Packet-over-SONET/SDH (POS) (from Cisco)

enables core routers to send native IP packets directly over SONET/SDH frames. POS provides lower packet overhead and lower cost per Mbit than any other data transport method.

These efficiencies, along with the increasing evolution of the optical network, enable POS to efficiently support increases in IP traffic over existing and new fiber networks. POS is a SONET/SDH compliant interface that supports SONET/SDH level alarm processing, performance monitoring, synchronization, and protection switching (through APS/MSP).

This support enables the 12000 Series GSR and 7500 Series platform to seamlessly interoperate with existing infrastructures and/or migrate slowly to packet based optical networks, thus eliminating the need for expensive “forklift” upgrades to existing equipment as demand for services escalates.

www.cisco.com/warp/public/cc/pd/rt/12000/tech/posdh_wp.htm

Thats half of the truth, the QoS is known as poor, ATM can do that much better but with some overhead. So its suggested for very good fiber connections.

We will do some extensive tests with our new hardware we did buy in Aug 2002. More will be here. soon