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Re: Interframe gap

At 4:08 PM -0500 5/21/99, Denis Beaudoin wrote:
>Mark, The interframe gap is not to be used as processing time, this
>leads to problems like the 'tailgate scandal' where certain NIC cards
>could not see frames back-to-back because of IPG erosion on repeaters.
>The standard RX function can have the next RX frame on the event following
>CRS deassertion. Runout which you speak of (the time required for the device
>to complete its current rx operation before it starts the next rx) is
>a design issue not a standard issue.

It may be a design issue, but it is *precisely* the reason why the IFG was
included in the first place. There is a certain amount of housekeeping that
is performed between frames, and the IFG is there to provide some
"breathing room".

I agree that it was a mistake to assume, in a repeated LAN, that the
receiver would always see the full IFG as generated by a transmitter, but
it was NOT unreasonable to assume that there would be *some* IFG available
for housekeeping functions. It was never the intent of the standard to
require receivers to live with zero IFG. Yes, it is a design issue, but the
IFG supports a practical design.

Rich Seifert                    Networks and Communications Consulting
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