Re: [tcpm] I-D Action: draft-ietf-tcpm-1323bis-13.txt

[Joe Touch <[e-mail]>]

On 5/20/2013 12:13 PM, Yuchung Cheng wrote:
> I suggest removing all these texts;
>
> """If a non-<RST> segment is received without a TSopt, a TCP MAY drop
> the segment and send an <ACK> for the last in-sequence segment.  ""
> What's the point to ignore a perfectly fine data packet w/o TS-opt and
> respond a (DUP)ACK? the sender is probably may trigger fast recovery
> falsely. Responding ACKs is not going to make any forward progress  on
> buggy implementations or middle-boxes.
>
> """ A TCP MUST NOT abort a TCP connection if a non-<RST> segment is
> received without a TSopt. """
> TCP should abort only if it's truly in trouble. so let's not
> re-emphasize the general rule of trying to keep things going until the
> last minute.

The text currently says:

    Once TSopt has been successfully negotiated (sent and received)
    during the <SYN>, <SYN,ACK> exchange, TSopt MUST be sent in every
    non-<RST> segment for the duration of the connection, and SHOULD be
    sent in a <RST> segment (see Section 4.2 for details).  If a non-
    <RST> segment is received without a TSopt, a TCP MAY drop the segment
    and send an <ACK> for the last in-sequence segment.  A TCP MUST NOT
    abort a TCP connection if a non-<RST> segment is received without a
    TSopt.

This wording leaves a few ambiguities:

- The first MUST implies some sort of uniform non-RST non-TSopt 
processing, but the rest of the paragraph doesn't provide it.

- The last sentence implies that receipt of a RST non-TSopt could cause 
an abort because of the lack of TSopt; it is because 'abort' is the 
consequence of processed RST.

I suggest clarifying this as:

    Once TSopt has been successfully negotiated (sent and received)
    during the <SYN>, <SYN,ACK> exchange, TSopt MUST be sent in every
    non-<RST> segment for the duration of the connection, and SHOULD be
    sent in a <RST> segment (see Section 4.2 for details).  If a non-
    <RST> segment is received without a TSopt, a TCP MUST drop the
    segment
    and MAY also send an <ACK> for the last in-sequence segment.
    A TCP MUST NOT abort a TCP connection because any segment lacks
    an expected TSopt.

Joe