Packet Over Lightwave David H. Su High Speed Network Technologies Advanced Network Technologies Information Technology Laboratory

-2- Packet Over SONET What’s Wrong with SONET? Inflexibility in Bandwidth Granularity –Must be a fixed multiple of OC-1: OC-3 (155Mbps), OC-12 (622Mbps), … High Overhead –Minimum of 3% overhead for framing, status monitoring, and management. Synchronous Network –High precision clocks and clock distribution networks. Support for Rate > 10 Gbps

-3- Packet over Lightwave Functional Requirements Framing: frame recognition, protection, scrambling, scalability (cost). Management & Control: fault detection and recovery, provisioning. Transparency: support of old and new services. Quality of Services: support of differentiated services. Timing: support of legacy synchronous networks (clock distribution).

-4- Evaluation of Framing Protocols Performance Metrics –Mean time to frame, mean timer to synchronize, probability of loss of frame, probability of false frame, strength of scrambling and error protection. Potential Candidates –IETF POS - PPP(HDLC)/SONET. –Lucent Simple Data Link (SDL). –ITU-T Digital Wrapper. len crc payload flag payload w crc ovrhd payload fec

-5- Mean Time to Frame

-6- Probability of Loss of Frame

-7- Probability of False Frame