Wide Area Network (WAN) Devices

1. Modem (modulator-demodulator) – is a device that provides the

computer with connectivity to a telephone line. It converts data from a digital signal to analog signal that is compatible with a standard phone line. The modem at the receiving end demodulates the signal, which converts it back to digital.

– Modems may be installed internally or attached externally to the computer using a phone line.

External Modem

Internal Modem

PC Card Modem

Home PC

Office Network

ModemInternet

Public Telephone System Network (PTSN)

PTSN

Remote/Mobile User

PTSN

Main Office Network Branch Office Network

Frame Relay Modem

2. Router– Special purpose computer

whose primary function is to connect networks together forming a WAN.

– Routers are the backbone of Internet connectivity.

– Routers can also be used as LAN devices for “segmentation” purposes of large LANs to enhance their efficiency.

EtherFast® Cable/DSL Router with 8-Port Switch

Cisco 2600 Series Router

Front

Back

Network Devices Symbols

Network Protocols:

• Computers use Protocols to communicate.• Protocols control all aspects of data

communication, which include the following: – How the physical network is built – How computers connect to the network – How the data is formatted for transmission – How that data is sent – How to deal with errors

• The most widely used protocol suite is the TCP/IP (Transmission Control Protocol/Internet Protocol)

How does computers and other network devices talk to each other?

Hub/Switch

Ethernet LANs

• The most widely used LAN technology.

• Standard 100 Mbps bandwidth.

• Most common Ethernet variants:– 100Base-TX (UTP cabling)– 100Base-FX (Fiber cabling)– 1000Base-T (Gigabit Ethernet on UTP)

– 1000Base-SX (Gigabit Ethernet on Fiber)

• 100m maximum cable length per node/PC (100BaseTX).

• 550m maximum cable length per node/PC (1000BaseSX).

Typical Small Office/Home Office LAN

Horizontal Cabling

Ethernet LANs

Typical Enterprise LAN

Workgroup Switch

Backbone Switch

Router

Backbone Switch

Workgroup Switch

Backbone Cabling(Vertical Cabling)

• Hubs are passive devices switch allows connected hosts to share the network media forming a “collision domain”.

• The more hosts connected to the hub, the larger the collision domain, resulting to less bandwidth allotted for each host.

Hub characteristics:

100Mbps Hub

25Mbps Each

100Mbps Hub

12.5Mbps Each

• Ethernet LAN switch provides dedicated full-duplex connection between connected hosts.

• Hence, full network bandwidth is allotted to each hosts regardless of their number.

• Manage switches are also capable of efficiently managing the network by employing VLANs

Switch characteristics:

100Mbps Each

100Mbps Each

100Mbps Switch 100Mbps Switch

Ethernet LAN NIC

• Used to connect a PC/Printer etc. to network media.

Features:

10/100 Auto-negotiating Ethernet interface, with SNMP-based management • Configure and monitor your network from one centralized location • Power-on any PC from anywhere on the network with Wake-On-LAN support • Optimize your network traffic with 802.1Q VLAN support and 802.1p traffic prioritization

Example of a current model high-end Wireless Ethernet LAN card.