[c-nsp] Full Duplex

Jay Hennigan jay at west.net
Wed Nov 19 19:05:30 EST 2014


On 11/18/14, 2:16 AM, M K wrote:
> Hi all , we were arguing about the full duplex FE interface and it's speedIs it true that this interface can handle 100Mbps send and 100Mbps receive at the same time? like it is 200Mbps ?

To be more precise, the throughput in either direction is limited to 100
Mbps but traffic can flow in both directions at the same time.

If you have an expressway with lanes in both directions and a speed
limit of 100 MPH, you don't call it a 200 MPH expressway.  (That's
full-duplex).

If you have a single-lane road with a speed limit of 100 MPH then you
can transmit at up to 100 MPH in one direction at a time. Attempting to
transmit in both directions at the same time results in what is referred
to as a collision. Collisions reduce throughput as the debris must be
cleaned up and then retried.

Salespeople have been known to refer to T-1 circuits as 3Mbits/s and
100Mbps full-duplex Ethernet as 200 Mbits/s. This is considered to be
nitrogen-rich organic fertilizer by those with clue.

--
Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV


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