qaSfdhjkllkjhgfdsaasdfghjkl;lkjhgfdsaq2wsxgtgb k,m.;lifdsa, Study Guides, Projects, Research of Economics

Download qaSfdhjkllkjhgfdsaasdfghjkl;lkjhgfdsaq2wsxgtgb k,m.;lifdsa and more Study Guides, Projects, Research Economics in PDF only on Docsity!

Chapter 18

Virtual-Circuit Networks:

Frame Relay and ATM

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

181181 FRAME RELAYFRAME RELAY

Frame Relay is a virtual-circuit wide-area network Frame Relay is a virtual-circuit wide-area network

that was designed in response to demands for a new that was designed in response to demands for a new

type of WAN in the late 1980s and early 1990s. type of WAN in the late 1980s and early 1990s.

Architecture Frame Relay Layers Extended Address FRADs VOFR LMI

Topics discussed in this section: Topics discussed in this section:

VCIs in Frame Relay are called DLCIs.

Note

Figure 18.2 Frame Relay layers

Figure 18.3 Frame Relay frame

Frame Relay does not provide flow or

error control; they must be provided

by the upper-layer protocols.

Note

Figure 18.5 FRAD

182182 ATMATM

Asynchronous Transfer Mode (ATM) is the Asynchronous Transfer Mode (ATM) is the cell relaycell relay

protocol designed by the ATM Forum and adopted by protocol designed by the ATM Forum and adopted by

the ITU-T. the ITU-T.

Design Goals Problems Architecture Switching ATM Layers

Topics discussed in this section: Topics discussed in this section:

A cell network uses the cell as the basic

unit of data exchange.

A cell is defined as a small, fixed-size

block of information.

Note

Figure 18.7 Multiplexing using cells

Figure 18.9 Architecture of an ATM network

Figure 18.10 TP, VPs, and VCs

Note that a virtual connection is defined

by a pair of numbers:

the VPI and the VCI.

Note

Figure 18.12 Connection identifiers