[e2e] Are we doing sliding window in the Internet?

Joe Touch touch at ISI.EDU
Wed Jan 3 14:37:24 PST 2007



Lachlan Andrew wrote:
...
> As an aside, I thought of a nice hack which I think is within the
> letter of the standards, but well outside the spirit.
> 1. First packet, send a MSS
> 2. After the first ACK, send 2MSS worth of 1-byte packets
> 3. 1 RTT later, receive 1MSS worth of ACKs (ack'ing every second packet)
> 4. Without ABC, we now have a CWND of 500-1500 packets.
> 
> Could someone tell me if this is within the letter of the standards?

RFC1122, Sec 4.2.2.2:

            An application program is logically required to set the PUSH
            flag in a SEND call whenever it needs to force delivery of
            the data to avoid a communication deadlock.  However, a TCP
            SHOULD send a maximum-sized segment whenever possible, to
            improve performance (see Section 4.2.3.4).

Given the penchant for trampling SHOULDs, however, I wouldn't be
surprised to see someone implement the above and claim it to be compliant.

Joe

--
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Joe Touch
Sr. Network Engineer, USAF TSAT Space Segment

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