1st lecture 26th Aug 12

-- : Bandwidth :--
Bandwidth: - Speed / Capacity.
Bandwidth means bits per second.
Bits forms are: - ‘0’ or ‘1’

0 is stand for --------- 0 voltage

1 is stand for --------- 5 voltage
Computers understand Binary language. Language consists of alpha, numeric & special
characters.
Computer will react on electromagnetic signals that are a current & voltage.
Sender will generate the voltage 0 or 5 will be received from another computer called receiver.
If 0 bit wants to pass by sender then it will not generate any current on wire, so receiver will
understand that 0 bit received.
If 1 bit wants to pass by sender then it will generate 5 voltage current on wire, so receiver will
understand that 1 bit received.
10 mbps = 10000000 bit /sec
10 mbps = 1 corer bit /Sec.

Data Transfer in bits /second

CPU 1 Link CPU 2

-- : Local Area Network : --

LAN :- Lan ek samjhane ka tarika hai ki kitna bada network local kaha jayega.
LAN :- Lan is logical explanation of how big a network call local.

Definition :- Two or more computers or communication devices which are in a room, on a

floor, in a building or in a campus, if connected then it is said to be connected on LAN.

Lan cannot be define without his characteristics :-

1. LAN should be capable to provide high bandwidth /speed /capacity to communication.
2. Premises owner is the owner of LAN, you have no need to lease a link from service provider
to connect your system.

1
3. The cost to deploying LAN should be cheap, Device should be Compaq & enough powerful
to provide high bandwidth /speed / capacity to communication.
4. Larger the campus bigger the LAN. (Jitna bada campus utna bada LAN)
5. Administrative control should be centralized.
6. A campus wide LAN architecture is defined by the services that are running on network.
7. There are three important services ------- Data, Voice & Video.
8. Your campus wide LAN network architecture should be capable of running voice / Video
/Data triple play service over a single converged network. It means all three service Data /
Voice / Video should be on one network.

Disparate Network :-

PBX MCU

 Switch
 CPU 3
CPU 1

1st User
2nd User

CPU 2

3rd User

Video conferencing device (Webcam).

 If employer want to provide a data service one data cable will connect to every
computer in the campus & centralized by one device called Switch.
 PBX will use as centralized device for Voice service.
 MCU will use as centralized device for Video service.
MCU means Multimedia Convergence Unit. MCU used for multi party video conferencing.
Drawback of Disparate network:-
 Capex is high (Capital expenditure)
 Opex is high (Operation expenditure)

2
 Time taken
 2.1
80% to 90% of the enterprise organisations are running on disparate network.
2nd lecture 3rd Sep 12
Converged Network / Architecture:-

PBX MCU

 Switch
 CPU 3
CPU 1

1st User
2nd User

CPU 2


3rd User

Video conferencing device.

Definition of converged network: - Your campus wide LAN network architecture should be
capable of running Voice / Video / Data triple play service over a single converged network. It
means all three services Voice / Video / Data should be on one network.

Major benefit is CAPEX & OPEX will be low.

 PBX & MCU will connect to switch.
 All other services would be centralized by Switch.
 Voice packet size would be between 8kb to 16kb.

These three service Data / Voice / Video will segregate into two type of service.
 Data service :- transferring a stored data of your system to another system. (This service
called Best effort service)
 Real time service :- Real time voice & Video service. ( This service will used RTP protocol)
Real time protocol.

3
 How the services will work in converged network architecture?

Data Packets

PBX MCU

 Switch
 CPU 3
CPU 1
Packet N/W
IP
enabled N/W
1st User
2nd User

CPU 2


3rd User
 IP enabled phone
 Voice service would call delay sensitive or low latency sensitive service.
 Packet size would be 8KB to 64 KB.
 1/10000 Packet drop is acceptable.
 In IP enabled phone there is one programme called Voice concealment programme. Will
help user to fill the replication of drop packet.
 This device called Artificial Intelligence device.

Video conferencing device (Web Camera)

There are two type of video camera in the market.

SD :- Standard Definition This type of camera will make packet of 2.5 Mbps
HD :- High Definition This type of camera will make packet of 8.5 Mbps

4
Packet name :- I : B : P
Index --- Bare ---- Feelers

2.2
Data Service :- Forwarding data packets on the network.
e.g. :- Suppose I want to transfer Aishwaraya Rai. Jpg file for 1 user to another user. Then it will
distribute in small packets called segment. When we forward 1st packet to 2nd user & once it
receive at 2nd user, that user will check CRC code (cyclic redundancy check) if its match user will
give acknowledgment to sender please send the second packet. CRC code is help to do data
integrity check. Then 1st user will send the second packet. Once 2nd packet receives to user
again he will check CRC code if match will give acknowledgment to send 3 rd packet. While
sending 3rd packet suppose data got corrupt on wire then CRC code will not match. In this
situation 2nd user will asked to send same packet again to 1st user. Now again sending these 3rd
packets suppose data loss in the network & it has not received to 2nd user, he will not able to
give any acknowledgment. In this situation after stipulated time though 1 st user has not
received any acknowledgment he will send the same packet again. Once 3 rd packet rich to 2nd
user he will check the data with CRC code if match will give the acknowledgment to 1 st user to
send 4th packet. Once all packets will receive to 2nd user it will be consolidate by system & will
provide the 2nd user.
There is no guaranty after how much time, after how many drops or after how many
retransmission data will receive, but whenever it receive will receive as it is perfect, accurate.
Jab bhi data pahuchega satik pahuchega.
That’s why this service called Best effort service.

Real time service :- This service divided into two major services.
a) Voice service : - If I have any Mp3 file stored in my hard disk then that is not voice
service that would be a Data. If I am transferring the stored Mp3 file from my hard disk
then that is not voice service that would be Data service. Then what is Real time voice
service --- If I am able to hear the voice directly from his mouth with the help of phone
called real time voice service.
b) Video service : If I have any movie file stored in my hard disk then that is not video
service that would be a Data. If I am transferring the stored Video file from my hard disk
then that is not video service that would be Data service. Then what is Real time video
service --- With help of video conferencing kit video is captured & I can see the same
video at same time at my location is called real time video service.

5
In Real time service Quality of experience is very important. QOS (Quality of service)

Three important things are impact on user’s experience of service :-

1) Delay = Latency
2) Jitter = Inconsistent delay
3) Drops = Loss of data.
Real time service we can find in our IP enabled converged network as well as in our day to
day life Like Telephone service, Cable TV service.
Telephone service will work on TDM :- Time division multiplexing.
Cable TV service will work on FDM :- Frequency division multiplexing.

Voice Service :- Forwarding Digitise voice packets on the network.

Architecture :-
Data Packets

Switch

 Packet N/W
CPU 3
IP enabled N/W

User

To activate voice service in converge network architecture we need IP enabled phone.

The cable will come from Switch will connect to IP enabled phone & then it will goes to users computer.
Web camera will connected by USB connection with computer to avail video service on same network.

Our voice consist an log signal, which will make digitise in the form packet while transferring from IP
enabled phone.
For Example :- Suppose I want to say HAA. This analogue voice will convert into digitise packet like Ha +
aa + aa & sent on to the network. Suppose while transferring this packet one ‘aa’ packet got drop on the
network. In IP enabled phone there is one programme called Voice concealment programme.
Will help user to fill the replication of drop packet. It will replicate the ‘aa’ with use of this
programme & this will help for user’s quality of experience.

It means delay is not allowed in voice service.

6
Important points :-
 Voice service would call delay sensitive or low latency sensitive service.
 Packet size would be 8 KB to 64 KB.
 We can rip some benefit in voice service like 1/10000 Packet drop is acceptable.
 In IP enabled phone there is one programme called Voice concealment programme. Will
help user to fill the replication of drop packet.
 This device called Artificial Intelligence device.
 In IP enabled world delay is not allowed but drops can allowed.
Video Service :- Forwarding Real time video on network we need USB based connected
video camera. It will create packets of real time video. Packet would be in form of I : B : P
To activate video service in converge network architecture we need USB based connected video
camera. The cable will come from Switch will connect to IP enabled phone & then it will goes to users
computer. Web camera will connected by USB connection with computer to avail video service on same
network.
Drops are not allowed in video service. Sequencing is very important in video service.

There are two type of video camera in the market:-

SD :- Standard Definition This type of camera will make packet of 2.5 Mbps as per Impugn
standard H232 part n
HD :- High Definition This type of camera will make packet of 8.5 Mbps

Important points :-
 Video service would call drop sensitive service.
 Packet will convert into frame..
 200 millisecond delays are acceptable. Because normal human eyesight could not
understand 200 millisecond delays.
For Example :- Suppose I want to forward one real time video with help of High definition web camera.
Then it will capture 8 Mbps video per second. We cannot able to forward all 8 Mbps video at in one go.
So it will convert into small packets. That packet consist frame.

Frame would be :- I : B : P
Index: - It is the indexing of 1second video
Bare: - This is the actual video.
P means Fillers: - it will help to fill the blank in video packet.
While video receiving to receiver if it stops & start after some second it means ‘I’ packet
loss.
While video receiving to receiver if it stops & start with another shot it means ‘B’ packet
loss. (Glitch)

7
 ‘P’ packet is used as filler.

2.3

-- : Metropolitan Area Network :--

MAN :- MAN ek samjhane ka tarika hai ki kitna bada network Metropolitan kaha jayega.
MAN :- MAN is logical explanation of how big a network call Metropolitan.

Definition: - Two or more computers or communication devices or Network which are

geographically separated but within the same metro city, if connected are said to be
connected on MAN.

Man cannot be define without his characteristics :-

1. MAN should be capable to provide high to Moderate connectivity limiting factor is cost.
2. Premises owner is the owner of MAN, We lease a link from service provider to connect
your system. That is also our own link now because we are paying for that.
3. Cost of deploying MAN is high we need to lease the link from service provider.
Equipment called CPE (customer premises equipment). Most of the time would be
Router.
4. Converged architecture.
5. Larger the city is bigger the MAN. (Jitna bada city utna bada MAN)
6. Administrative control can be distributed or centralized.

Architecture :-
MCU PBX MCU
PBX

Switch Switch

 CPU 3

8
 HDFC Head office
Branch office User at CST
User at Mulund

Router (CPE)
-- : Wide Area Network : --
WAN :- WAN ek samjhane ka tarika hai ki kitna bada network Wide area network kaha jayega.
WAN :- WAN is logical explanation of how big a network call Wide area network.

Definition :- Two or more computers or communication devices or Network which are

geographically separated but not within the same metro city, if connected are said to be
connected on WAN.

WAN cannot be defining without his characteristics:-

1. --WAN should be capable to provide high to Moderate bandwidth /speed /capacity to

communication with cost is limitation factor.
2. Cost of deploying WAN is high we need to lease the link from service provider
Equipment called CPE (customer premises equipment). Most of the time would be
Router.
3. Converged architecture.
4. Administrative control should be distributed.
5. Beyond Man it is Wan.
2.4

Classification & Prioritisation of services on converged network :-

64KB 
Route
Route
Switch
2Mb rr

700Mb
CPU

9
 when all three
st
services are running in converged network architecture. It will give 1 priority to voice service, because
voice is a delay sensitive service. Then It will give 2nd priority to video service, because video is a drop
sensitive service. Then It will give 3rd priority to Data service, because Data is a insensitive service.
Every device should be more intelligent while running the services on converged network architecture.
Inelegancy related to classification & prioritisation of packet. To do classification & prioritisation on
converged network architecture called quality of service & this can be do only with the help of IP, hence
your network should be IP enabled network. Prioritisation is more important where chocking is more
like Man & Wan.
Band with Planning :-
If I have 50 members in organisation & I want to give all this Voice, Video & Data service to my
users, Then How much band with link I need to lease from service provider, Called Band with planning.
E.g. :- I will not allow all 50 user to use all 3 services at time, Then I will define who is going to use which
service & How many users will use same service at time. Suppose I decided that 32 user will use Voice
service at time, 5 users Video service at time & need 10Mb link free for Data service in this situation I
will do my Bandwidth planning as below -----
Voice 64 KB *32 =2Mb
Video 2Mb *5 = 10Mb
Data 10 Mb = 10 Mb
Total Requirement 30 Mbps.
In this situation I will lease E3 (30Mbps link)
Link Name = Band with
E1 = 2Mb
T1 = 1.544Mb
E3 = 30Mb
STM17oc3 = 155Mb
STM64/oc192 = 10GB

3.1

3rd lecture 9th Sep 12

Types of Network :-

1. Public Network :- Internet

2. Private Network :- LAN / MAN / WAN

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All service providers are connected with each other via internet.
Most of the time CPE would be Router.

Router = Router Routes within the network.

Switch = Switches within the subnet.
Switch called access device.

PBX MCU PBX MCU

Access Device

Switch Switch


CPU 1
 CPU 3

2 MB link (DLL)

HDFC Head office

Branch office User at
Delhi IS VPN User at
Mumbai P Router (CPE)

Internet (ILL) 2MB link

DLL :- Dedicated lease line. This is a SLA based service Guaranteed service. Secure service. Only for
private communication.
ILL :- Internet lease line. This is not a SLA based service. No Guarantee, Non secure service. This is shared
network.

All Service providers are be Internet service provider, But all ISP are service provider.

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SLA :- Service level agreement is agreement between user & service provider.
For e.g. :- Uptime =99.9%
Delay should not be = 200ms
Drop = Jiter ===

VPN :- Virtual private Network :-

VPN is a one feature of router. VPN will allow doing private communication over public infrastructure.
It will create one private tunnel on public network (Internet) for your private communication.
With the help of internet you can connect your two different locations.

--: Communication Technology :--

Technologies facilitate the communication it does not communicate on its own. Somebody has
to use technology to communicate technology will not communicate on your behalf.
For E. G. :- GSM Technology :- GSM is voice communication technology. When we dial a no. On GSM
phone it knows how to search that no. Under whichever cell site wherever on earth this no. is
connected, your phone will search it & create voice communication channel it will not communicate on
your behalf. In GSM technology user directly uses technology.

Communication technology has a two part :-

Layer 1 that is Hardware :- Anything that is physical or physical in nature used between two
communicating devices to form a communication channel is called layer 1.
Like :- Cables, Wires, Connectors, Pins, Pin outs, Signals, Voltage, Currents, Boosting devices.

Layer 2 that is Logic, Software, Protocols :- that drives communication on layer 1.

Technology uses :--

Ethernet technology: -- In 100% LAN we used Ethernet technology.
Serial technology: -- Mostly used in MAN & WAN.

Ethernet Technology :-- Ethernet technology is base suited technology in LAN because it fulfil all the
requirement & characteristics of LAN.

Types of Ethernet technology

Ethernet 10 mbps

12
 Fast Ethernet 100 mbps

Giga bit Ethernet 1000 mbps

10 GB = 10000 mbps...... so on 40 GBPS /100GBPS

LAN Characteristics === Ethernet technology :-

1) High Bandwidth :-- With help of Ethernet technology user can get 10 Mbps to 100 GBps speed
band with.
2) Cost Factor :-- Cost of deploying LAN with Ethernet Technology is cheap /low. Mostly wide we
use Star topology.
3) Converged Architecture :-- We can run Voice, Video & Data TrIPle play service over a single
converge network in Ethernet technology. Because Ethernet technology supports IP enable
network / IP capable / QOS capable network.
4) Coverage :-- With the help of Ethernet technology you can cover maximum coverage up to 4km
without any boosting device.

There are many medium to forward the Data in Ethernet technology :-

 Electrical Medium :- With help of electrical medium mean copper wire you can get 100mtr to
500mtr coverage. While signal running on wire it deteriorate to extend the coverage you can
use Repeater (Boosting device). But should not be boost more than 3 times, because while
boosting the signal it will boost the noise & radiation which comes with current also hence
should not be boost more than 3 times. If you boost more that 3 time can be result of corrupt
data.
 Optical Medium :- Fibber is on optical medium. In fibber the signal which are forwarding would
be in light waves not an electrical signal. There are high intensity lazar which help electrical
signal to give high speed. Fibber medium can provide 500mtr to 2Km. There many type in fibber
also we can cover 1200km coverage with the help of fibber to do that we need repeater after
80km. There is on Lazar name Raman lazar can provide 1500km coverage without any boosting.

Serial Technology :-- Serial technology is used in MAN & WAN. . Serial technology is for to use in open
environment. Serial technology can give us longer coverage. It helps to send chunk of data in longer
distance with the help of high intensity signal. Its super imposes data on high intensity signal to cover
maximum coverage. These phenomena called line driving. We will take a chunk of data & line driving to

13
a longer distance. Line driving means super imposing of signal on high intensity signal & delivering to a
longer distance & removing your signal from on high intensity signal & using it.
To avoid synchronisation problem it sends control packet. It sends RTS packet first, means ready to send.
Then second user will give CTS means clear to send. Then only data transmit ion will happen. Also user
will get acknowledgement for the same. Some level of bit correction is possible in serial technology, but
technology can not corrected the data.

Differentiate between Ethernet technology & Serial technology

Ethernet technology Serial technology

Used in Controlled environment Used in Open environment

Giving high speed in low cost Giving high speed in high cost 3.2
No controlled packet Used controlled packet to avoid synchronisation problem
Ethernet Medium :--
Ethernet Medium
Coverage Devices will be use

Co-axial Medium Thin wire (180mtr+/- 10%) (10B2) Repeater,

10 Mbps Bridge
Thick wire (500mtr) (10B5)

10Mbps, 100Mbps Twisted pair cable (10BT, 100BT, HUB, Switch

1000Mbps, 10000Mbps 1000BT, etc.) & Router

Fibber (10BF, 100BF, 1000BF etc.) Switch &

Router
Wireless.

Co-axial Medium :- Thin wire & Thick wire is co-axial medium.

14
Thin wire :-- The wire which we are use for our cable TV is RG series wire. RG 58 or 54 wires we use for
cable TV same is use for thin wire communication. The quality of this wire is inferior. We do not required
superior quality wire in thin wire communication. In cable TV we required superior quality wire because
on single wire many channels are coming on different frequency, but in communication we are sending
& receiving signal on same wire hence we can use inferior quality wire in data communication. We can
get max 200mtr coverage with thin wire. Speed would be 10mbps.

Thick wire :-- With the help of Thick wire we can cover maximum 500mtr coverage with 10mbps speed.

Devices is used in co-axial medium is Repeater & Bridge.

Twisted pair cable :-- Devices is used in Twisted pair medium is Hub, Switch & Router. Speed we can get
from 10mbps to 100Gbps band with in this medium.

Types of Twisted Pair cable

Connector RJ 45 Unshielded Twisted Pair cable

10Mbps to 100GBps
Coverage 100mtr Shielded Twisted Pair cable

15
 RJ 45 Connector

CCC :--
Connector which used in Twisted pair cable is RJ 45 with 8 pin. For telephone line the connecter we
used is RJ 11 with 4 pin.
Capacity with the help of Twisted pair cable we can get 10Mbps to 100GBps.
Coverage with the help of Twisted pair cable we can get 100mtrcoverage. 100mtr means in two
connected device should not be more than 100mtr.

Where we need to use Shielded Twisted Pair cable or Unshielded Twisted Pair cable ???

Lightning

CPU 2
CPU 1

Electro
Magnetic signal

16
 Radiation

In open environment cable network Lightning & electromagnetic signal (Radiation) impact on
data communication. User will get bad performance in form of delay & jitter. Performance will bad it
mean user could understand that lightning & radiation is impacted on our data communication.

Solution: -- Solution is Shielded twisted pair cable. In shielded twisted pair cable upper side of the cable
have foiled (Metal net) there are some special types of connector available in the market. Whose half
part is made of metal & half part is made of plastics. When we crimp this connector to shielded twisted
pair cable, cables metal net would get connected to half side of metal on connector. All ways the
devices connector make of steel. When you connect this connector to any device this metal connector
would get connect & the radiation would get grounded hence this will not impact on our data.

In closed environment (In homes & office) we can use unshielded twisted pair cable.
But we need to take below mention precautions to get good performance.
This unshielded twisted pair cable should not be passing near to tube light.
This unshielded twisted pair cable should not be passing near to Electrical wire.
Or at least 6 inch gap should be there between electrical wires & unshielded twisted pair cable.

Because it create Radiation which will impact on data.

Category of medium :--
CAT 4 = = 10Mbps
CAT 5 = = 10Mbps to 100Mbps
CAT 6 = = 10Mbps / 100Mbps /1000Mbps
CAT 7 = = 1GB
CAT 8 == 10GB

How wires are important in communication with speed factor???

Your system network card defines the speed, of your data communication. How much data can transfer
on you wire per second would be define by network card. If your medium is not conducive to carry the
speed which is given by network card then you will not able to achieve the expected speed in data
communication. Whatever the strength is there in my network card to give speed same strength should
be there in wire to carry the data on same band with.
e.g. Sachin’s Farari gadi will give the good speed on express highway not on ordinary road.

What is there in the wire which creates difference between data transmit ion???
Primarily there are two different in wires that is thickness & no. of twist. CAT 5 is thicker & has more
twist as compare to CAT 4. Thickness of wire is directly related to capacity / speed & Twist is related to
coverage.
17
Why Thickness of wire is directly related to capacity / speed???
More thick cable has more electrons which help them to give more band width. As per 9 th standard
physics.

Thickness of wire is directly connected to band with. The more wire thick will carry more band
width.

4.1

4th lecture 16th Sep 12

Why Twist???
Twist is directly connected to coverage. We can use flat (Non Twisted) wire for the
communication as well. Most of the time flat wire gives 3 to 25mtr coverage. If you are using twisted
wire can easily give 100mtr coverage.

Why Twist???
Right hand Thumb rule in 9th standard physics :- According to this rule If current is flowing on wire with
thumb direction it will create radiation in same direction will carry with current anti clock wise on wire.
This radiation will impact on data which is carrying by another cable behind this cable.
If two wire are carrying current on same direction there radiation will get abdicative effect will impact
on 3rd wire data. That’s why flat wire will not give more that 25mtr coverage.
(Jab wire per thumb ke direction per current jab flow hoga to is current ki wajah se hi radiation paida
hoga jo wire ke irda girda wire pe anticolock wise chalega)

Radiation

Cable

18
Crosstalk rule :- If two wire’s which are carrying current in 180C phase shift (Means mirror image signal)
If tightly coupled then there radiations which generated them have cancelling effect.

Mirror Image

Radiations will cancel

Radiation between on twist pair will not affect two second twist pair because its radiation will cancel
within the twist.

That’s Why cable should be twist to avoid radiation effect of the current carrying by cable.
If you are using twisted wire can easily give 100mtr coverage.
Devices used in communication :--

Edge device:-- Computer or any device where user will

PC seat & accessed device. This device called Edge device.

Access device :- Switch is one access device. With help

Switch of switch you will get connected to network. Switch
switches within the subnet.

Routing device :- Router is one routing device. Router

Router
Router Routes between the networks.

Types of cable used in Ethernet communication :-

19
Straight over cable :-

USER 1 USER 2
1(rx+)
1(tx+) 2(rx-)
2(tx+)
3(tx+)
6(tx-)
3(rx+)
6(rx-)

The cable which comes from pin no. 1 will connect to pin no. 1 & pin no. 2 to pin no. 2. Pin 1 &
pin 2 cable will twist to each other. It will transmit the data on pin 1 (tx+) for the same data it will create
mirror image on pin 2 (tx-) will help to cancelling the radiation. For 2nd end user will receive data on pin
1 (rx+) & mirror image of the data on pin 2 (rx-).
If 1 st user want to receive the data then he will receive on pin 3 that is 1 st user (rx+) & pin 6 will
mirror image of the same data that is 6(rx-)
Mostly people have understanding that pin 1 cable will transfer the data & pin 2 cable will
receive the data, but this concept is wrong pin 1 cable & pin 2 cable would tightly couple with each
other both will transfer the data one will transfer the data & 2 will create mirror image of the data then
only it will cancel the radiation.
Cross over cable :-

USER 1 USER 2
3(rx+)
1(tx+) 6(rx-)
2(tx+)
1(tx+)
2(tx-)
3(rx+)
6(rx-)

The cable which comes from pin no. 1 will connect to pin no. 3 & pin no. 2 to pin no. 6. Pin 1 &
pin 2 cable will twist to each other. It will transmit the data on pin 1 (tx+) for the same data it will create
mirror image on pin 2 (tx-) will help to cancelling the radiation. For 2nd end user will receive data on pin
13(rx+) & mirror image of the data on pin 6 (rx-).
If 1 st user want to receive the data then he will receive on pin 3 that is 1 st user (rx+) & pin 6 will mirror
image of the same data that is 6(rx-)

Used of cable’s :-

20
 PC Switch Straight Cable

Route Straight Cable

Route Switch
rr

Switch Switch
Cross Cable

Route
Route Route
Route Cross Cable
rr rr

PC PC Cross Cable

Route
Route
PC rr
Cross Cable

Whenever we connect anything to switch will connect with straight cable will used. PC & router
will have mouth on pin 1 & switch have ear on pin 1. When we are connecting same device in network it
will connect with cross cable, but when we want to connect PC to Router it will connect with cross cable.

Self crossing & Auto sensing devices :- Now a days the devices available in the market have self
crossing & auto sensing capability. It means device himself identify that on which port user will send the
data & receive data. According to that device will adjust him for data transmit ion.

21
Roll over cable :- Roll over cable is the Cisco’s preparatory cable. This is not Ethernet cable

Pin 1 Pin 1
Pin 2 Pin 2
Pin 3 Pin 3
Pin 4 Pin 4
Pin 5 Pin 5
Pin 6 Pin 6
Pin 7 Pin 7
Pin 8 Pin 8

Whenever you purchase Cisco’s Router & Switch there will be having communicating port.
To configured Router & switch we required Roll over cable.
To Configured Switch this cable will connect to console port.
To Configured Router this cable will connect to Auxiliary port.
Pc com cable called Rs232 port.

Switch

Ethernet port Auxiliary port

Console port
P
Com 1
Router Roll over
RS232
Cable
Port

Com 2
Ethernet port Auxiliary port
Ethernet port Auxiliary port
Serial port
Serial port 22
Console port
Console port
Power over Ethernet (POE):-- In Ethernet communication we use 4 wire’s. That is pin 1, 2, 3 & 4. In
Ethernet & fast Ethernet only 4 cables used for communication because it forward only 10mbps to
1000mbps data, but Giga bit Ethernet all 8 pins used for data transfer.

If we are doing communication on pin 1, 2, 3 &4 then why there are additional 4, 5, 7, & 8 cable pin???
Reason this cable will help to provide power to connected device (for power over Ethernet). If
your switch is not POE capable switch then you need to connect power injector module to supply power
for connected device like IP phone.
Pin 4, 5, 7 & 8 cables will provide 48V power supply to device. It will not provide 230V. Also
cable is twisted hence this power supply will not impact on data, because it will cancel the radiation.
In Giga bit Ethernet all 8 pins use for communication then to it will provide power on 4, 5, 7 & 8
cable it will carry data as well as power, because it will carry on different frequency level.
Fibber optics cable :-- Devices is used in Fibber optical medium is Switch & Router. Speed we can get
from 10mbps to 100Gbps band with in this medium.

Fibber is made of plastics. Many people filled that there is whole (Ched) in fibber, but this is wrong it
will be solid plastic. Upper side of the cable chemical & to reflect mirror polish would be there. Which
help signal to does not get reflect out of because of plastics.

CCC :--
Connector which used in Fibber optic cable LC / SC / ST / FC.
Capacity with the help of Fibber optic cable we can get 10Mbps to 10GBps /40GBps /100GBps.

23
Coverage with the help of Fibber optic cable we can get 500mtr /2Km / 40Km /100Km / 2500Km also
can go without boosting coverage. If you are using Raman laser it can provide 1200Km coverage without
any boosting. In Ethernet technology 500mtr /2Km / 40Km /100Km coverage you can cover easily.

Types of Fibber optics cable :- The major difference is Dia meter (on micron) it cannot be understand
by normal eye sight.

1. Single mode Fibber optics cable (More than 2km)

2. Multi mode Fibber optics cable (500mtr to 2 Km)

Also

1. Indoor Fibber optics cable

2. Outdoor Fibber optics cable
The major difference is solid (Strong)
Outdoor fibber is very solid made with plastics upper side shield, roads, metal, double cover of plastics.

Why single mode fibber giving more speed compare to multimode fibber???
Signal will get more time to reflect in plastics in more thick (multimode fibber) fibber. /because of broad
diameter signal get more space to reflect; hence it may take time to reach at destination.

Fibber Module :--

Fibber Module

SFP GBIC

500 Mtr SX--- Short haul also called as Short reach (SR) (20,000rs) cisco

2 Km ++ LX /LH --- Long haul also called as Inter mediate reach (IR)(80K to 100K)

40 Km ++ ZX --- Ultra long haul also called as Long reach (LR) (20 lac rs)

In Single mode fibber will use ZX fibber module.

In Multi mode fibber will use SX fibber module.
LX fibber module can use in both type of fibber.
Where we can use Fibber cable or twisted pair cable???
In closed environment we will use twisted pair cable. Within the room, building I will use twisted pair
cable. In open environment we will use fibber optic cable. If I want to connect two switch within the
campus between two building I will use fibber, because fibber is a made of plastic carry light waves.
Light will not get distract because of electromagnetic radiation. Also it will give long coverage.
24
How technology get innovate???
Whenever you innovating any technology. First you will make on one white paper that what you
are going to use? How things will work? What will be the outcome? & submit to agency like IEE, ICFI,
ANSI.....Then many people will research & cross question you about the same. Once technology finalised
you have to make it standardise of your technology with the help of this agencies. Then only it can be
use by other users also which help you to do communication with them. If you are not standardising
your technology & using for own called proprietary technology.

Ethernet Technology ----

 Fundamental ===== CSMA /CD
 Standard ==== IEEE 802.3
 Protocol ==== ARPA (Cisco Protocol)

Ethernet technologies fundamental is CSMA/CD. Which standardise by IEEE (Institute of Electronics,

Electrical of Engineers) & Standard are 802.3
Every technology has two layer one is hardware & 2nd is protocol. Cisco is using ARPA protocol with this
technology. ARPA is the software designed by Cisco in Ethernet technology.
5.1

5th lecture 23rd Sep 2012

-- : CSMA /CD :- Carrier sense multiple access / collision detection :--

Two or more computers or communication devices can connect over a single medium. They can
communicate with each other like they are part one democratic world. But before communicate they
have to sense for medium, If medium is available not using by any other computer, computer can put his
data on wire. For this instant he will be the only owner of medium, nobody will talk everybody will listen
(means other will not able to put their data on wire). Whenever data send it will send with source code
& destination code. Frame will received to all connected device but respond will from the computer
who’s MAC has been address as destination code

PC 1 PC 2 PC 3 PC 4

AAA BBB CCC DDD

25
 MAC address (Media access code)
It is a 6 Byte means 48 bits address in hexadecimal format to every Ethernet card. It also called BIA(Burn
in address) or Layer 2 address or physical address or machine or hardware address.

00:1A:2B:3C:4D: 5E

Manufacturer code
This manufacturer code given by IEEE because they only standardised this concept. Whenever
data will send it will send with source code & destination code, in that systems Mac address will be use.
Mac address will by unique. Mac address used in Ethernet technology but not in serial technology.

Frame
AAA DDD DATA

Source address / Destination address

Example :- In given diagram suppose PC 1user want to send the data to PC 4. Then in frame AAA will use
as Source address & DDD as a Destination address. Which is a MAC address of PC 1 & PC 4 & then data.
This frame will receive to PC 2 & PC 3 as well. When frame receive to PC 2 & PC 3 they will check
destination code found not matching with them because there MAC address is BBB & CCC they will
5.2 is matching with his
discard the frame. When frame will receive to PC 4 it found that destination code
MAC address that is DDD so he will reply.
Collision detection :-- It may so happen that two computer s may fill like to do communication at a
same time, If both system sense medium at a same time & found it is available they will put their frame
on wire at same instant. If two computer s put their frame on wire at same instant this frame may
collide. CSMA /CD say no issue because CSMA / CD have collision detection & avoidance mechanism.

How Collision Detection???

Technology have two layer 1 is Hardware & layer 2 is logic /software /protocol. We will learn in
both layers prospective.

From Layer 2 prospective How Collision Detection???

In Ethernet communication whenever computer sends their data in frame they will apply CRC
code. CRC code is apply to do data integrity check.
When two computers sense medium at same time & found medium are available they will put
their data on wire at same instant. When they put their data on wire at same instant this frame will
collide. After colliding frame will not get destroyed it will distorted the signal. Because frames are
carrying signal & signal means energy. Energy cannot be created not be destroyed. When this frame get
collide it will distorted. When this distorted frame resonates (receive) to all other connected computers.
When this collided frame receive to all connected computers first they will check CRC code, though this
frame is collided CRC code will not match it will consider corrupt frame & will discard it.

26
From Layer 1 prospective How Collision Detection???
When two computers sense medium at same time & found medium are available they will put
their data on wire at same instant. When they put their data on wire at same instant this frame will
collide. After colliding frame will not get destroyed it will distorted the signal. Because frames are
carrying signal & signal means energy. Energy cannot be created not be destroyed. When this frame get
collide it will distorted. When this distorted frame resonates (receive) to all other connected computers.
Whoever will received this collided frame first will send jamming packet on wire to all other
connected computers. Connected system back off from communication.

Why Collision avoidance is important???

In CSMA /CD when a computer has to communicate if computer have 700MB worth data which
is to be delivered then it will create a 2 to 3 thousands segments of this data it will never happen that
computer will acquire medium and keep with him till send all segment. Computer cannot hold medium
till deliver of all segment. For every segment to deliver computer has to bid for medium. To finding out
the medium is available or not & if available then it acquire called Bidding process. After getting medium
they can send 1 segment at time. All computers will bid for medium. Every computer will bid the
medium one after other hence they will fill that they are connected but at time only one computer will
send data. If two computers sense medium at same time & found medium are available they will put
their data on wire at same instant. When they put their data on wire at same instant this frame will
collide. When they detect this collision they will go back off. After some time again they will try to
5.3
acquire medium, if again two computer sense medium at same time, again collision will happen. Hence
not only collision detection is important there has to be mechanism of collision avoidance.
How Collision Avoidance???
Whenever computer will receive collided frame or jamming signal, computer will go in back off
state. Back off means integral wait state. Integral wait state also called as exponential wait state also.
Integral wait state will in micro or millisecond. Every computer will decide his own integral wait state.
There is no any relation between two computer wait states. Wait state is integral means it can be
decrease or increase. Wait state is depending upon no of collision. When computer is in integral wait
state they can received data (Sun sakata hai) but cannot transfer (Bol nahi sakata) the data.

PC 1 PC 2 PC 3 PC 4

AAA BBB CCC DDD

20ms 5ms 20ms 50 millisecond

27
For e.g. :- In given diagram BBB has a 5ms wait . After 5ms BBB will try to acquire medium all other are
still in wait state hence BBB will easily acquire the medium & lead the medium & can send more than
2MB data in 15ms. After 15ms second AAA & CCC will come out from integral wait state so they will
again start bidding for medium. In this way computer will avoid repetitive collisions with the help of
integral wait state.
Collision is more if more number of computers connected. 100 to 200 computers. For 10 to 50
users there will be no collision.

If someone ask it is CSMA /CD (collision detection) not CA (collision avoidance) then how Collision
Avoidance???
Wireless & wire line both type of LAN work as per 802.3 Ethernet standards. Collision avoidance
is possible in both type of wireless as well as wire line LAN, but collision detection is available in wire line
LAN not in wireless LAN because communication medium is waves. That’s why collision avoidance is a
part of CSMA/CD. In wireless LAN it called CSMA/CA.
5.4
Types of communication in Ethernet technology:-- There are 2 type of communication in Ethernet
technology. Computer will accept the frame in below three conditions.
1. Unicast: -- When frame comes with only his own MAC address as a destination code called
unicast communication.
2. Multicast: -- If computer is a part of any group it will also accept the packet which has been
address for that group called multicast communication.
3. Broadcast: -- Those packet comes on wire for every connected device would also accept by PC
called Broadcast communication.
-- : DHUDH KA DHUDH PANI KA PANI :--

Upper layer protocol stacks:--

Whenever we plug the Ethernet card that is layer 1 of Ethernet technology, your computer will
detect the card. Then it will install the driver of Ethernet card that is layer two (software / logic), which
help to drive communication on this network. Once driver install of Ethernet card it will reflect in
network neighbourhood that LAN card 1 is ready for communication, Ethernet technology is ready for
communication in windows operating system. But as per technology rule technologies facilitate the
communication it does not communicate on its own. Somebody has to use technology to communicate.
Technology will not communicate on your behalf.
For E. G. :- GSM Technology :- GSM is voice communication technology. When we dial a no. On GSM
phone it knows how to search that no. Under whichever cell site wherever on earth this no. is
connected, your phone will search it & create voice communication channel it will not communicate on
your behalf. In GSM technology user directly uses technology.

28
 But in data communication technology user cannot be use technology directly. There has to be
agent who works as mediator between technology & user. This mediator called IP upper layer protocol
stack.
5.5

There are many upper layer protocols like IP / IPX / Apple talk. But as IP used widely everywhere
we will talk about IP based communication. IP upper layer protocol make available many tools &
application to user for his communication. If user wants to send data it will allow user to use FTP tool. If
user wants to do remote console it will allow user to use TELNET.
e.g.:- If user want to send any file with FTP tool it will give command “FTP 10.0.0.2 put file ash.jpg” In
this 10.0.0.2 is a destination IP address. With FTP tool ash.jpg file will receive to 2 nd user.

Machine /user will identify by IP address of the system in IP based communication. Which
widely use everywhere now a day. IP upper layer protocol is a mediator between technology & user in
communication technology. User cannot directly communicate in communication technology.

IMP points :--

 Data communication will do by IP on user behalf.
 IP upper layer protocol is responsible for end to end / error free / accurate
communication.
 IP is not for PC it will be for network card.

Whenever you configured IP address where does it go??? Whenever we install Ethernet card it
will reflect in network neighbourhood that LAN card 1 is ready for communication, Ethernet technology
is ready for communication in windows operating system. But as per technology rule technologies
facilitate the communication it does not communicate on its own. Somebody has to use technology to
communicate. Technology will not communicate on your behalf. In data communication IP upper layer
protocol will work as a mediator, in data communication technology user will not directly communicate.
I will go in my LAN card property & select TCP/IP. As soon as I select TCP/IP it means I bind (accept) that
IP will help user to communicate on this technology. Then this protocol will ask for IP address. IP is not
for PC It will be for network card. If there are 10 network cards then we required 10 different IP
addresses. Once I gave IP to network card, IP & its MAC address mapping will get stored in ARP table. In
every type of operating system it will be on /etc directory. In same way there would Host table, Routing
table. To find out the detail of routing table command is router print.
In windows OS on /etc directory

ARP Table Routing Table Host table

10.0.0.1 ==00:1A:2B:3C:4D: 5F Nic 1 == 10.0.0.1 Host PC & his IP address
PC 1 == 10.0.0.1

29
  IP address is layer 3 protocol
 MAC address is layer 2 addresses.

ARP tool :-- As soon as person seating on computer says FTP 10.0.0.2 put ash.jpg means he want to
send ash.jpg file to 10.0.0.2 My upper layer protocol will put ash.jpg file, segment it, mark it CRC code &
ask technology to deliver the data to 10.0.0.2 Technology will refuse to deliver this file because
technology does not understand 10.0.0.2 Technology know computer by their MAC address. IP upper
layer protocol knows by their IP address. Hence IP upper layer protocol takes help of associate tool &
asks MAC address of 10.0.0.2 ARP tool maintains ARP table so it will look what is the MAC address for
10.0.0.2 but initially this detail would not be available in ARP table. It would have only its own IP and
MAC address mapping. Sp ARP tool will send ARP broadcast. ARP broadcast means Send IP request for
MAC. It means whom soever is the 10.0.0.2 please provide your MAC. It will receive to all connected
system means CCC & DDD also but IP is of BBB, Hence BBB will answer with help of his own ARP table.
When user 1 learns the MAC address for 10.0.0.2 is BBB it will save same information in his ARP table.
Then data communication will happen.

PC 1 PC 2 PC 3 PC 4

AAA BBB CCC DDD

6.1
10.0.0.1/24 10.0.0.2/24 10.0.0.3/24 10.0.0.4/24

6th lecture 30th Sep 2012

-- : IP flow :--
Rules of Ethernet communication:-
1. Final communication between two communicating pairs connected over Ethernet will happen
by using MAC address.
2. Traffic between two communicating devices connected over Ethernet will switch if they belong
to same subnet.

What is ping??? (Packet inter network groper)

Ping is a tool / application of IP upper layer protocol stack. That is used to get network layer / IP
layer / layer 3 status. Ping sends ICMP (Internet control messaging protocol).Ping is also use for ----
 To check connectivity
 To calculate latency (delay)
 To verify link quality (drops).

Why we required layer 3 status?

30
 For e.g. If I am sending some data to 2nd user & session got disconnected after 95%, I again try to
send same file this after 99% session got disconnected. Why session is getting terminated? Ping is a
monitoring tool. In which you can send the packet of different different size, so with the help of ping I
could find out of the 5 packets are received to user or none of the packet is received. Which help me to
know there is problem in upper layer protocol or problem in link?

How I could know that there is problem in upper layer protocol or problem in link with help of ping???

127.0.0.1 :--- 127.0.0.1 is a local host / loop back address. If we ping 127.0.0.1 on our system without
any connection then to us will get response. This proof that ping is not only for connectivity check. It is
for to get network layer status.
This is a universal IP for every systems local host address for software developer.

-- : IP flow :--

Switch
PC 1 PC 2 PC 3 PC 4

AAA BBB CCC DDD

10.0.0.1/24 10.0.0.2/24 10.0.0.3/24 10.0.0.4/24

FRAME

DATA 10.0.0.1 10.0.0.4 AAA DDD DATA 10.0.0.4 10.0.0.1 DDD AAA

SIP DIP SMAC DMAC SIP DIP SMAC DMAC

Response
frame 31
 Layer 3 Layer 2

DATA 10.0.0.1 10.0.0.4 AAA FFF

ARP Broadcast
SIP DIP SMAC DMAC

Layer 3 Layer 2

IMP point: SIP & DIP is layer 3 information.

SMAC & DMAC is layer 2 information.
Broadcast MAC: - FF: FF: FF: FF: FF: FF
Broadcast IP: - 255.255.255.255

If I want to ping 10.0.0.4 means I want network layer status of 10.0.0.4. It will create frame like
-------->>>>>>
DATA 10.0.0.1 10.0.0.4 AAA DDD FRAM
E
What is your SIP DIP SMAC DMAC
Network layer
status?
Layer 3 Layer 2

Whenever we want to send data to any user we need to add some header like whenever we
want to write later we write address of sender & receiver. In header 1st field will be SIP means source IP.
That is its own IP address which he will get from routing table (10.0.0.1). DIP means destination IP
means to this frame suppose to go. That he will get from command (ping 10.0.0.4) SMAC means source
MAC. That is MAC address for SIP. Which he will get from ARP table. DMAC means Destination MAC
from whom reply is required. That also system will check in his ARP table. IF that entry is there in his ARP
table, it will use that system MAC as destination MAC. But if there is no entry in ARP table about 10.0.0.4
IPs MAC then it will send ARP broadcast.

32
ARP Broadcast :- ARP Broadcast means send IP request for MAC. It is used to learn MAC address of IP
address for whose entry is not available in ARP table. It will create frame like ------>>>>>

DATA 10.0.0.1 10.0.0.4 AAA FFF

ARP Broadcast
What is your SIP DIP SMAC DMAC
MAC address?

6.2
Layer 3 Layer 2
In this SIP, DIP & SMAC will captured as per above mentioned process. And for DMAC it will use
FFF (FF: FF: FF: FF: FF: FF) which is a broadcast MAC. All PCs will receive this frame. The meaning of this
frame will to whosoever is the owner of 10.0.0.4 please give your MAC address. All system will receive
the frame because this is broadcast frame.
For e.g :- When BBB & CCC will receive the frame with the help of layer one technology. They
will check layer two information that is destination MAC. They will found frame is for FFF, but then to
they will accept the frame because this is broadcast frame. Then they will check layer 3 information &
found this frame is for 10.0.0.4 & not for them because there IP is 10.0.0.2 & 10.0.0.3 respectively as per
there ARP table, Then they will discard the frame, but before discard the frame they have visibility of
layer 2 & layer 3 information they stored the AAA (SMAC) & his IP (SIP) detail in their own ARP table.
(Muft ka chandan ghis mere nandan). Once frame receive to DDD with the help of layer 1 technology. He
will check layer two information that is destination MAC. He will found frame is for FFF, but then to he
will accept the frame because this is broadcast frame. Then he will check layer 3 information & found
this frame is for 10.0.0.4 with help of ARP table he will understand that this frame is for him & then he
will reply.
Response frame:-- DDD will create response frame in reply to broadcast frame like-------->>>>>>
DATA 10.0.0.4 10.0.0.1 DDD AAA

My MAC address SIP DIP SMAC DMAC

is DDD.

Response
frame

Response frame will received to all connected device on network, When BBB & CCC will receive
the frame with the help of layer one technology. They will check layer two information that is
destination MAC. They will found frame is for AAA, now they will discard the frame without checking
layer 3 information because now this is not broadcast frame this is uncast frame. Once this frame
received to AAA it check layer 2 information that is DMAC found AAA for him only he will accept the
frame. Then will check layer 3 information that is DIP 10.0.0.1 will check his own ARP table found
matching will check the data. In data it get information of MAC address of 10.0.0.4 He will stored the
entry in his ARP table. Now the frame which has been park because of previously not aware of MAC of
10.0.0.4 will send. In this way data communication will happen. This is called IP flow.
33
 6.3

Ethernet Devices :--

Ethernet Devices
Coverage Medium will be use

Repeater
10Mbps only Co-axial Medium

Bridge

HUB Twisted Pair Cable

Switch
10Mbps, 100Mbps Twisted Pair & Fibber Cable
1000Mbps, 10000Mbps Router

Repeater & Bridge : -- Repeater & Bridge work with Co-axial medium. This device now not use in
network.

-- : HUB :--

HUB :-- HUB is a layer one device. HUB is not an intelligent device. He will not understand that data is
collided or not. He will forward the collided data also to all other connected device. HUB is used with
twisted pair cable. HUB is a layer 1 device /Boosting device.

1. HUB is a dumb device.

2. HUB is an electrical device.
3. As soon as HUB received an electrical signal on his port. It will boost the signal / Restore the
signal & then forwarded it to all other port but not to same port.
4. HUB will extend the network.
5. Every port of HUB shared the same bandwidth. HUB is a shared bandwidth device.
6. Every port of HUB is a member of single collision domain & single Broad cast domain. HUB is a
single collision & single Broadcast domain device.

34
HUB Advantages:--
1. HUB extends the network & increase coverage area.
2. More computers can be connected.
3. HUB distortion the signal level.

HUB Disadvantage:--
1. HUB extends the network but bandwidth remains same.
2. Probability of acquiring the medium will reduce.
3. Bandwidth per computer will reduce & probability of collision increase.

HUB HUB

PC 1 PC 2 PC 5 PC 6
PC 3 PC 4

AAA BBB CCC DDD EEE GGG

Drawback of HUB :-- HUB exactly work as per CSMA/CD rule. At one instant one computer can talk
other will listen. This will impact on data transfer performance. It will work slowly. If many computers
connected to medium it will impact on performance.

-- : SWITCH :--

Switch as an intelligent device. As soon as switch received frame on his port, it will open layer 2
information read the destination MAC address, refer MAC table & then take forwarding decision. MAC
address is a layer 2 address, MAC table is layer 2 table, and hence switch is a layer 2 device.
As soon as switch received frame on his port. It will open layer 2 information read the
destination MAC address, refer MAC table & forward to the relevant port not to all ports.
Switch segment the network where as HUB extend the network

MAC Table (Mapping of Port no & MAC address of system which connected on that port)
1 == AAA 1 == BBB 1== CCC 1==DDD
2 == EEE 3 == GGG
HUB 4 == HHH 4 == III 4== JJJ 4== KKK HUB

35
 1
2
Switch 3 4

AAA BBB CCC DDD EEE GGG HHH III JJJ KKK

7.1 & 7.2

7th lecture 7th Oct 2012

Switch & Bridge are similar device but use on different medium. Switch is used on twisted pair &
fibber. Whereas bridge use on thick wire & thin wire. Normally bridges have less no. of ports compare to
switch. Bridge has maximum 16 ports where as switch is called multi port bridge & has high port
concentration.

Switch refers MAC table to take forwarding decision. Hence MAC table should be populated
with MAC address. MAC address can be added to MAC table by two ways:--
1. Statically by Administrator. Static entries will add by administrator would be permanent.
2. Dynamically by switch. When frame travels by switch, switch can do MAC learning.

How switch can do MAC learning???

Whenever switch receive frame on his port. It will open layer two information & will ask from
where did you come? ( Kaha se aya hai? Switch is the only device will ask this question. Other devices
will always ask where do you want to go? Kaha jana hai?) First it will read Source MAC address from
packet & will make entry of this MAC address in his MAC table again the port on which it was received.
MAC table size should be precise & concise for following reasons:-
1. For performance purpose.
2. For quick reference & fast forwarding. (Can be the cause of delay)
3. To conserve the resources. (Memory & processing power).

Solution :-
To make MAC table precise & concise entries in MAC table have to be control & steal entries have to
be deleted from MAC table.
Any entry in MAC table that is neither receiving frame nor forwarding frames is considered as steal
(bassi) entry. Switch will remove the steal entry from the MAC table after stipulated time. Stipulated
time can be 5 to 30 minutes depending upon switch to switch. Stipulated time will be 5 minute for
Cisco made switch.

7.3 & 7.4

36
Switch Operation :-
1) When switch received a broadcast frame on his port. It will create multiple copies of frame &
forward it to all other port but not to same port.
2) Switch does not broadcast. Because switch is technology device. Technology facilitate
communication cannot be participate in communication. Switch can forward the broad cast
frame by creating multiple copy of that frame.
3) If destination MAC is not known, available in switch’s MAC table. Switch will create multiple
copies of frame & forward the frame to all other ports.
4) If sender & receiver on same port switch will discard the frame. Switch switches between the
two ports not within the port.
5) If sender & receiver are on different port it will bridge the information to relevant port only &
not all other port. (Where as HUB will forward the frame to all port)
6) Switch allows simultaneous communication between multiple communicating pairs connected
on different port. Switch works as per CSMA/CD rule but with the help of Hardware it removes
the clause of software.
7) When Switch sense medium & found that medium is not available then Switch can buffer the
frame it will not discard the frame immediately. This is possible only in Cisco made Switch.
8) Every port of switch has its own dedicated bandwidth. Switch is a dedicated bandwidth device.
9) Every port of Switch is a member of separate collision domain & Switch is a multiple collision
domains device.
10) Every port of Switch is a member of single broadcast domain & multiple collision domains
device.
11) Switch is a single broadcast domain & multiple collision domains device.
12) Switch will discard the collide frame. Switch will not forward collided frame.

MAC Table (Mapping of Port no & MAC address of system which connected on that port)
1 == AAA 1 == BBB 1== CCC 1==DDD
2 == EEE 3 == GGG
HUB 4 == HHH 4 == III 4== JJJ 4== KKK HUB

1
2
Switch 3 4

AAA BBB CCC DDD EEE GGG HHH III JJJ KKK

37
Fadu tip:--
If in given diagram suppose AAA want to speak BBB & EEE want speak CCC. Both will sense the
medium & if they found medium is available both will put frame on wire at same instant. This frame will
collide. AAA will understand with help of jamming signal that data is collided but Switch will not
transmit collided frame back to EEE. Then how could EEE understand that collision is happen & now EEE
have to resend the frame???

Ans :-- Switch is taking participation in communication not communicating on users behalf. IP is
doing actual communication. In data communication IP upper layer protocol will become mediator in
user & technology. There are two types of IP communication :--
1. Connection oriented (TCP)
2. Connection less (UDP)

UDP communication is the best effort delivery. That is not guaranteed communication.
TCP is guaranteed delivery communication that use acknowledgment & retransmit if required.
If acknowledgment not received in stipulated time it will retransmit.
Normally it would retransmit a maximum of 3 times before terminating the session.

By with the help of TCP communication EEE could understand that frame is collided & he have to
retransmit the frame. If EEE is using the UDP communication then he will not understand that frame is
collided. TCP/IP is widely used concept in all over the across.

7.6

--: MTU (Maximum Transfer Unit) :--

If user wants to send the 700MB file. That will not send entire 700MB file in one go. Segment will be
created. CRC code will be attached & forward it. Maximum size of data can send in one segment called
MTU (Maximum transfer unit). How much data can send in one segment id depend upon the
prospective of technology.
1. In Ethernet & serial technology as per there prospective size of MTU would be 1500 bytes. It means
1500 byte ka tukda that is 1 segment.
This 1500 bytes means the information is coming from IP upper layer stack.

CRC DATA SIP DIP SMAC DMAC

38
 1500 bytes this will not include in 1500 byte because this is not
from IP upper layer stack.
2. As per wire prospective MTU size is 1518/19 bytes.
3. There may be some application include there header in frame. This makes frame bulky. This type of
frame called Jumbo or Bulky frame. In this situation MTU would be 1564/99 Bytes.
4. In Ethernet technology more than 1 GB & above MTU size would be 9000 Bytes.

7.7

-- : The actual collision detection is Switch or PC:--

When two frames are send on wire at a same instant of 1500 Bytes they will collide. They will
collide. They will collide means size of frame will get change.
As per given diagram suppose 2 frames of 1500 bytes get collided on wire. It change the
sequence of frame also CRC code will not match. Here these two frames get convert into 3 frames. May
be like 1/3 is 1160 bytes, 2/3 is 1800 bytes, 3/3 is 40 bytes, respectively.

1160 bytes 1800 bytes 40 bytes

1500 bytes 1500 bytes

Switch

Frame

PC 1 PC 2 PC 3 PC 4

AAA BBB CCC DDD

10.0.0.1/24 10.0.0.2/24 10.0.0.3/24 10.0.0.4/24
In actual collision detection in Switch or PC it will not check the CRC code always. 1st it will check the
size of frame. Because if every time Switch & PC will check the CRC code it will take more processing
time. If it found that frame size is not as per MTU it will assume that frame is collided & it will discard
the frame.

Collided frames are called :--

A. RUNT :- If size is less than 64 Bytes.
B. Giant :- If size is more than port MTU.
Why less than 64 Bytes frame called RUNT??
Ans :- Because minimum size of header is 64MB. Header means address of frame.

39
 As per given diagram when Switch or PC will receive frame 3/3 which is less than 64 bytes. It will
discard the frame assuming as RUNT frame. When Switch or PC will receive frame 2/3 which is 1800
bytes. It will discard the frame assuming as Giant frame.
But when Switch or PC will receive frame 1/3 which is 1160 bytes. It will treat as a normal frame
before accepting this frame it will check CRC code. As this was collided frame CRC code would not be
match. Then this frame will also discard.

In your data communication because of some application if size of frame gets change & making
it jumbo or baby jumbo frame then communication will not happen. Because MTU is 1500 Byte & size of
jumbo or baby jumbo frame would be more than 1500 bytes.

Solution :--
If your system is receiving Jumbo or baby jumbo frame then you need to by Switches which can
allow you to forward this kind of jumbo or baby jumbo frame. This type of Switches will allow you to
change the size of MTU in switch configuration. If you want to change the MTU in Cisco made switch
which support to forward jumbo or baby jumbo frame ------- You will go in port ................ .....
interface 0/a MTU 1599. After this it will consider normal frame to jumbo or baby jumbo frame.

7.8
There are some Switches available in markets that have different MTU for every port. It means
there is one Switch having 10 ports. In which 8 ports MTU is 100MB & remaining 2 ports MTU is 10GB.
This type of high band width ports called uplink port. The use of up linking port is to do up linking with
other switch or servers.

1) On uplink port many users traffic can transfer at time.

2) Uplink port is used to communicate with multiple Switch or server.
3) With the help of uplink port multiple systems can communicate at same time.

In below diagram port no. 1 & 5 is uplink port with the MTU of 10 GB. Remaining port 2, 3 & 4 MTU is
100MB.

Server Switch

1 2 Switch 3 4 5

40
PC 3
PC 1 PC 2
So it will make difficulty to communicate with in port no. 1 & 2 because MTU of both ports is different.
With port 1 it can transfer the data of 10 GB at time, but port to could not able to accept this much data
at time. Because port 2 MTU is low comparing to port 1 MTU.

Solution :--

There are two solution to form communication between higher port MTU to lower port MTU :--

1) Switches have fragmenting capability. When Data want to transfer from higher port MTU to
lower port MTU, Switch will fragment the data & then send it as per lower port MTU size.
2) Application may have capacity to send trace packet. That will learn path MTU & use lowest MTU
of path to do communication on that port.

7.9

--: Kahani me Twist :--

ARP Table
10.0.0.1 ==AAA
DATA SIP DIP SMAC DMAC

Routing Table
Nic 1 == 10.0.0.1/24

1 2 Switch 5 6

41

PC 4
 PC 1 PC 2 PC 3

AAA BBB CCC DDD

10.0.0.1/24 10.0.0.2/24 20.0.0.3/24 20.0.0.4/24

If user AAA wants to ping 10.0.0.2 It will create frame like --

DATA SIP DIP SMAC DMAC

In data :-- May I know your network layer status........ SIP :-- Source IP. It will capture from routing table,
Layer 3 table. (10.0.0.1) .............DIP :-- It will capture from command. (10.0.0.2)
But Kahani me Twist Before creating frame it will check with the help of routing table that can I
reach 10.0.0.0 network then only create frame. If it is not reachable it will discard the frame.
Here it will check in routing table that there is one IP 10.0.0.1 who belong to 10.0.0.0 network &
destination IP is 10.0.0.2 also belong from same 10.0.0.0 network so it will create frame.

BUT now if AAA user wants to ping 20.0.0.4 it will create frame like --

DATA SIP DIP SMAC DMAC

As Data & SIP will capture as per above mentioned process.

DIP :-- It will capture from command. (20.0.0.4)
But Kahani me Twist Before creating frame it will check with the help of routing table that can I
reach 20.0.0.0 network then only create frame. It is not reachable so it will discard the frame.
Here it will check in routing table that there is one IP 10.0.0.1 who belong to 10.0.0.0 network &
destination IP is 20.0.0.4 is not belong from same 10.0.0.0 network so it will not create frame.
Punch line :-- 8.1If frame is not reachable to destination IP. It will discard the frame. But if it is not aware
the destination MAC it will learn MAC address by using ARP broadcast.
8th lecture 14th Oct 2012
-- : Gateway :--

By default computer can communicate within same subnet (network). If you want to get away
from your network then you need a gateway device. By default Gateway means Router or Proxy server.
Router routes between the networks. Proxy server use demon software which help them to route in
different subnet (network).

PC 1 ARP Table RRR E0 E1 RRR Routers routing table

Route
Route
rr
42
 10.0.0.1 ==AAA 10.0.0.10/24 20.0.0.10/24 C 10.0.0.10/24 Directly
10.0.0.10 = RRR connected E0
C 20.0.0.10/24 Directly
PC 1 Routing Table connected E1
Nic 1 == 10.0.0.1/24
Dfg. 10.0.0.10

1 2 3 Switch 4
5 6

PC 1 PC 2 PC 3 PC 4

AAA BBB CCC DDD

10.0.0.1/24 10.0.0.2/24 20.0.0.3/24 20.0.0.4/24
Dfg: 10.0.0.10 Dfg: 10.0.0.10 Dfg: 20.0.0.10 Dfg: 20.0.0.10
Routers ARP table
10.0.0.10 == RRR DATA SIP DIP SMAC DMAC
20.0.0.10 == RRR Ping 10.0.0.1 20.0.0.4 AAA RRR
20.0.0.4 == DDD

Can I give default gateway address as 10.0.0.10 to DDD user who’s IP is 20.0.0.4???

Gateway device rule :-- 8.2

 By default computer can communicate in same subnet (network).
 Your computer IP & gateway should be in same subnet then only you can take a help of gateway
to communicate with other network.
If your PC & Gateway are not in same subnet (network) they will not able to communicate with
Each other then how can in this situation gateway will help you to communicate with other network.
That’s why you cannot give default gateway address as 10.0.0.10 to DDD user who’s IP is
20.0.0.4

If user AAA wants to ping 20.0.0.4 it will create frame like –

DATA SIP DIP SMAC DMAC

10.0.0.1 20.0.0.4 AAA RRR

43
In Data :-- May I know your network layer status
SIP :-- Source IP. It will capture from routing table, Layer 3 table. (10.0.0.1)
DIP :-- It will capture from command. (20.0.0.4)
As soon as it found that SIP & DIP from different network computer will discard the frame.
Before discard the frame it will check that if we cannot reach 20.0.0.4 directly do we have any Gateway
which will help to reach this network. With the help of own (AAA) routing table computer will found that
we have one gateway that is 10.0.0.10 in routing table. In this situation it will not discard the frame it
will continue. Next is
SMAC :-- It will take from own ARP table.
DMAC :-- Here it will take gateway’s MAC that is RRR. Because Gateway is doing help to reach AAA to
other networks DDD.

Punch line :-
 If SIP & DIP are in different network’s DMAC will be gateway’s MAC.
 Computer will decide whether data will switch or route.

8.3

DATA SIP DIP SMAC DMAC

10.0.0.1 20.0.0.4 AAA RRR
When this frame will come to switch. Switch will forward this frame to Router with the help of own
MAC table. When this frame receive to Router. It will check layer 2 information that is DMAC. Where
you want to go? Ans . RRR. Router will accept the frame. Keep layer 2 information side & forward layer 3
information ahead. Then again it will ask where you want to go. Ans. 20.0.0.4 Router will say but I am
10.0.0.10 you are not for me. Router will not discard the frame immediately.
Because Router routes between the network. It will check own routing table can we reach
20.0.0.4? (Here it will specify the DIP not 20.0.0.0 network that will check in PC) Ans. NO, But there is
one interface E1 with us which belong to same network 20.0.0.10 so router will modified the frame &
forward it to that network with E1 interface. Frame will modify in every hope in Ethernet technology.
While modify the frame SMAC & DMAC will gate change but SIP & DIP will never get change for end to
end IP traceability.
Router will modify the frame like ---------

DATA SIP DIP SMAC DMAC

10.0.0.1 20.0.0.4 RRR DDD
Router will check the MAC address of 20.0.0.4 by his own ARP table. If it is not available will send
ARP request (means send IP request for MAC) & learn MAC address. If it available. He will directly
forward to DDD.
 Router routes between the networks.
 Router takes participation in communication, that’s why he can modify the frame.
 Switch will not take participation in communication, that’s why Switch cannot modify the frame.
 Router can broadcast the frame. Switch does not support broadcast.
44
  We need to configure the IP address on Routers port because Router takes participation in
communication.
 But we will not configure the IP address to switch ports, because Switch facilitates
communication. Switch will not take participation in communication.

8.4
-- : Router :--
1) Router is an intelligent device.
2) As soon as Router receives a packet on his port. It will open layer 3 information read IP address,
Refers routing table & will take forwarding decision. (Layer 1 we called data on layer 2 frame &
on layer 3 packet)
3) IP address is a layer 3 address, routing table is a layer 3 table, and hence Router is layer 3
devices.
4) Router will route the packet only if it has route to reach that network.

Routes in routing table can be populated in 3ways :--

1) Directly connected networks route will learn automatically in routing table.
2) Administrator can make static entries in routing table.
3) Dynamic routing protocol can be use to learn routes & can be stored in routing table.

VIMP :--
Router routes between the network & Switch switches within the subnet.
Because Router routes between the networks hence every port of router should be in different
subnet (network). No two ports of router can belong to same subnet (network).
Every port of router is a member of separate collision / Broad cast domain
Router is a multiple collision domain & Broad cast domain device.
Every upper layer device can also do lower layer functions. Router is a layer 3 device but it can
also perform layer 2, Layer 1 functions.
Multiple ports of router can have same MAC address or multiple MAC addresses depend upon
manufacturer to manufacturer.
8.5 broad cast
When router received broadcast packet on his port it will block it. (Router break
domain). But router can create broadcast because it takes participation in communication.
Packet forwarding between two PC connected with two different router --

Routing Table (AAA) Routing Table (BBB)

NIC 1 ==10.0.0.1 /24 NIC 1 == 30.0.0.1 /24
Dfg: 10.0.0.10 Dfg: 30.0.0.10

ARP Table (AAA) ARP Table (AAA)

10.0.0.1 == AAA 30.0.0.1 == BBB
10.0.0.10 == RRR 30.0.0.10 = SSS
A
AT
SIP

45
 1
0.0
10
DI

.
DA BBB

P
1

.
AAA TA

AC

0.0
C

SM

30
10

.
A
10.0.0.1/24 .0. 30.0.0.1/24

.
0.

M
1

S
Dfg: 10.0.0.10 Dfg: 30.0.0.10

D
30

SS
S IP .0.
0.

B
1

BB
DIP AA
A
SM RR
AC R
1 Switch 2
DM
2 Switch 1
AC
Switch 1 MAC table Switch 2 MAC table
1 == AAA No MAC address will use in serial port 1 == BBB
2 == RRR 2 == SSS
DATA 10.0.0.1 30.0.0.1
10.0.0.10 E0/0 E0/0
SIP DIP
S0/0 30.0.0.10
RRR Route
Route 20.0.0.1/24 SSS
Rout
Rout
rr S0/0 er
er
20.0.0.2/24

RRR Routing Table SSS Routing Table

C 20.0.0.1 /24 Directly connected S0/0 C 20.0.0.2 /24 Directly connected S0/0
C 10.0.0.10 /24 Directly connected E0/0 C 30.0.0.10 /24 Directly connected E0/0

Static 30.0.0.0 /24 -- >> 20.0.0.2 Static 10.0.0.0 /24 -- >> 20.0.0.1

In Given Diagram :--

If user AAA wants to ping 30.0.0.1 it will create frame like –
In Data :-- May I know your network layer status
SIP :-- Source IP. It will capture from routing table, Layer 3 table. (10.0.0.1)
DIP :-- It will capture from command. (30.0.0.1)
As soon as it found that SIP & DIP from different network computer will discard the frame.
Before discard the frame it will check that if we cannot reach 30.0.0.1 directly do we have any Gateway
which will help to reach this network. With the help of own (AAA) routing table computer will found that
we have one gateway that is 10.0.0.10 in routing table. In this situation it will not discard the frame it
will continue. Next is
SMAC :-- It will take from own ARP table.
DMAC :-- Here it will take gateway’s MAC that is RRR. Because Gateway is doing help to reach AAA to
other networks DDD. If SIP & DIP are in different network’s DMAC will be gateway’s MAC.

So AAA will create frame like -------

DATA SIP DIP SMAC DMAC

10.0.0.1 30.0.0.1 AAA RRR 46
 When this frame will come to switch 1 Switch will forward this frame to Router with the help of
Own MAC table. When this frame received to Router. It will check layer 2 information that is DMAC
where you want to go? Ans . RRR. Router will accept the frame. Keep layer 2 information side & forward
layer 3 information ahead. Then again it will ask where you want to go. Ans. 30.0.0.1 Router will say but
I am 10.0.0.10 you are not for me. Router will not discard the frame immediately.
Because router routes between the network. It will check own routing table can we reach
30.0.0.1? Ans. NO, if route is not available in routing table router will discard the frame. Here we will
suppose that there is one static route entry is available in RRR routing table (Static 30.0.0.0 /24 -- >>
20.0.0.2). It means if you want to reach 30.0.0.0 network send traffic to 20.0.0.2 now router will check
by own routing table how to reach 20.0.0.2???? Ans. 20.0.0.1 is directly connected with interface so/0.
Through that we can reach 20.0.0.2 then it will forward this frame to 20.0.0.1 (Interface s0/0)

Here 20.0.0.1 & 20.0.0.2 is connected with Serial technology. Hence frame will modify again.
There will be no use of MAC address in serial technology because it is point to point technology. (Tu bhej
raila me sun raila, me bhej raila tu sun raila to kahe ki syndrela) MAC is use in Ethernet technology
because Ethernet is multi-access technology. Many systems are connected in Ethernet technology at
time in one network. To identify them MAC address is required. There will be no MAC address while
packet is moving from serial technology. There will be pads. Pads means buffers.

So router RRR & SSS is connected with Serial technology. Hence frame will modify like ---

DATA 10.0.0.1 30.0.0.1

SIP DIP

When this frame received to SSS interface s0/0 (20.0.0.2) it will check DIP (30.0.0.1).
By own (SSS) routing table this packet will forward to E0/0 (30.0.0.10)
Here Frame will modify in every hope of Ethernet technology. While modify the frame SMAC & DMAC
will gate change but SIP & DIP will never get change for end to end IP traceability.

SSS Router will modify the frame like ---------

DATA SIP DIP SMAC DMAC

10.0.0.1 30.0.0.1 SSS BBB
Router will check the MAC address of 30.0.0.4 by his own ARP table. If it is not available will send
ARP request (means send IP request for MAC) & learn MAC address. If it available. He will directly
forward to BBB.

Response frame will also revert in same way.

8.6
47
 --: OSI Layer :--
OSI layer is frame work (dhacha) of networking standards. It will not explain how your
technology will work? Or how upper layer protocol will work? OSI layer explains that if you innovate
anything related to networking or innovate any protocol related to networking then how to open its
standard.
OSI layer teach us how to open the standard of any technology layer by layer. OSI layer is layer
of standards.

48