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carrier extension

In order to achieve a collision domain propagation of 200 m for Gigabit Ethernet, the CSMA/CDcollision method was improved. This addition was necessary because Ethernet frames with the minimum frame length of 64 bytes were already completely fed into the transmission medium before the transmitting data station detected a collision.

For this reason, both the frame length and the slot time were increased for Gigabit Ethernet, which is not standard-compliant. The frame length was increased from 64 bytes to 512 bytes, which did not affect the minimum frame length of 64 bytes. Frames smaller than 512 bytes are padded to this value. For this purpose there is a special data field, Carrier Extension, which follows the cyclic block check(CRC) data field.

Ethernet frame with Carrier Extension for Gigabit Ethernet

Ethernet frame with Carrier Extension for Gigabit Ethernet

Padding to a minimum frame length of 512 bytes affects the performance of small data packets. To compensate for this, there is a so-called packet bursting with which servers, switches and other Ethernet components can send bursts of small data packets and thus make better use of the available bandwidth.

Englisch: carrier extension
Updated at: 10.10.2012
#Words: 173
Links: indium (In), order, collision domain, Gigabit Ethernet (GbE), carrier sense multiple access (CSMA)
Translations: DE

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