4000 Router Series Interface Configuration Guide

Configuring POS interfaces

The following matrix shows the POS interface feature and router compatibility:

Feature MSR2000 MSR3000 MSR4000

POS interface No Yes Yes

Overview

SONET

Synchronous Optical Network (SONET) adopts optical transmission. It is a synchronous transmission

system defined by the ANSI and is an international standard transmission protocol.

SDH

ITU-T Synchronous Digital Hierarchy (SDH) uses a SONET rate subset. SDH adopts synchronous

multiplexing and allows for flexible mapping structure. It can add or drop low-speed tributary signals to

or from SDH signals without a large amount of multiplexing/demultiplexing devices. This reduces signal

attenuation and decreases device investments.

POS

Packet over SONET/SDH (POS) is a technology widely used on WAN and MAN. It supports data

packets such as IP packets.

POS maps length-variable packets directly to SONET synchronous payloads and uses the SONET

physical layer transmission standard. It offers high-speed, reliable, and point-to-point data connectivity.

The POS interfaces on your device support PPP and HDLC at the data link layer and IP at the network

layer. Depending on your device model, the transmission rate of POS interfaces can be STM-1, STM-4,

and STM-16. The rate of a level is four times the nearest lower level.

Configuring a POS interface or POS subinterface

Configuration prerequisites

• Before you configure the link layer and network layer protocols on a POS interface, you must

configure its physical parameters.

• (Optional.) Configure the interface backup parameters to have the interface participate in backup.

• (Optional.) Configure packet filtering rules to set up a firewall on the interface.