TECHNOLOGY

With key architectural innovations as the underpinnings of its implementation, Hammerhead's Layer 2.5 solution is uniquely capable of combining the best of Layer 3 application awareness and the best of Layer 2 economics, operations, and interworking in a single platform that will help accelerate a Service Provider’s move to Ethernet-based access over a converged MPLS core while preserving existing customer revenues, and leveraging the underlying SONET/SDH based transport infrastructure where practical.

Layer 2.5
A Layer 2.5 system provides emulation of multiple Layer 2 services across a common packet switched network (PSN). Service emulation requires the encapsulation of native data packets within a format applicable to the PSN. The Pseudowire Emulation Edge-to-Edge (PWE3) protocol is a group of standards used for encapsulating service-specific protocol data units (PDUs) — arriving at an ingress logical port — and then carrying them across a tunnel, managing their timing and order as well as any other aspects that are required (when entering or leaving the tunnel) to emulate the behavior and characteristics of the Layer 2 services as closely as possible. To provide this Layer 2.5 functionality, the HSX 6000 implements the Pseudowire protocol.

Aggregation Platform
The HSX 6000 is the leading Layer 2.5 aggregation edge switch that includes support for Dry Martini and Pseudowire across any infrastructure. Dynamic signaling protocols such as RSVP-TE (used for tunnel set up), OSPF-TE (used for routing the tunnels), and the label distribution protocol (LDP) (used for Pseudowire connection set up) are implemented through the HSX 6000 control and signaling plane, which allows set up and use of either MPLS LSPs or Pseudowire. Pseudowire is primarily intended to provide only the minimum functionality with the required degree of quality for the given service definition. Any switching function required is the responsibility of a Layer 3 device.