Computer Networks

Internetworking Devices

Network Interface Card (NIC) Repeaters HUB Bridge Switch Router

NIC

Usually PCI Card Plugs into Motherboard

Separately designed for Ethernet, Token Ring, FDDI etc

Communicate with network through Serial Connection

Communicate with System with Parallel Connection

Have embedded MAC/Physical Address on a chip

NIC Functionality

Performs most of Layer Two functions LLC (Logical Link Control)

Interface with upper layers MAC (Medium Access Control)

Shared access to medium Framing

Packages Frames Signaling

Create Bits/Signals for transmission over Medium Error Detection

New NICs have built-in Error Detection Facility

Repeaters

It boosts the signal so that it could travel a longer cable length

Works at layer One (Physical Layer) Advantage

Extend cable length Disadvantage

Also propagate the noise

HUB

Connects multiple nodes in a single network segment

Works at Layer One (Physical Layer)

Broadcasting Device Multi-port Repeater Detects and troubleshoots

collisions Became Obsolete

Bridge

Used for Network Segmentation at Layer two Segmentation

Dividing a big network into parts Advantage

Less Collisions More Bandwidth

Makes MAC table Intelligence Device (Make Decisions)

Switch

Similar to HUB but is an intelligent device

Forwards Packets based upon their destination address

Increase bandwidth A switch gives any device on

the network the full bandwidth instead of sharing the available bandwidth. Intelligence ensures only

destination receives the data, at maximum bandwidth.

Decrease collisions Direct Connection between

multiple hosts

Switch

Also known as Multi-port Bridge Store & Forward Device

Store & Forward Vs Cut through MAC Table Typically works on Layer 2 Layer 3 Switches are also available Advance Switches are manageable

MAC Filtering SNMP (Simple Network Management Protocol) VLAN Setting

Router

A router is a device that forwards data packets from one network to another.

Routers read the network address in order to route data via the optimum path. Data packets which are addressed to a device at the same

site of the router will not be let through. Convert data structure from one media to another,

for example Ethernet <=> ISDN. Routers can interconnect all networks in the

enterprise. For example two different networks like a LAN and the

Internet

Router

Also Performs Segmentation Layer 3 Segmentation based upon IP (logical

address) Performs switching as switch Best Path Selection based upon Network

address Encapsulation/De-encapsulation of Packet Routing Table

Gateway

Some times router may be used as a Gateway Gateway is an essential functionality provided by router

It is a node that serve as entrance to another network and vice versa

Normally used between private networks and internet

Any packet whose address doesn’t belong to current network is forwarded to gateway

Gateway may/may not perform NAT