Connecting devices

Bridges

Internetworkingdevices Routers

Networking devices

Gateways

Connecting devices

Repeaters1 2

3 4

Connection devices with the OSI model

3 layers 2 layers

Gateway Router Bridge Repeater

Physical data link,

Network LayersPhysical + Datalink

Physical layer

All 7 layers

7 la

yers

of

OSI

mod

el

1 Layer

A repeater in the OSI model

654321

654321

7 7O S I L A Y E R

S

O S I L A Y E R

S

Subnet R SubnetRepeater

Device A Device B

R

Repeater extends the physical length of a network

A repeater

RepeaterA

D C

B

Frame

Repeater Functions

Repeater

Regenerate Corrupted

Corrupted Signal

Corrupted SignalRegenerates

Regenerate Corrupted

Bridge to connect two LANs

HUB HUB

Bridge

LAN 1 LAN 2

A

B

CD

A

B

CD

A Bridge in the OSI model

654321

654321

7 7O S I L A Y E R

S

O S I L A Y E R

S

Subnet R Subnet

Device A Device B Repeater

Data linkPhysical

12

Functions of a Bridge

A B

C D

Bridge

Packet

Segment 1

Segment 2

Packet

Three types of bridges

I. Simple bridges

I. Learning bridges

I. Multiport bridges

Simple bridge - 1

• Primitive type• Least expensive• Links two segments• Contains a table that lists the addresses of

all the stations in each of them• Addresses are to be entered manually• Before functioning the operator must set

down & program the addresses of every station

Use of routers to connect LANs

Tokenring hub

Ethernethub

Server

ServerDevice 1

Device 2Device 5

Device 3

Bridge

Device 4

Device 6

A router in the OSI Model

654321

654321

7 7O S I L A Y E R

S

O S I L A Y E R

S

Network R NetworkDevice A Device

B

Repeater

Data linkPhysical

Network

Routers in an internet

Network E

Network A

Network B

Network C

Network D

RouterRouter

RouterRouter

Router

Router

Route for the packets from network A to network D

Network A

Network B Network C

Network D

Network Q

Use of gateways (connecting LANs and Mainframe)

Tokenring hubEthernet

hub

Server

ServerDevice 1

Device 2 Device 5

Device 3

Device 4

D i 6

Front-end

Mainframe

A Gateway in the OSI model

654321

654321

7 7O S I L A Y E R

S

O S I L A Y E R

S

Device A

DeviceBNetwork Gateway Network

654321

7

An inter net

R5

R4

R3R1

R2

R5

36 1 _53 1 _

18 1 _24 1 _

18 1 _10 1 _

08 1 _25 1 _

05 1 _24 1 _36 1 _ LAN5 LAN8

LAN10LAN18

LAN24

LAN36 LAN53 10 1 _08 1 _

Routing table

Updating the table

05 1 _24 1 _36 1 _

08 1 _05 1 _

08 2 R205 2 R2

05 1 _ 05 2 R208 2 R224 1 _36 1 _

05 1 _08 2 R224 1 _36 1 _+ one

hop

Received from R2 After adjustment

Combined R,’s new tabl

R,’s old table

Updating the table

18 2 R410 2 R4

08 1 _10 1 _10 2 R410 2 R4

08 1 _10 1 _

18 2 R4+ one hop

Received from R2 After adjustment

Combined R,’s new tabl

R,’s old table

18 1 _10 1 _

10 1 _08 1 _

Updated routing tables for R1, R5& R6

R5

R4

R3R1

R2

R5

05 2R108 3 R124 2R136 1_53 1_

18 1 _24 1 _

18 1 _10 1 _

08 1 _25 1 _

05 1 08 2 R2 24 1 _36 1 _ LAN5 LAN8

LAN10LAN18

LAN24

LAN36 LAN5308 1 _ 10 1_

18 2 R4

Routing table

Final routing tables

R5

R4

R3R1

R2

R5

05 2R108 3 R124 2R136 1_53 1_

18 1 _24 1 _

18 1 _10 1 _

08 1 _25 1 _

05 1 08 2 R2 24 1 _36 1 _ LAN5 LAN8

LAN10LAN18

LAN24

LAN36 LAN5308 1 _ 10 1_

18 2 R4

Routing table

Cost in link state routing

R5

R4

R3R1

R2

R5

36 1 _53 1 _

18 1 _24 1 _

18 1 _10 1 _

08 1 _25 1 _

05 1 _24 1 _36 1 _ LAN5 LAN8

LAN10LAN18

LAN24

LAN36 LAN53 10 1 _08 1 _

Routing table

The flooding of R2 ‘s LSP

R5

R4

R3R1

R2

R5

36 1 _53 1 _

18 1 _24 1 _

18 1 _10 1 _

08 1 _25 1 _

05 1 _24 1 _36 1 _ LAN5 LAN8

LAN10LAN18

LAN24

LAN36 LAN53 10 1 _08 1 _

Routing table

The flooding of R2 ‘s LSP

R5

R4

R3R1

R2

R5

36 1 _53 1 _

18 1 _24 1 _

18 1 _10 1 _

08 1 _25 1 _

05 1 _24 1 _36 1 _ LAN5 LAN8

LAN10LAN18

LAN24

LAN36 LAN53 10 1 _08 1 _

Routing table

Costs in the Dijkstra algorithm

R5

R4

R3R1

R2

R5

36 1 _53 1 _

18 1 _24 1 _

18 1 _10 1 _

08 1 _25 1 _

05 1 _24 1 _36 1 _ LAN5 LAN8

LAN10LAN18

LAN24

LAN36 LAN53 10 1 _08 1 _

Routing table

Networks 5, 36, 24 added

R1

LAN5

LAN36

LAN24Root

1

3

2

(ii) R2 added ; 5 permanent

R1

LAN5

LAN36

LAN24Root

1

3

2

R2

(iii) R2 permanent, 55 added

R1

LAN5

LAN36

LAN24Root

1

3

2

R2

3

LAN55

(iv) 24 permanent, R5 added

R1

LAN5

LAN36

LAN24Root

1

2

3

R2 3LAN55

R5

(v) R5 permanent, 18 added

R1

LAN5

LAN36

LAN24Root

1

2

3

R2 3LAN55

R5 LAN18

Dijkstra algorithm

R5

R4

R3R1

R2

R5

555

10LAN18

LAN24

LAN36 LAN53

2 3

9

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