By Meghan Fuller
Meriton Networks (www.meriton.com) is the latest vendor to enter the Carrier Ethernet fray, though the company is quick to point out that its new strategy is based on Carrier Ethernet transport, not service delivery.
As defined by Meriton, Carrier Ethernet Transport or CET is an architectural approach for building a scalable transport infrastructure for supporting Ethernet-which Meriton chief operating officer Bill Gartner calls “the new currency of exchange in the network”-and the evolution to next-generation networks. The CET strategy integrates Ethernet tunneling functionality via Provider Backbone Transport (PBT) or transport multiprotocol label switching (T-MPLS) with intelligent WDM functionality.
With CET, says Gartner, “you have a very flexible optical layer that includes switching capabilities at the wavelength and subwavelength layers and you have just enough-and that’s a key point-just enough Layer 2 capabilities to be able to provide an end-to-end Ethernet service, but not burden the optical or the transport layer with a lot of the Ethernet Layer 2 functions,” he explains. “You can think of it as a transport problem.”
A transport problem, Gartner says, is determining how to get a service from point A to point B, while preserving a very clear distinction between the service layer and the transport layer-and this is precisely the problem Meriton claims to have solved with the CET strategy.
Because CET enables a separation of the service delivery architecture from the underlying transport architecture, the transport network is transparent for service creation and modification (e.g., adds, moves, and changes). In other words, the transport layer is responsible for transporting traffic from point A to point B; it provides end-to-end capabilities for Ethernet reminiscent of circuit-oriented capabilities of SONET/SDH.
The optical layer capabilities then include wavelength switching (any port to any port), subwavelength (typically Gigabit Ethernet, GbE) switching (any port to any port), and Carrier Ethernet tunnel switching (any port to any port). Again, just enough switching capability is embedded in the optical layer to eliminate all the interport handoffs between the service layer and the transport layer, says Gartner.
Say you have a handoff between the transport layer and the service layer, but where that handoff would occur, the service layer says, “‘That Ethernet is really directed downstream from where you just handed it off to me,’” explains Gartner. “If we could make that decision locally in the transport layer, we could eliminate a number of Ethernet interfaces on these boxes. We are more efficiently looking at the optical signals as they pass through the transport layer and saying, ‘If it’s not necessary for that signal to go up to the service layer so that it can be switched, we’re not going to send it up there.’”
Gartner believes the CET story will resonate with carriers because each eliminated Ethernet interface represents a cost point for the carrier. Moreover, he believes alternative architectures, including an Ethernet overlay model or IP over DWDM, struggle with scalability issues, cost issues, and especially with what he calls “organization alignment. They force the data organizations and the transport organizations to make peace with each other or give something up,” he says, “and that is politically difficult to do.”
Meriton’s rollout of CET capabilities will occur in two phases. Phase one will enable carriers to support high-density GbE networking within the metro using subwavelength switching and grooming of nine GbE streams onto a 10-Gbit/sec wavelength. Phase two will introduce support for Carrier Ethernet tunnel switching and aggregation for local handoff. The first Ethernet tunnel technology to be supported by Meriton will be PBT, which is currently undergoing ratification within the IEEE under the proposed name of Provider Backbone Bridging-Traffic Engineering (PBB-TE).
Meriton is collaborating with Danish company TPACK (www.tpack.com) to add PBT-based Carrier Ethernet tunnel switching to the 7200 Optical Switching Platform (OSP), Meriton’s 320-Gbit/sec integrated switching and transport system. Together, the companies are developing an Intelligent Ethernet Gateway (IEG) that will be an optional component of the 7200 OSP.
Gartner says he sees the initial take for the CET-enabled 7200 OSP outside North America, particularly in Europe where BT’s recent announcement in favor of PBT has shined a spotlight on the technology. However, the company will be marketing its new CET strategy worldwide.
Phases one and two of Meriton’s CET strategy will be available on the 7200 OSP in the second half of 2007.