What is Network Switch
Switches
Switches are data-link layer devices that connect multiple LAN segments to
form a single network segment, Switches examine the data packets for source and
destination addresses. The switches then forward the data packet to the
appropriate destination. The forwarding of data only to the specified
destination enables you to conserve bandwidth. Bandwidth is the amount of data
that is transmitted in a specific amount of time.
Switches minimize the possibility of collisions of data
packets by reducing collision domains. Collision domains are the network
segments between two network devices. When two network devices simultaneously
try to transfer a data packet over the same route on the network, a collision
occurs. In such cases both devices stop transmitting data for a particular
time. They try to re-transmit the data after the specified time.
Switches reduce the collision domains using micro segmentation.
Micro segmentation is a technique by which the switches cut down the collision
domain into smaller segments. The final segment consists of only two nodes or
devices, the source and destination eliminating the possibility of a collision.
Cisco Switches
Cisco Catalyst 1900 Series Switch
Cisco Catalyst 2900 Series Switch
Cisco Catalyst 2940 Series Switch
Cisco Catalyst 2950 Series Switch
Cisco Catalyst 2960 Series Switch
Cisco Catalyst 2970 Series Switch
Cisco Catalyst 3500 Series Switch
Cisco Catalyst 3550 Series Switch
Cisco Catalyst 3560 Series Switch
Cisco Catalyst 3750 Series Switch
Cisco Catalyst 4000 Series Switch
Cisco Catalyst 4500 Series Switch
Cisco Catalyst 4900 Series Switch
Cisco Catalyst 5500 Series Switch
Cisco Catalyst 6500 Series Switch
Cisco Catalyst 8500 Series Switch
Cisco Catalyst G-L3 Series Switch
Types of Switches
Managed Switches
A switch is said to be a managed switch if it supports SNMP
(Simple Network Management Protocol). It allows you to set the communication
parameters as per your requirement to
control the network. A managed switch provides network statistics through SNMP.
The network statistics include the number of bytes and frames transmitted or
received and number of errors and port status on each port. Some managed
switches make statistics available on web server, which allows you to use a standard
browser to view the network status.
Unmanaged Switches
A switch is said to be unmanaged if it enables the Ethernet
devices to communicate. Once you connect the Ethernet devices to the unmanaged
switch, they start communicating. The switch has status LEDs that provide
feedback on the link activity.
Switching
There are three types of network switching
Cut through Switching
Forwards data packets as soon as the switch receives them.
Data packets consist of the header and data content. The header contains the source and
destination address for the data packet. When a network device receives the data packet, it validates the
data by comparing the checksum value. The checksum value is the number of bytes in the data packet.
Both the host and destination computers calculate this value. The device can calculate the checksum
of a packet only after the Complete packet is transferred. Therefore, the cut through switch may forward
a data packet with an incorrect checksum.
Store and Forward Switching
In the sore and forward switching, Performs a checksum on each data packet or data frame before
forwarding it. The store and forward switches wait for the data packet to
arrive before transmitting them. Therefore, the switches examine each packet
completely before sending them over the network. The store and forward switches
operate slower than the cut through switches. Store and forward switches
minimize the errors occurring due to improper packet forwarding.
Fragment Free
Switching
In fragment free switching, Checks first 64 bytes of data before forwarding the data
packet. The first 64 bytes of data is the most error-prone region within the
data packet. Collisions occur during the first 64 bytes of a data packet.
Fragment free switches provide a balance between cut through switches and store
and forward switches. Cut through switches emphasize more on speed than error
checking. Store and forward switches check the errors in the packet at the free switches offer error
checking for the first 64 bytes of the data packet and provide a latency period
of 60 microseconds. The latency period is the time taken by the data packets to
reach the destination computer.
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