[ih] Why FTP uses two ports?

[Bernie Cosell]

On 21 Jun 2012 at 10:03, Jack Haverty wrote:

> The decision was made to adopt the in-band approach. There were then a
> lot of details to work out, especially with respect to the "Urgent 
> Pointer" mechanism of TCP. While it was straightforward to define the 
> details of Urgent in the TCP protocol, it was much less clear how the 
> programs at either end of the connection should behave. E. G., when 
> you are notified that there is urgent data further downstream, but your
> own buffers are full, what do you do - discard everything until you get
> the urgent data?

Off topic, but wasn't there a mechanism like this in telnet?  I don't 
remember the details any more but I thought there was a way to tell the 
reciver "I've put a datamark in the data stream, throw everything away 
until you get to it".  I recall working with Bob Clements [I think] to 
get that to work between the TIP to TENEX [so if you hit control-C it'd 
dump the other input you'd "typed ahead"]

  /Bernie\

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Bernie Cosell                     Fantasy Farm Fibers
mailto:bernie at fantasyfarm.com     Pearisburg, VA
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