Repeaters and Hubs

8/3/2019 Repeaters and Hubs

1/20

REPEATER

The term "repeater" originated

with telegraphy and referred to

an electromechanical device used by

the army to regenerate telegraph

signals.

Repeaters work against attenuationby repeating DIGITAL signals that

they receive on a network.


2/20

HUBS

Hubs form the HE ART of a

network, with every separate

node of the network connected tothe hub through its ports.

All hubs can be uplinked together,

Performance will decrease as the

number of users is increased.


3/20

1. Passive Hub

Also known as CONCENTRATOR

Does not rectify or enhance

Does not enhance the performance

of LAN

Simply passes the signal through


4/20

2. Active Hub

Store and forward feature

High priority data over low priority

Acts as repeater and boosts signal

Rectifies, re-transmit packets

Helps in troubleshooting

Also called MULTIPORT

REPEATERS


5/20

3. Intelligent Hubs

manages the network resources

Improves performance of LAN

Diagnoses problem

Packet destination

Controls and minimizes

traffic/collision

Recognition on device (speed)

Also called MANAGEABLE HUBS


6/20

BASIC TYPES OF HUBS

1. ETHERNET HUB

Engineer Robert Metcalfe 1980

Also called as repeaters10 Mbps (initially)

Most affordable and readily available

manipulated to support SNMP2. NETWORK HUB

3. USB HUB


7/20


8/20

5-4-3 Rule

The 5-4-3 is a design guideline

for Ethernet computer networks covering

the number of repeaters and segments on

shared-access

In collision domain there should be 5

segments -4 repeaters-subsegments

containing active senders Ethernet backbones in a TREE

TOPOLOGY.


9/20

BRIDGES

A bridge is a LAN interconnectiondevice which operates at the DATA

LINK LAYER of the OSI reference

model.

forward frames according to their MAC(media access control) address.

Bridges can be eitherremote or local.

oTYPES OF BRIDGES:

(1) Transparent; (2) Source Route;

(3) Translational.


10/20

TRANSPARENT BRIDGESAlso called as LE ARNING AND

ADAPTIVE BRIDGES

Used to bridge networks which

have the SAME TOPOLOGY.

records MAC addresses in a

table and evaluates that

information whenever a packet is

routed toward its location.


11/20

The bridge makes a decision based on three

rules:

Source and destination

address are on the

same network:

Remove packet from

memory and do

nothing

Source and destination

address are not on the

same network:

Forward packet to the

right destination port

Destination address is

unknown:

Forward packet to all

output ports (flooding)


12/20

SOURCE ROUTE BRIDGES

is part of the IEEE802.5

standardfound primarily in TOKEN RING

NETWORKS

the SOURCE DETERMINESTHE PATH it wants to take, not

the bridge.


13/20

SOURCE ROUTE BRIDGES

2 FRAME TYPES:

o

SINGLE

ROUTE

(SR)

Framesmake up most of the network

traffic and have set destinations.

o ALL ROUTE (AR) Frames are

used to find routes.


14/20

used to bridge data between

DIFFERENT MEDIA TYPES.This is typically used to go

betweenE

thernet and FDDIor Token Ring to Ethernet.

TRANSLATIONAL BRIDGES


15/20

ADVANTAGES OF NETWORK

BRIDGES Have SIMPLE

CONFIGURATION MODES. SIMPLE TO USE

relatively INEXPENSIVE.

ALTERNATIVE TO

SWITCHES


16/20

ROUTER

Routing occurs at the

NETWORK LAYER of the OSI

modelIt is used to ROUTE DATA

PACKETS between two

networksIt reads the information in each

packet to tell where it is going.


17/20

They can connect networks WITH

DIFFERENT ARCHITECTURES

such as Token Ring and Ethernet.Routers DO NOT SEND broadcast

packets or CORRUPTED

PACKETS. If the routing table doesnot indicate the proper address of a

packet, the packet is discarded.

ROUTER


18/20

ROUTING TABLE is a set of rules, often viewed in

table format

used to determine wheredata packets travelling over

an Internet Protocol (IP) network

will be directed.

All IP-enabled devices,

including routers and switches,

use routing tables.


19/20

A BASIC ROUTING TABLE INCLUDES

THE FOLLOWING INFORMATION

Destination: The IP ADDRESS of the

packet's FINAL DESTINATION

Next hop: The IP address to which the

packet is forwarded, which SPECIFIESTHE NEXT CLOSEST/MOST OPTIMAL

ROUTER in its routing path.

Interface: This is a PORT NUMBER or

other type of logical identifier.

Metric: Assigns a COST to each available

route so that the most cost-effective path

can be chosen.


20/20

STATIC VS DYNAMIC ROUTING

STATIC ROUTING DYNAMIC ROUTINGmanually sets up the

optimal paths

uses dynamic protocols to

update the routing table and

to find the optimal path

routers do not sense thefaulty computers routers can sense a faultyrouter in the network

suitable for very small

networks

used for larger networks

the simplest way of routingthe data packets uses complex algorithms forrouting the data packets

requires minimal memory have quite a few memory

overheads, depending on the

routing algorithms used

Documents

Repeaters and Hubs