Startups Explore Realm Between Edge And Core

CHICAGO — The no man's land where edge access meets core transport is fertile ground for ideas on how to get data-aware Sonet, Gigabit Ethernet and multiprotocol label-switched (MPLS) traffic flows to work together. Scores of OEMs and startups at Supercomm 2004 this week will be busy seeding this field in an attempt to lower the cost of the edge boxes while enhancing their service capabilities.

To enable this new generation of converged networks and services, equipment vendors are relying on such maturing encapsulation techniques as generic framing procedure (GFP) and virtual concatenation. They are also incorporating newer concepts that stretch MPLS from a core-networking to a metro edge-based technology.

This is hardly a safe haven for startups, but Mangrove Systems, Turin Networks and Mahi Networks are among the young companies combining elements of fiber transport systems and multiservice provisioning platforms for this murky realm between edge and core.

"The maturation of Sonet data encapsulation methods like GFP and virtual concatenation really made a difference," said Jonathan Reeves, founder of Mangrove Systems Inc. Mangrove had been dropping hints in recent months about its interest in GFP over passive optical, in pseudo wire emulation of services over Internet Protocol (IP) flows and in GFP as a road to the long-awaited generalized MPLS (G-MPLS). All of these goals center on a metropolitan redefinition of MPLS, which is commonly seen as a core-related switching standard for IP flows, Reeves said. Mangrove's larger Barracuda and smaller Piranha platforms implement what the company calls MetroMPLS, extending the utility of the switching to access systems based on either Sonet or Ethernet.

This implies the end of segregation between multiservice Layer 2 switching functions and transport functions at Layers 0 and 2, Reeves said. That proposal will find little dissent at Turin Networks Inc. or Mahi Networks Inc., which claim their new expanded systems must span switching and transport to be effective.All Mangrove systems have hybrid packet and TDM switching fabrics. The smallest Piranha 100 is a 1U box with Gigabit Ethernet or 155-Mbit Sonet uplinks. The multislotted Piranha 600 adds NEBS hardening and full 1+1 redundancy. Barracuda is the central-office chassis aggregating DS-3, Sonet rates from OC-3 to OC-192, and Ethernet at 1- and 10-Gbit rates. The secret sauce of the Mangrove engine is a double layer of encapsulation using PWE3 and GFP.

Turin, an early advocate of both data-aware Sonet and G-MPLS, needed a multiservice "pizza box" at the edge to take on Ethernet-centric access companies looking to displace TDM and ATM multiplexers. Director of marketing Kevin Wade said the edge was converging on a simple platform priced at $5,000 to $10,000, but that carriers needed better support for GFP and virtual concatenation. The TraverseEdge 100 Sonet add-drop multiplexer (ADM) also integrates Layer 2 Ethernet switching.

In theory, the system would compete with edge boxes, but the arrival of circuit emulators from the packet world will complicate matters a bit. "We see vendors like Overture, Covaro and Luminous trying to aggregate the various services through circuit emulation," Wade said. "But it's not certain they'll end up being a direct competition at the edge."

Mahi, for its part, is melding its original multiservice provisioning platform with a reconfigurable optical ADM from the newly acquired Photuris. Mahi CEO Chris Rust said the combination of the Mahi Mi7 and the Photuris Vx7 allowed the hybrid transport/switching architecture to scale to "hundreds of rings with tens of subtended add-drop multiplexers."

Mahi says its solution spans Layers 0 to 2+, incorporating TDM grooming and packet switching without attempting to move to true Layer 3 routing. The Mi7 and Vx7 are augmented with special line cards and software to serve specific dedicated applications. The Mi7 alone has been optimized for metro Ethernet transport, broadband convergence gateways and edge packet aggregation. By adding the Vx7, Mahi can enhance its Sonet ring aggregation as well as offer an extended service reach over the very long haul.0