hardware (1)

Network Hardware

Network Topologies

• Bus– Devices connected to each other via bus– Passive topology– Requires terminators to prevent signal bounce– Advantages / Disadvantages-refer to previous lecture

notes

• Star– All devices connected to central “hub”– Advantages / Disadvantages-refer to previous lecture

notes

Star-Bus Topology

Ring Topology

• Nodes connected to each other in a circle

• One or more tokens

• Active topology

• Advantages / Disadvantages-refer to previous lecture notes

Mesh Topology

• Each node connected to all other nodes (or most other nodes)

• Redundancy provides reliability

• Used in WANs not LANs

Logical Topologies

• Regardless of how nodes connected, logical topologies describe how they communicate

• Ethernet– Most common logical topology– CSMA/CD-refer previous notes– Collisions and collision domains

Logical Topologies

• Token Ring– Nodes take turns controlling the token– No collisions– Active monitor– FDDI-refer previous notes

Networking Hardware

Network Interface Card

• Is called NIC• Responsible for serial-parallel conversion• Unique MAC address

– Media Access Control – Hardware address, assigned at factory

• Identified by:– Network type (100baseT, Wireless, etc.)– Slot type:

• PCI: Peripheral Component Interconnect, a local bus standard developed by Intel Corporation.

• ISA: Industry Standard Architecture bus – Type of media connection

NIC

NIC

Signal Repeater

• Clean up and regenerate signal• Devices: Repeater, hub• Counter attenuation• Unintelligent – retransmit signal to all devices

Signal repeaters: Hub and repeater

HUB:Multi-port repeater

Hub

• Simple way to connect multiple nodes

• Can enlarge network by connecting hubs (uplink)

• Might contain management tools

Bridge

• Has 2 ports – each attached to a different segment of the network

• Segments network by learning MAC address• Makes decisions to allow/disallow packets to

pass• Networks are segmented to:

– Reduce collision domain– Improve security

• More intelligent than repeaters & hubs

Collision Domain

• A group of connected devices that compete for network access.

• Only one can transmit at a time

• When more than one tries to transmit, a collision occurs

• Too many collisions affect network performance.

Switch• Multiport bridge• Uses MAC address• Can connect multiple devices• Creates multiple collision domains• Have basically replaced hubs

Switch

Switch

Switches

Switch

Switch

Switch

Wireless Access Point

• Wireless Access Point– Provide access

wired wireless– Wireless switch– 802.11 a – 54 Mbps– 802.11 b – 11 Mbps

(WiFi)– 802.11 g – 54 Mbps– 802.11 n – 108 Mbps– Bluetooth – ~ 1 Mbps

Router

• Segments network based on IP address• Makes intelligent decisions on how to “route”

packet based on IP network address

Router

Router

Router

Router

Network Address Translation

• NAT (sometimes called “NATting”)

• Used to allow internal, private addresses to communicate with the Internet

• Addresses translated private public

• Requires a device (such as a router) to support

Gateways

• Connect dissimilar network types

• Wireless access point or router(wireless to wired)

• Internet gateways(internal to external networks)

Assignment

• List out networking hardware.

• Give a brief description about gateways.

• Give a brief description about routers.

• Give a brief description about bridges.

• Give a brief description about hubs.

• Give a brief description about NICs.

• Give a brief description about switches.