Switch

Cisco Switch:

Ø  Provides centralized location to connect devices within the LAN.
Ø  It is the networking device.

Ø  All the computers are connected to a single switch through a cable with the help of Star Topology. 

Ø  Every device requires a single cable point-to-point connection between device and switch (Uses twisted pair, Optical Fiber or coaxial cable)

Ø  Without switch we can not build a Local Area Network in real production network

Ø  All the devices share data through switch.

Ø  Only that device is affected which has failed, rest of the devices can work smoothly.

Ø  Due to some technical reason, if the switch fails then the whole network is stopped because all the nodes depend on the switch.

Ø  The switches come with 4,8,12,16,24,28,48,52 port configurations.

Ø  The switches work at Data Link Layer (Layer-2) of OSI Reference Model.

Ø  The switches are intelligent device which maintain MAC Table (Consist of MAC Addresses of all devices present in the network and Port Numbers i.e. It will tell on which the device is connected)
Ø  It is also called Multi-port Bridge
Ø  Switches provide high-speed exchange
Ø  They provide dedicated communication between devices i.e. point-to-point communication

Ø  Types of Switches:

·       Unmanageable switches

·       Manageable Switches

Unmanageable switches

Ø  Plug and Play (Connect & Use)

Ø  No configurations and verification can be done

Ø  There is no Console port

Manageable Switches

Ø  Plug and Play (Connect & Use)

Ø  It has console port and CLI access

Ø  We can verify and modify configurations and can implement and test some advances switching technologies (VLAN, Trunking, STP)

Basic LAN Setup:

Ø  Connect 4 computers in the LAN using Switch

Ø  Configure IP Addressing on all PC using 192.168.1.0/24 network

Ø  Check connectivity between all the PC using ping command

Ø  Ethernet switches have three basic design architectures: store-and-forward switch, cut-through switch and hybrid switch

Store-and-Forward switch

Ø  It will wait until the entire frame has arrived prior to forwarding it.
Ø  This method stores the entire frame in memory.
Ø  Once the frame is in memory, the switch checks the destination address, source address, and the CRC.
Ø  If no errors are present, the frame is forwarded to the appropriate port.
Ø  This process ensures that the destination network is not affected by corrupted or truncated frames.
Ø  Sometimes referred to as buffering switch.

Cut-Through switch
Ø  It will begin forwarding the frame as soon as the destination address is identified.
Ø  The difference between this and Store-and-Forward is that Store-and-Forward receives the whole frame before forwarding.
Ø  Since frame errors cannot be detected by reading only the destination address, Cut-Through may impact network performance by forwarding corrupted or truncated frames.
Ø  These bad frames can create broadcast storms wherein several devices on the network respond to the corrupted frames simultaneously.

Hybrid switch

Ø  It integrates best features of store-and-forward (reliable frame transmission) and cut-through (Low latency) designs.

Ø  It is configured on a per port basis to change automatically from cut-through switch to store-and-forward switch if error rates exceed a user-defined threshold.

Ø  When error rates fall below this threshold, the switch reverts to cut-through switch.