High-speed core router networks are moving rapidly into the SDH/SONET speed stack to meet the huge demands of IP networking. Core routers are now designed to perate most efficiently over fibre, from OC-3/STM-1 (155Mbit/s) through to OC-192/STM-64 (10Gbit/s). As products, they are technically removed from the current and earlier lower-speed applications aimed primarily at HSSI and PDH Networking. As the world migrates to IP traffic, data is increasingly being transported using HDLC frames, e.g. PPP, and POS(Packet-over-Sonet/SDH).

The Metrodata PA1000 converts data from byte-oriented HDLC, as used on Packet over Sonet (POS) interfaces, to bit-oriented HDLC as found on HSSI interfaces.

PA1000: Packet over Sonet to HSSI Converter

The PA1000 serves two purposes:

• it enables connection between a Packet over Sonet (POS) based router and a HSSI based router
• it enables a Packet over Sonet based router to be connected to a satellite modem and to operate at data rates below 155 Mbps

The PA1000 provides a solution for satellite operators wishing to use high performance Packet over Sonet (POS) based routers for example, Juniper routers with their standard 155Mbit/s POS interfaces to connect to a
HSSI-based network without the need to use valuable chassis slots for low speed HSSI serial interfaces. The user thereby gains a migration path - to use the router on <=52Mbit/s initially, and later upgrade his access speed to full STM-1 155Mbit/s later, without any hardware change to the router. In addition, the PA1000 supports non-standard data rates and asymmetric operation, thus providing a flexible solution for the user.

The PA1000 rate-adapts by stripping flags out of the data stream and transporting only the actual packet data. It is transparent to packet payload and may operate with any protocol that both the Packet over Sonet (POS) and HSSI devices support, such as PPP and Frame Relay.

The PA1000 provides the system integrator with a simple, convenient and economic solution for the interconnection of modern high speed routers fitted with Packet over Sonet (POS) interfaces and older legacy routers with HSSI interfaces.