1.
1

2.
Hub
• It is a Physical layer device (Layer 1)
• It is Dummy Device
• It works with 0’s and 1’s (Bits)
• It works with broadcasting
• It works with shared bandwidth
• It is has 1 Broadcast Domain and 1 Collision Domain
• Collisions are identified using Access Methods called
CSMA/CD and CSMA/CA
2

3.
Broadcast Domain & Collision Domain
• Broadcast Domain
Set of all devices that receive broadcast frames
originating from any device within the set.
• Collision domain
In Ethernet, the network area within which frames that
have collided are propagated is called a collision
domain.
• A collision domain is a network segment with two or
more devices sharing the same bandwidth.
• Repeaters and hubs propagate collisions, LAN switches,
bridges, and routers do not.
3

4.
Types of Hubs
• Active Hubs uses power supply and
regenerates the
data (i.e.) strengthens the
signals in case of disturbances.
• Passive Hubs doesn’t use power supply and it will not
not regenerates the data (i.e.) strengthens the signals in
case of disturbances. It is used only to share the physical
media
• Intelligent Hubs are sometimes called as smart hubs.
These devices basically function as active hubs, but also
include a microprocessor chip and diagnostic capabilities
and are useful in troubleshooting situations.
4

5.
Switch
• It is Datalink layer device (Layer 2)
• Its is An Intelligent device
• It works with Physical addresses (i.e. MAC addresses)
• It works with fixed bandwidth
• It works with Flooding and Unicast
• It has 1 Broadcast domain and Number of Collision
domains depends upon the number of ports.
• It maintains a MAC address table
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6.
Types of Switches
• Manageable switches
On a Manageable switch an IP address can be assigned
and configurations can be made. It has a console port .
• Unmanageable switches
On an Unmanageable switch configurations cannot be
made, an IP address cannot be assigned as there is no
console port.
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7.
Bridge Vs Switch
Bridge
• Bridges are software
based
• Bridges have lesser
no. of ports
• Generally used for
Switch
• Switches are hardware
based
• Switches have higher
no. of ports
• Generally used for
connecting two
connecting single
different topology
topology (Segment)
(Segment)
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8.
Router
• It is a Network layer device (Layer 3)
• Its is an Intelligent device
• It works with Logical Addressing (i.e. IP,IPX,AppleTalk)
• It works with Fixed bandwidth
• Number of Broadcast domains depends upon the
number of ports and Number of Collision domains
depends upon the number of ports.
8

9.
How many Broadcast &
Collision Domains
E0
E1
9

10.
Broadcast Domains
E0
E1
10

11.
Collision Domains
E0
E1
11

12.
Cisco’s Hierarchical Design Model
Cisco divided the Switches into 3 Layers
• Access Layer Switches
Switches Series : 1900 & 2900
• Distribution Layer Switches
Switches Series : 3000 & 5000
• Core Layer Switches
Switches Series : 7000, 8000 & 10,000
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13.
Access Layer Switch
13

14.
Switching Mode
Three types of Switching Mode :
• Store & Forward
• Fragment Free
• Cut through
14

15.
Store & Forward
• Store and forward switching pulls in the whole frame into
the port buffer, checks the CRC and then switches the frame
if its error free
• All switches support Store and Forward
• A Default switching method for distribution layer switches.
• Latency : High
– Latency is the period of time from when the beginning of a frame
enters to when the end of the frame exits the switch.
– Latency is directly related to the configured switching process
and volume of traffic.
15

16.
Store & Forward
Whenever, a Frame is received by the Switch
Whenever, a Frame is received by the Switch
It will store the Complete Frame
It will store the Complete Frame
It will run CRC on Complete Frame
It will run CRC on Complete Frame
If, Error
If, Error
Contact Source
Contact Source
Transport Layer
Transport Layer
If, No Error
If, No Error
Check MAT
Check MAT
If, Entry
If, Entry
is there
is there
Unicast
Unicast
If, Entry
If, Entry
is not
is not
there
there
Flooding
Flooding
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17.
Fragment Free
• It is also referred to as Modified Cut-Through
or Runtless switching method.
• The switch checks the first 64 bytes of a frame before
forwarding it for fragmentation, thus guarding against
runt frames.
• 64 bytes is the minimum legal size of an Ethernet frame.
Frames smaller than 64 bytes are called Runt frames.
• Faster compared to Store and Forward but could switch
corrupt or bad frames.
• A Default Switching method for access layer switches.
• Latency : Medium
17

18.
Fragment Free
Whenever, a Frame is received by the Switch
Whenever, a Frame is received by the Switch
It will store the Frame
It will store the Frame
It will run CRC on 64 byte of Frame
It will run CRC on 64 byte of Frame
If, Error
If, Error
Contact Source
Contact Source
Transport Layer
Transport Layer
If, No Error
If, No Error
Check MAT
Check MAT
If, Entry
If, Entry
is there
is there
Unicast
Unicast
If, Entry
If, Entry
is not
is not
there
there
Flooding
Flooding
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19.
Cut Through
• The switch reads only the first part of the frame
(i.e) the destination MAC address before forwarding
• It is faster compared to store and forward but the
biggest Problem is it may be switching bad frames.
• Although this occurs infrequently and the destination
network adapter will discard the faulty packet upon
receipt
• A Default switching method for the core layer switches
• Latency : Low
19

20.
Cut through
Whenever, a Frame is received by the Switch
Whenever, a Frame is received by the Switch
Check MAT
Check MAT
If, Entry
If, Entry
is there
is there
Unicast
Unicast
If, Entry
If, Entry
is not
is not
there
there
Flooding
Flooding
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21.
External of Switch
Catalyst 1900
10BaseT
1
2
3
4
5
6
7
8
10 mbps Ports
9
10
11
12
A
B
Fast Ethernet
100 mbps Ports
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