not sure ESTABLISHED TCP traffic will have ACK flag setalways...

Grant Taylor gtaylor at
Sun Apr 10 07:09:55 CEST 2005

> Grant
> Wow!  Thanks again.  You cleared up the last missing piece about ACKs!
> So the slow side can ACK multiple sequence numbers with a single
> packet.  Likewise, the /fast/ side can send multiple ACKs for
> the same repetitive sequence number.  That makes perfect sense.
> Now I believe that TCP packets can all have ACKs set on an
> ESTABLISHED connection.
> Chris
> P.S. BTW, I'm curious how you knew this level of great info.  Did you
> carefully read through RFC 793?  That was jam packed with info but
> hard to digest fully.

No, I cant say as I recall reading RFC 793 in particular, though I do read a LOT of RFC pertaining to what I do, I'm a systems administrator / consultant, so I need to know a lot about email (SMTP), DNS, www (HTTP), etc.  I spend a lot of time helping others get their system up to speck thus I've run across a lot of not quite up to spec but close enough to work *most* of the time.  I get called when it does not.  If ever I run across things that I don't know about (and it happens more than you might think) I turn to RFC, Google (this is a REALLY BIG ONE), and peers in the industry on mail lists like this one.  It's not what you know, it's who you know to ask.  :)

Grant. . . .

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