Suggest an editImprove this articleRefine the answer for “Why does a minimum frame size exist?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**The minimum Ethernet frame size** exists because of the collision detection mechanism (CSMA/CD) in classic Ethernet. **Key point:** a frame must be long enough (64 bytes) for the sender to notice a collision before finishing the transmission.Shown above the full answer for quick recall.Answer (EN)ImageThe minimum Ethernet frame size exists **because of the collision detection mechanism** in classic Ethernet. Briefly: **a frame must be long enough for the sender to have time to notice a collision**. --- ## Where this limitation comes from Early Ethernet networks used the **CSMA/CD** mechanism (Carrier Sense Multiple Access with Collision Detection): - several devices shared **one common medium** - they could start transmitting at the same time - this caused **collisions** --- ## The problem with a short frame If a frame is too small: - the device may **finish transmitting** - **before** the collision signal makes it back to the device In that case: - the sender considers the transmission successful - but the frame is actually **corrupted** - data is lost without anyone noticing --- ## Why a minimum size is needed The minimum frame size guarantees that: - the frame is transmitted **for long enough** - a collision (if one occurs) **has time to be detected** - the sender can: - stop the transmission - retry it later --- ## Why exactly 64 bytes For Ethernet: - **the minimum frame size is 64 bytes** - this is calculated from: - the maximum segment length - the signal propagation speed - the collision detection time If there is less payload data: - Ethernet **adds padding** - to reach 64 bytes --- ## What about now? Important for an interview: - On modern networks: - **switches** are used - **full-duplex** is used - there **are no** collisions But: - the minimum frame size **has stayed in the standard** - for compatibility and consistency --- ## What to remember - the minimum frame size exists **because of collisions** - it is tied to the **CSMA/CD** mechanism - it equals **64 bytes** - padding is used when there is not enough data --- ## Short version for an interview > **The minimum Ethernet frame size exists so that a transmitting device has time to detect a collision on a shared transmission medium; that is why the standard sets a minimum of 64 bytes.**For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.