1 © 2003, Cisco Systems, Inc. All rights reserved. CCNA 4 v3.0 Module 2 WAN Technologies Cisco Networking Academy.

1© 2003, Cisco Systems, Inc. All rights reserved.

CCNA 4 v3.0 Module 2WAN Technologies

Cisco Networking Academy


Objectives

• WAN Technologies Overview

• WAN Technologies

• WAN Design


WAN Technology

(Phone Company)“Last Mile”


WAN Service Providers

POP

T1


WAN Authorities

• (ITU-T), formerly the (CCITT)

• (ISO) International Organization for Standardization

• (IETF) Internet Engineering Task Force

• (EIA) Electronic Industries Association


Physical Layer: WANs

Clock Signal

Interface Types


WAN Line Types and Bandwidth


WAN Devices

(Access Server)

(Console Server)


CSU/DSU

Channel Service Unit/ Digital Service Unit

T1

External CSU/DSU


Modem Transmission


Circuit Switching

Circuit is created for duration of the calland torn down after call is over.


Packet Switching


WAN Encapsulation – Layer 2


WAN Data-Link Protocols – Layer 2


HDLC

High-Level Data Link Control (HDLC) - An ISO standard. HDLC might not be compatible between different vendors because of the way each vendor has chosen to implement it. HDLC supports both point-to-point and multipoint configurations.Cisco uses its own proprietary implementation of HDLC as the default encapsulation on all serial interfaces.– HDLC was first developed by IBM


Integrated Services Digital Network (ISDN)

Basic Rate Interface

Primary Rate Interface


ISDN

Integrated Services Digital Network (ISDN)

• A set of digital services that transmits voice and data over existing phone lines.

• ISDN was the phone companies attempt at creating an all digital phone system.

• ISDN is still popular for dedicated video, voice and remote sites where DSL is not available.


ISDN

2503 or 2513

2600 w/ WIC1-BU


Leased Line

• Leased lines are not only used to provide direct point-to-point connections between Enterprise LANS, they can also be used to connect individual branches to a packet switched network.


WAN with X.25

• X.25 provides a low bit rate, shared-variable capacity that may either be switched (SVC) or permanent (PVC)

VC = Virtual Circuit


Frame Relay

Frame Relay - By using a simplified framing with no error correction mechanisms over high-quality digital facilities, Frame Relay can transmit data very rapidly, compared to these other WAN protocols.– Frame Relay depends on upper layer protocols

such as TCP to take care of lost data

Frame Relay is the successor to X.25 and is designed to run over high speed fiber as well as copper.


Frame Relay

• Most Frame Relay connections are based on PVCs rather than SVCs.

• It implements no error or flow control.

• Frame Relay provides permanent shared medium bandwidth connectivity that carries both voice and data traffic.


ATM

• Asynchronous Transfer Mode (ATM) is a technology capable of transferring voice, video, and data through private and public networks. It is built on a 53-byte cell based architecture rather than on a frame-based architecture.


Point-to-Point Protocol

Point-to-Point Protocol (PPP) - Described by RFC 1661, two standards developed by the IETF. PPP contains a protocol field to identify the network-layer protocol.

PPP allows for dynamic address allocation and authentication.– PAP – Password Authentication Protocol

– CHAP – Challenge Handshake Authentication Protocol


Broadband

• Broadband refers to a technique which uses multiple frequencies within the same physical medium to transmit data.

• Generally speaking, Broadband refers to cable modem and DSL modem technologies for the home user.


DSL

Do you get these download speeds???

Digital Subscriber Line (DSL) technology is a broadband technology that uses existing twisted-pair telephone lines to transport high-bandwidth data to service subscribers.


xDSL

• The term xDSL covers a number of similar yet competing forms of DSL technologies:

1. Asymmetric DSL (ADSL)

2. Symmetric DSL (SDSL)

3. High Bit Rate DSL (HDSL)

4. ISDN (like) DSL (IDSL)

5. Rate Adaptive DSL (RADSL)

6. Consumer DSL (CDSL), also called DSL-lite or G.lite


ADSL Technology


Cable Modem

• Enhanced Cable Modems enable two-way, high speed data transmissions using the same coaxial lines that transmit cable television.


Modern WAN


Star Topology – Hub and Spoke


Full-Mesh Topology


Partial-Mesh Topology


Three-Layer Design Model

• The links connecting the various sites in an area that provide access to the enterprise network are called the access links or access layer of the WAN.

• Traffic between areas is distributed by the distribution links, and is moved onto the core links for transfer to other regions, when necessary.


Internet for WAN Connectivity


One-Layer Hierarchy

1 © 2003, Cisco Systems, Inc. All rights reserved. CCNA 4 v3.0 Module 2 WAN Technologies Cisco Networking Academy.

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