cited this drawback.

This also is a common citation among PBT opponents, which generally are backers of end-to-end IP/MPLS. IP/MPLS is resilient and fault tolerant and emulates some properties of a circuit-switched network over a packet-switched network.

For all its virtues, IP/MPLS has not won over end users, Mota said, relaying carriers’ unmet projections for converting ATM and frame relay customers. Customers’ “perceived service experience” is that the MPLS cloud is not as reliable at the point-to-point connection. “Some customers still want that point-to-point experience,” Mota said.

While this may be a driver for some service providers to consider a deterministic Ethernet option, most are lured by its supposed economic advantages. “Carriers do not expect PBT to be the answer to all of their network problems or convergence issues, but they do expect to test it in some part of the network that are currently point-to-point and conduct an assessment on the ROI,” the report stated.

However, Mota said, so far he has no concrete proof from service providers that it is less expensive. “There isn’t a lot to prove it; it’s theoretical,” said Mota, noting VPLS vendors are squeezing margins to meet PBT price points, so the capex differential may disappear leaving only an opex decrease. “I think the capex is a wash. We need to drill down into the operations and see if this is really helping the opex. The SONET transport guys may be less expensive [than the MPLS networking technicians], but are they able to run the network better when it’s centralized.”

In addition, service providers now have to contend with T-MPLS, which is a stripped down version of MPLS for the transport network.

Synergy Research Group’s report, “PBT and Metro Network Transport Analysis,” discusses drivers for Carrier Ethernet transport; PBT technology, functions and misconceptions; cumulative answers to the service provider survey; and recommendations to service providers, vendors and equity analysts. The report is available for $3,995 and includes a one-hour analyst Web presentation with additional exhibits not included in the written study.

Synergy Research Group www.srgresearch.com

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