Computer Network-2

1. Computer Networks-2
Imranul Hasan
Greenwich University, UK

2. LAN Components
Network Interface Cards (NIC)
Network devices
Hub
Repeater
Bridges
Switch
Router
Networking media
Computers
Peripheral devices

3. Network Interface Card
 Also called Network Adapter
 Connects a host to a network
medium
 Contain unique MAC Address
to control data communication

4. Network Card
o Network Card
with both BNC
(left) and RJ-45
Port (right).

5. Network Card
Installing a PCI Network Interface Card in Motherboard

6. Network Card
o Connecting RJ-
45 Connector
with RJ-45 Port

7. RJ-45 Connector

8. RJ-45 Jack
Front View Top down View

9. Network Card
PCI Wireless NIC
PCMCIA = Personal Computer Memory Card International Association

10. Network Card
o PCMCIA network
interface card are used
in laptop computer. There
are three kind of PCMCIA:
o Some cards have an RJ45
connector built into the card
o Some used an extension
cable to connect the RJ45
to the network media
o Some are wireless PCMCIA
PCMCIA = Personal Computer Memory Card International Association

11. Modem
 A modem, or modulator-demodulator, is a device
that provides the computer with connectivity to a
telephone line.
 A modem converts data from a digital signal to an
analog signal that is compatible with a standard
phone line.

12. Repeaters
 Strengthens signal to send over
long distances
 Can regenerate and retime network
signals at the bit level

13. Repeaters

14. Hub
 Is a device that centralizes
network traffic through a
single connection point.
 Multi-port repeaters with 4 to
24 ports (typical repeater
usually has 2 ports)
 Data on one port is
electrically repeated on all
other ports
 Converts the network to Star
topology

15. Hub
o Number of PC
depends on the
number of ports
available on the hub

16. Classification of Hubs
Active hub:
 which regenerates and transmits the signal
 is also called as multiport repeater
 requires electrical power to run
Passive hub:
 acts as a connection point
 does not amplify or regenerate signals
 does not require electrical signals

17. o Connection by which a local area network may be
linked to other local area networks or to larger
networks.
o The way through which computer connects to other
LAN or Internet
Gateway

18. o A device that connects
two local-area networks
(LANs), or two segments
of the same LAN that use
the same protocol, such
as Ethernet or Token-
Ring.
o A device that connects
multiple network
segments
o Traffic from one network
is forwarded through it to
another network.
Bridge

19. Bridges

20. Bridges Segmenting Network

21. How Bridges work?
 Each Bridge holds a Bridge table
 On receipt of a frame, destination MAC address is
looked up in the table
 If destination device is on
 Same segment - do not send, known as Filtering
 Different segment - forward to appropriate one
 Unknown segment - forward to all except the received one,
known as Flooding

22. How Bridges Work?

23. o Switch: a device that allocates traffic from one
network segment to certain lines (intended
destination(s)) which connect the segment to
another network segment.
o Unlike a hub a switch splits the network traffic and
sends it to different destinations rather than to all
systems on the network.
o It is often used to replace network hubs. A switch is
also often referred to as an intelligent hub.
Switch

24. Switch
 Sometimes called multi-port bridge
 More sophisticated than a bridge
 Alleviates congestion and reduce
traffic

25. Switch

26. Micro-segmentation within Switch

27. Switching Table

28. Advantages of Switch
 Switches operate at much higher speeds than hubs
 Allows multiple users to communicate at the same
time through Virtual circuits and dedicated network
segments
 Creates Virtually Collision free environment
 Improves network speed, bandwidth and
performance
 Very cost effective since the hardware and cables in
place can be reused

29. Router
 A device that forwards data packets
along networks. A router is
connected to at least two networks,
commonly two LANs or WANs or a
LAN and its ISP’s network. Routers
are located at gateways, the places
where two or more networks
connect. Routers use headers and
forwarding tables to determine the
best path for forwarding the packets,
and they use protocols such as
ICMP to communicate with each
other and configure the best route
between any two hosts.
 Very little filtering of data is done
through routers.

30. o The network contains:
o Cable/DSL Modem to
provide internet
connectivity;
o Wireless access point
with RJ-45 ports to
provide internet to more
PC through Cable and
radio signal;
o PC with Wireless LAN
Card to communicate
with Wireless Access
Point through radio
signal;
o PC with RJ-45 LAN
Card to connect with
Access Point through
cable.
A Small Home Network

31. IP address
 It is a 32-bit address used to identify a node on an IP
internetwork.
 Each node on the IP internetwork must be assigned a unique IP
address, which is made up of the network ID, plus a unique host
ID.
 This address is typically represented with the decimal value of
each octet separated by a period (for example, 192.168.7.27).
 You can configure the IP address statically by assigning fixed IP
address or dynamically through DHCP.
 The IPv4 (IP version 4) provide 32 bit addressing mechanism
whereas IPv6 provide 128 bit addressing mechanism

32. Classes of IP Address
 There are 5 classes of IP address –
 Class A: The first octet value ranges from 1 to 126;
 Class B: The first octet value ranges from 128 to 191;
 Class C: The first octet value ranges from 192 to 223;
 Class D: The first octet value ranges from 223 to 239. It is used
for multicasting and not for use in host addressing;
 Class E: The first octet value ranges from 240 to 255. This
group of IP is kept reserved and not available to use in host
addressing;
 The Class A, B and C address are available for host addressing
with some exceptions
 The 127 of first octet is not available for host addressing.

33. IP Address Bit Patterns

34. Identifying Classes
 Classes can be identified by examining the value in the first octet
of IP address
 Ranges of values in the first octet for different classes :
 Class A : 0 – 127 N . H . H . H
 Class B : 128 – 191 N . N . H . H
 Class C : 192 – 223 N . N . N . H

35. Network Address and Broadcast Address
 Network address :
 Used to identify the network
 Denoted by values in the network part and all 0’s in the host part
 Broadcast address :
 Used to address all the hosts in a single network
 Denoted by values in network part followed by all 1’s in the host
portion
 Examples:
 IP address: 192.168.20.3
 Class : C
 Network Address: 192.168.20.0
 Broadcast Address: 192.168.20.255
 IP address: 185.23.5.1
 Class : B
 Network Address: 185.23.0.0
 Broadcast Address: 192.168.255.255

36. Subnet Mask
 Subnet Mask is used to tell devices which part of the IP address
is network number (including subnet) and which part is the host
 Uses the same format as IP addressing i.e. 32 bit long and
divided into four octets
 Have all 1’s in the network portion and all 0’s in the host portion

37. Default Subnet Masks
 Class A :
- N. H. H. H
- 11111111.00000000.00000000.00000000
- 255 . 0 . 0 . 0
 Class B :
- N. N. H. H
- 11111111.11111111.00000000.00000000
- 255 . 255 . 0 . 0
 Class C :
- N. N. N. H
- 11111111.11111111.11111111.00000000
- 255 . 255 . 255 . 0

38. Thank You!!