Edge networking vendor Hammerhead Systems today introduced a software-based solution for interworking provider backbone transport (PBT) technology with its sometimes rival, multiprotocol label-switching (MPLS).

PBT, a point-to-point layer-two tunneling technology, has been proposed in recent months as a cheaper alternative to layer-three-based MPLS in metro networks. Debate over the merits of each technology has led many to question where PBT rightly ends and MPLS begins. Nortel Networks, one of the earliest proponents of PBT, has argued that the two can complement each other well if PBT is used in the metro and MPLS is used in core networks.

Hammerhead has proposed a way to allow carriers to use both PBT and MPLS together: A software upgrade to the vendor’s existing HSX 6000 edge aggregation switch will function as a PBT gateway.

“As [early adopters] build out PBT in their networks, they’ll have islands of it,” said Rob Keil, Hammerhead’s founder and vice president of marketing. “Those islands aren’t connected to the rest of the MPLS network, which doesn’t speak PBT.”

A “layer 2.5” platform, as Hammerhead calls it, the 6000 already includes a service interworking engine that can be used to aggregate a variety of attachment circuits such as pseudowires, virtual local access networks, virtual private line service and frame relay. New software, available on the 6000 in the second half of this year, will add PBT tunnels as yet another attachment circuit option.

Though the 6000 is sold by Fujitsu Network Communications as the Flashwave 6400 through a partnership the two vendors formed in 2004, the new PBT gateway software will be sold only directly by Hammerhead, the company said.