216APPENDIX B: PATHBUILDER S330/S310 MODULE AND APPLICATION OVERVIEW

DXI protocol defines an open interface between the router and the Data Service

Unit. The Data Service Unit off-loads cell encapsulation services from the Brouter.

This will allow your current brouter to support ATM, simply by supporting V.35 and

High-level Data Link Control (HDLC).

The DXI protocol itself is based on HDLC and provides the mapping within the

HDLC frame to place the router data on an appropriate VC. (See Figure 156.)

Figure 156 DXI Protocol Enabling Transmission Between ATM Network and DXI Device

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Synchronous

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

V.35

 

 

 

 

 

IP

 

 

 

 

 

RS 449/422, X.21, RS-530

 

 

 

Internet Router

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DXI

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DXI

 

 

Protocol

 

 

 

DXI

 

 

 

 

DXI Link

 

DXI Link

 

 

 

 

Transport

DS1

 

Transport

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Router/DXI

 

 

 

AAL 5

 

 

 

 

 

 

 

 

 

 

 

 

 

ATM

 

 

 

 

 

 

 

 

 

ATM Cell

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Path Layer

 

 

 

 

 

 

 

 

 

 

 

Line Layer

 

 

 

 

 

 

 

 

 

 

 

Section Layer

 

SONET

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Photonic Layer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ATM/DSU/SONET

 

 

 

 

 

 

 

 

 

 

 

 

The ATM DXI Specification defines 3 different modes (1a, 1b, and 2) of connections. This software release supports Mode 1a, which includes the following features:

Up to 1023 virtual connections

Uses AAL5

Maximum DTE SDU size: 9232 bytes

Uses 16-bit FCS

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3Com S330 manual Aal