What is the Switch?
This is the most common devices for interconnecting the local area network. The Switch provides the bridging functionality with greater efficiency and act as a multipoint bridge to connect devices in a local area network. Switch looks each data unit it received and determines from a physical address that is the MAC address, for which device the packet is intended and Switch out the packet towards that device. The Switch normally has a buffer for each link to which it is connected. When Switch receives a frame, it stores the packet in the buffer of the receiving link and checks the address to find the outgoing link. If the outgoing link is free means there is no chance of collision, the switch send the frame to that particular link.
The Switch responsible for multiple functions such as filtering, flooding and sending frames. It uses the destination address of the individual frame to sending the frame outside link. Switches operate at the Data link layer of the OSI model. Bridge and the Switches read each and every frame as it passes through the network. The layer 2 device then put the source hardware address in the filter table and keeps the track of the port on which the frame was received. By this information machine can determine the location of the sending device.
When a Switch interface receive a frame having destination hardware address that is not available in the device’s filter table ,it will forward the frame to all connected segments, if the unknown device replies to this forwarding action, the switch updates its filter table regarding that device location. But if the destination address of the transmitting frame is the broadcast address, the switch will forward all broadcast to every connected segment. The biggest benefit of using switches instead of hubs in the internetwork is that each switch port has its own collision domain and the hub creates one large collision domain.
In the Switches each devices on every connected segment can transmit simultaneously and hubs only allow one device to communicate at a time. Switches are based on two different categories-The first one is Store and forward, in which Switch stores the frame in the input buffer until the whole packet has arrived. Second is Cut through, in which the Switch is forward the packet to the output buffer as soon as the destination address is received.
No related posts.