[e2e] TCP-SYN and delayed TCB allocation

[Joe Touch]

Alok Dube wrote:

> Hi,
> 
> Maybe this has been asked several times, but i am taking the "path of least
> effort" and asking :-)
> 
> Is the TCB allocated on TCP done
> A)  immediately after receiving the SYN?
> 
> or
> 
> B) has it been modified that it is now done after the 1st ACK?
> 
> if not, any reason why not B? we would so the same if we had a
> "NAT/Firewall" with delayed binding etc

If B), where do you put the data that could have been sent in the SYN? 
I'm not sure you can ACK the SYN without ACKing the data therein (though 
you don't deliver it until receiving the ACK and transitioning to 
ESTABLISHED)...

Joe