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POINTER PROCESSING TECHNIQUE FOR SYNCHRONOUS OPTICAL NETWORKING (SONET) AND SYNCHRONOUS DIGITAL HIERARCHY (SDH) OVER PACKET SWITCH NETWORKS (PSN)

IP.com Disclosure Number: IPCOM000212603D
Publication Date: 2011-Nov-17

Publishing Venue

The IP.com Prior Art Database

Related People

Gilberto Loprieno: AUTHOR

Abstract

The techniques described herein allow for efficient synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) packets to be sent over a packet switch network (PSN) without pointer transport. Specifically, these techniques allow pointer values to be regenerated at an egress node of a PSN with minimal packet overhead. The ingress node receives frames (e.g., synchronous transport modules (STMs)) and removes the transport overhead from these frames. The ingress mode identifies a particular byte position and marks the packet as containing the byte position. The ingress mode then adds minimum overhead for operation, administration and maintenance information. The egress node receives the frame and checks the packet length to determine the presence of the particular byte position. The egress node decodes the payload of the frame and determines a pointer value associated with the payload.

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  POINTER PROCESSING TECHNIQUE FOR SYNCHRONOUS OPTICAL NETWORKING (SONET) AND SYNCHRONOUS DIGITAL HIERARCHY (SDH) OVER PACKET SWITCH NETWORKS (PSN)

  AUTHORS: Gilberto Loprieno Giacomo Losio

CISCO SYSTEMS, INC.

                  ABSTRACT
The techniques described herein allow for efficient synchronous optical

networking (SONET) and synchronous digital hierarchy (SDH) packets to be sent over a packet switch network (PSN) without pointer transport. Specifically, these techniques allow pointer values to be regenerated at an egress node of a PSN with minimal packet overhead. The ingress node receives frames (e.g., synchronous transport modules (STMs)) and removes the transport overhead from these frames. The ingress mode identifies a particular byte position and marks the packet as containing the byte position. The ingress mode then adds minimum overhead for operation, administration and maintenance information. The egress node receives the frame and checks the packet length to determine the presence of the particular byte position. The egress node decodes the payload of the frame and determines a pointer value associated with the payload.

             DETAILED DESCRIPTION
The techniques described herein describe an approach to regenerate pointer values

at the egress node of a packet switched network (PSN). For example, the techniques described herein enable mapping of SONET/SDH into a PSN. The techniques also describe transporting payloads without overhead in packet switched networks. Since legacy synchronous optical networking (SONET) and synchronous digital hierarchies (SDH) are widely diffused but application of PSN for transport is growing, the problem of transporting SONET and SDH over a PSN is becoming to be very critical. One of the

Copyright 2011 Cisco Systems, Inc. 1


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major problems arises with respect to treatment of SONET/SDH pointers. The pointer management techniques described herein enable PSNs to transport SONET/SDH payloads over packets. In one example, a synchronous transport module (STM) is mapped over an Ethernet payload. The STM is a framed structured based on overhead area and payload. Overhead bytes are used for operation and maintenance and usually are terminated at the edge of the SONET/SDH layer. H1/H2 bytes are called VC-4/AU-4 pointers, and they transport the pointer value to POH "J1" bytes because after this byte starts the payload area transported by the frame.

    The STM payload is transported without the overhead and also without the H1/H2 pointers. At the ingress side, the received frame will interpret the pointer and will identify the byte in the payload (e.g., "J1" in FIG. 1). The byte will be marked and will be easily identified at an egress node, which allows for pointer recalculation.

    In general, the payload of the incoming TDM frame (e.g., STM packet) will be encoded in the payload of the Ethernet packet. Minimal information will be added to the TDM frame, which may include information pertaining to the packet order, pack...