[c-nsp] Full Duplex

[Chris Evans]

Marketing folks love to use half-duplex when speaking about backplane
fabric speed..  Typically they don't do that on the ports themselves,
typically..

On Wed, Nov 19, 2014 at 6:05 PM, Jay Hennigan <jay at west.net> wrote:

> 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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