Cisco OSM-12CT3/T1 - Optical Services Module Multiplexor Installationsanleitung PDF herunterladen (Seite 35)

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Cisco 7600 Series Internet Router Module Installation Guide

78-12798-07

Chapter 1 Product Overview

Power Management and Environmental Monitoring

For detailed information on power management and environmental monitoring,

refer to the Cisco 7600 Series Internet Router Software Configuration Guide.

OSM Technology Overview

This section provides an overview of SONET/SDH and ATM:

• SONET/SDH Overview, page 1-35

• ATM Overview, page 1-36

SONET/SDH Overview

The Packet over SONET (POS) specification defines the use of PPP encapsulation

over SONET/Synchronous Digital Hierarchy (SDH) links. SONET is an ANSI

standard (T1.1051988) for optical digital transmission at hierarchical rates from

51.840 Mbps (STS-1) to 2.5 Gbps (STS-48) and greater. SDH is the international

standard for optical digital transmission at hierarchical rates from 155.520 Mbps

(STM-1) to 2.5 Gbps (STM-16) and greater.

Because a SONET/SDH link is considered to be a point-to-point circuit, PPP is

well suited for use over these links. PPP was designed as a standard method of

communicating over point-to-point links.

SONET is an octet-synchronous multiplex scheme that defines a family of

standard rates and formats. The basic rate for POS is STS-3c/STM-1, which is

155.520 Mbps. The available information bandwidth is 149.760 Mbps, which is

the STS-3c/STM-1 Synchronous Payload Envelope (SPE), the payload portion of

the SONET frame into which the octet-oriented user data is mapped. (Octet

boundaries are aligned with the SPE octet boundaries.)

The International Telecommunications Union Telecommunication Sector (ITU-T)

defines a series of SDH transmission rates beginning at 155.520 Mbps as follows:

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Cisco OSM-12CT3/T1 - Optical Services Module Multiplexor Installationsanleitung Seite 35