chapter 1 services in a converged wan

© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE I Chapter 6 1

Services in a Converged WAN

Accessing the WAN – Chapter 1

© 2006 Cisco Systems, Inc. All rights reserved. Cisco PublicITE 1 Chapter 6 2

Objectives Describe how the Cisco Enterprise Composite

Model (ECNM) provides integrated services over an Enterprise network.

Describe the key WAN technology concepts.

Identify the appropriate WAN technologies to use when matching ECNM best practices with typical enterprise requirements for WAN communications.


Wide Area NetworksWAN

A WAN is a data communications network that operates beyond the geographic scope of a LAN.

WAN allows the transmission of data across greater geographic distances

WANs use facilities provided by a service provider, or carrier.

WANs use serial connections.

LAN connects computers, peripherals, and other devices in a single building or other small

geographic area

An enterprise must subscribe to a WAN service provider to

use WAN carrier network services.


WAN’s – The need

Sharing of data

Organization to organization

Remote users

Over large distance

LAN – Falls short

Company Growth


Evolving Enterprise

Stages of business growth.


The Evolving Network Model


Describe How ECNM Provides Integrated Services over an Enterprise Network Problems with the Hierarchical Design Model that Cisco's

Enterprise Composite Model has been designed to address


Describe How ECNM Provides Integrated Services over an Enterprise Network Explain the purpose of Cisco Enterprise Architectures


Key WAN Technology Concepts

WAN functions in terms of the OSI Reference Model

The physical layer (OSI Layer 1) protocols describe how to provide electrical, mechanical, operational, and

functional connections to the services of a communications service provider.

The data link layer (OSI Layer 2) protocols define how data is encapsulated for transmission toward a remote

location and the mechanisms for transferring the resulting frames. A variety of different technologies are used, such as Frame Relay and ATM. Some of these

protocols use the same basic framing mechanism, High-Level Data Link Control (HDLC), an ISO standard,

or one of its subsets or variants.


Key WAN Technology Concepts WAN physical layer concepts for network and Internet

communications



•WAN physical-layer protocols describe how to provide electrical, mechanical, operational, and functional connections for WAN services.

• The WAN physical layer also describes the interface between the DTE and the DCE.



WAN data link layer protocols used in today’s Enterprise WAN networks

Data link layer protocols define how data is encapsulated for transmission to remote sites

and the mechanisms for transferring the resulting

frames.

ATM uses small fixed-size cells of 53 bytes (48 bytes for data),



Switching technologies used for WANs in an Enterprise setting

A circuit-switched network is one that establishes a dedicated circuit (or channel)

between nodes and terminals before the users may communicate.

PSTN and ISDN are two types of circuit-switching technology that may be used to implement a WAN in an enterprise setting.

Packet switching splits traffic data into packets that are routed over a shared network. Packet-switching networks do not require a circuit to be

established, and they allow many pairs of nodes to communicate over the same channel. Packets are

divided and sent through available connections.

There are two approaches to this link determination, connectionless or connection-

oriented.


Select the Appropriate WAN Technology to meet ECNM Requirements

List the various options for connecting subscribers to the WAN



Enterprises use leased line services to provide a WAN connection

Point-to-point lines are usually leased from a carrier and are called leased lines.



Circuit switching options available to provide a WAN connection



Packet switching options available to provide a WAN connection



List factors to consider when selecting a WAN connection


Summary

A WAN is defined asA data communications network that operates beyond the geographic scope of a LAN

WAN primarily operate on layer 1 & 2 of the OSI model

WAN technologies include–Leased line

–ISDN

–Frame relay

–X.25

–ATM


Summary Cisco Enterprise Architecture

–This is an expansion of the hierarchical model that further divides the enterprise network into

•Physical areas

•Logical areas

•Functional areas

Selecting the appropriate WAN technology requires considering some of the following:

–WAN’s purpose

–Geographic scope of WAN

–Traffic requirements

–If WAN uses a public or private infrastructure

chapter 1 services in a converged wan

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