NETWORK HARDWARE COMPONENTS

1. Servers:i. Performance Featuresii. Fault-tolerant Features

2. Workstationsi. Network Interface Cardii. Network Software

3. Connecting Devicesi. Repeatersii. Hubsiii. Bridgeiv. Switchesv. Routers

4. Networking Mediumi. Coaxial Cableii. Twisted Pair Cableiii. Powerlineiv. Fiber-optic Cablev. Radio Waves

Serversi. Performance Features

a. Multiple Processors

• Increasing the number of processors ‘would’ increase the speed of processing

Performance Features

b. RAM (larger and more reliable)

ECC RAM (Error Correcting Code RAM) are used in servers.

Performance Features

c. Bus capabilities

• Traditional PCs use PCI (Peripheral Component Interconnect 32-bit) bus.

• Wider buses with higher data transmission rate are used in servers… e.g. uses 64-bit PCI-X bus

Performance Features

d. Disk Interface

• Small Computer Systems Interface (SCSI)– Can handle simultaneous access to

more than one hard disk, commonly used in servers

• Integrated Drive Electronics (IDE)– For ordinary PCs

Performance Features

Serversii. Fault-tolerant Features

a. RAID (Redundant Array of Inexpensive Disks) system

Fault-tolerant Features

b. UPS (Uninterruptible Power Supply)• Data availability• Preventing data loss• Avoiding hardware damage

Fault-tolerant Features

c. Backup Server

• A backup server needs not be exactly the same as the one to be backup, but is installed with the services in duplicate and holds an updated copy of the important information.

Fault-tolerant Features

Workstations

• A workstation is a computer that allows users to make access to the resources on the network.

a. Network Interface Card (NIC) (1)• By installing a network interface

card (NIC), a personal computer can be converted to a workstation

• There are NICs for different networks, such as Ethernet, Token Ring, wireless LAN and so on

workstation

a. Network Interface Card (NIC) (2)• For Ethernet alone, there are NICs

– for different data transmission rates e.g.10Base-2, 10Base-T, 100Base-T, 1000Base-T, 10Base-F, 10GBase-LR etc.– for different cables e.g. 10Base-2 for coaxial cable 10Base-T for UTP cable 10Base-F and 10GBase-LR for fiber

optic

workstation

a. Network Interface Card (NIC) (3)

a. Ethernet NIC for UTP

b. Wireless NIC with USB connection

c. NIC for fiber optic networks

workstation

Network connection

workstation

NIC – MAC address (1)

• Each NIC has a unique identifier, called MAC (Medium Access Control) address, which is six-byte (48-bit) code burnt permanently to the ROM of the NIC.

workstation

NIC – MAC address (2)

Checking the MAC: c:\>ipconfig /all

workstation

NIC – MAC address (3)

Manufacturer’s code

Serial number

workstation

b. Network software

• The major difference between a workstation and a server on a network is in their operating system (OS)

• Servers are installed with a sophisticated Network Operating System (NOS) which manages the network and entertains requests from clients

workstation

Connecting Devices

• Repeater• Hubs• Bridge• Switches• Routers

a. Repeaters

• A repeater takes a weak signal from one side, amplifies the signal, and then sends it out from the other side.

Connecting devices

b. Hubs (1)

• A hub provides a common connection for the network cables.

• The signals entering a hub are echoed to all other ports, a phenomenon called broadcasting. Since all the cables would be occupied whenever a host transmits its signals, a hub-based network would easily get overloaded.

Connecting devices

b. Hubs (2)• Note that as each signal carries a receiver

address, only the specified node will handle the signal. Others will ignore the broadcast.

A 4-port hub

A hub used as a wire concentrator

Symbol for a hub

Connecting devices

c. Bridge

• A bridge is used to divide a larger network into smaller segments to improve the efficiency of the network

Connecting devices

c. A bridges that divides a network into two segments

Connecting devices

d. Switches (1)

• A switch is a cable concentrator that joins the network cables together

• Unlike a hub, a switch does not echo signals to all other ports. Instead, it keep a table of the MAC address for each port and is able to forward the data to the correct port.

Connecting devices

d. Switches (2)• A switch establishes a

connecting path dynamically between any two nodes. Therefore, there are less “collisions”.

• Also, a switch allows several pairs of nodes to transmit at the same time in full-duplex. As a result, switch-based networks are faster than those hub-based

Connecting devices

e. Routers (1)

• A router is a connecting device that routes data from one network to another.

• It is inserted among two or more networks.• Each router keeps a routing table internally

and is able to determine the best path for signals.

• Each port in a router is either connected to a network or another router

Connecting devices

e. Routers (2)

• A router is a vital equipment that connects a Locate Area Network (LAN) to the Internet.

• The router used in a home network is called SOHO router, broadband router or residential gateway

Connecting devices

e. Routers (3)

note: A switch keeps MAC address, whereas a router keeps IP address

Connecting devices

Reference:

Gateways (1)• Gateway refers to a node on a network

that interfaces with another network of different protocols – i.e. it translates the data formats (not the data itself) between the networks.

• In an organization, the gateway is the computer that routes the traffic from a workstation to the internet.

Gateways (2)• In a home network, the gateway

refers to the router that connects to an ISP. Therefore, the location of default gateway refers to the IP address of your SOHO router