Linux TCP/IP stack

[Rabeeh Khoury <rabeeh@xxxxxxxxxxxxx>]

Hi All,

I have noticed (using tcpdump and simple TCP client-server application)
that TCP frame are always sent with ACK flag even if the sender doesn't
receive new frames (i.e. it send the same Acknowledgment Number).

RFC 2581 (section 4.1) states that:
  "A TCP receiver MUST NOT generate more than one ACK for every
incoming
  segment, other than to update the offered window as the receiving
  application consumes new data"

According to the above statement it seems that LINUX TCP / IP violates this 
rule.

Thanks, 
Rami