Abstract
- Stands for Carrier Sense Multiple Access
- Essentially, multiple hosts share the same carrier to communicate
Carrier
Refers to any shared transmission medium.
Copper wire in the case of Ethernet. Air carrying radio waves for Wi-Fi.
Multiple access
Refers to the ability of many computers to send data over the same carrier simultaneously
How do computers know if they should process the incoming data?
When one computer sends a piece of data to another computer, all other computers sharing the same carrier also receive the data. This is resolved using the MAC Address. A computer processes the data only if the recipient address in the data matches its own MAC address.
Collision
- Occurs when more than one computer on the same collision domain (sharing the same carrier) sends data simultaneously. This causes data on the carrier to become corrupted, requiring a retransmission. This phenomenon is also known as packet loss
- Collisions can be detected by monitoring the signals on the carrier.
Important
The more devices connected to the same network, the higher the likelihood of collisions. This reduces the network’s performance due to frequent retransmissions.
To mitigate this, a bridge device can be used to divide a network into multiple smaller networks (subnetworks). This reduces the number of devices in each network, thereby lowering the likelihood of collisions.
Another way to handle it is to use exponential backoff algorithm.