WXES2106Network Technology

Semester 1 2004/2005

Chapter 2

Networking Media

CCNA1: Module 3, 4 and 5

Contents

Introduction Copper Media Optical Media Wireless Media Cable Testing Cabling the LAN Cabling the WAN

Introduction

Proper selection of cabling is key to efficient network operation.

Copper cable is used in almost every LAN Optical fiber is the most frequently used medium for the

longer, high bandwidth, point-to-point transmissions required on LAN backbones and on WANs.

Different specifications for cable Speed of bit transmission (bps) Transmission type (Base or Broad) Maximum distance Example: 10BASE-T, 10BASE5, 10BASE2

Introduction

Copper Media

Coaxial Cable Longer distance Thicknet coaxial cable more expensive to install

Copper Media

Shielded twisted-pair cable (STP)

Screened UTP (ScTP)

Copper Media

UnShielded twisted-pair cable (STP) Easy to install and less expensive Type of connection: Straight through, Crossover,

Rollover

Copper Media

Straight through Crossover Rollover

Optical Media

Optical Media

Every fiber-optic cable used for networking consists of two glass fibers encased in separate sheaths.

One fiber carries transmitted data from device A to device B. The second fiber carries data from device B to device A.

This provides a full-duplex communication link.

Optical Media

Optical Media

Connectors are attached to the fiber ends so that the fibers can be connected to the ports on the transmitter and receiver.

Subscriber Connector (SC connector) - Multimode fiber

Straight Tip (ST) connector - Single-mode fiber

Optical Media Optical Receiver

Use PIN photodiodes to detect laser/LED light PIN photodiodes absorb light of 850, 1310, or 1550 nm When detects light, produces electrical signal for

network Installation of Fiber

Pull fiber through interducting (stiffer piping) to reduce bends

Cleave (cut) & polish ends Attach connector

Optical Media

Wireless Media

Standard Max.

Bandwidth

Typical throughput

Freq. Band

802.11b

(Wi-Fi)

11 Mbps 2-4 Mbps 2.4 GHz

802.11a 54 Mbps 20-26 Mbps 5 GHz

802.11g 54 Mbps 15-26 Mbps 2.4 GHz

Wireless Media A wireless network may consist of as few as two devices

Access Point Central hub for WLAN It is hard wired to the cabled LAN to provide Internet

access and connectivity to the wired network. Equipped with antennae and provide wireless

connectivity over a specified area referred to as a cell.

The range will be from 91.44 to 152.4 meters Wireless NIC

Wireless Media Wireless Connectivity

When a client is activated within the WLAN, it will start "listening" for a compatible device with which to "associate".

A probe request is sent from the wireless node seeking to join the network.

The probe request will contain the Service Set Identifier (SSID) of the network it wishes to join.

When an AP with the same SSID is found, the AP will issue a probe response.

The authentication and association steps are completed.

Wireless Media Authentication and Association types

Unauthenticated and unassociated The node is disconnected from the network and not

associated to an access point. Authenticated and unassociated

The node has been authenticated on the network but has not yet associated with the access point.

Authenticated and associated The node is connected to the network and able to

transmit and receive data through the access point.

Wireless Media Authentication Process

Open System The SSID must match.

Shared Key Requires the use of Wireless Equivalency

Protocol (WEP) encryption. Nodes attempting to access the network through the

AP must have a matching key.

Wireless Media

Frame Type Adaptive Rate Selection

Wireless Media Wireless Security

EAP-MD5 Extensible Authentication Protocol

LEAP (Cisco) Lightweight Extensible Authentication Protocol Provides security during credential exchange,

encrypts using dynamic WEP keys, and supports mutual authentication.

User authentication Encryption Data authentication

Cable Testing Inferior quality of network cabling results in network

failures and unreliable performance. All media require testing to determine the quality. Attenuation (signal deterioration) and noise (signal

interference) cause problems in networks because the data is not recognizable when it is received.

Proper attachment of cable connectors and proper cable installation are important.

Cable Testing Cable Testing Standard

Wire map Insertion loss Near-end crosstalk (NEXT) Power sum near-end crosstalk (PSNEXT) Equal-level far-end crosstalk (ELFEXT) Power sum equal-level far-end crosstalk (PSELFEXT) Return loss Propagation delay Cable length Delay skew

Cable Testing

Cabling the LAN

Media Types Symbol

Cabling the LAN

LAN Physical Layer Implementation

Cabling the LAN Ethernet is the most widely used LAN technology. An Ethernet speed of 10 Mbps can be used at the user

level to provide good performance. Fast Ethernet can be used to connect enterprise servers.

Cabling the LAN

Ethernet Media

Cabling the LAN

Ethernet Media

Cabling the LAN Straight-through

Switch to router Switch to PC or server Hub to PC or server

Crossover Switch to switch Switch to hub Hub to hub Router to router PC to PC Router to PC

Rollover A terminal and a console port

Cabling the LAN Wireless networks use radio Frequency (RF), laser, infrared

(IR), or satellite/microwaves to carry signals from one computer to another without a permanent cable connection.

A wireless network can be created with much less cabling than other networks.

Cabling the LAN In LAN design, no more than four repeaters can be

used between hosts on a LAN. This rule is used to limit latency added to frame travel by each.

Using a hub changes the network topology from a linear bus, where each device plugs directly into the wire, to a star.

Bridge break up a large LAN into smaller, more easily managed segments.

Switch alleviates congestion in Ethernet LANs by reducing the traffic and increasing the bandwidth. It operates at much higher speeds than bridges and can support new functionality, such as virtual LANs.

Cabling the LAN

Micro Segmentation of Network

Cabling the LAN Peer-To-Peer

Networked computers act as equal partners, or peers. As peers, each computer can take on the client function or the server function.

Client/Server Network services are located on a dedicated computer

called a server. The server responds to the requests of clients. The server is a central computer that is continuously available to respond to requests from clients

Cabling the LAN

Cabling the LAN

Cabling the WAN

WAN Physical Layer

Cabling the WAN

WAN Serial Connection

Cabling the WAN Routers are responsible for routing data packets from

source to destination within the LAN, and for providing connectivity to the WAN.