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

[Joe Touch <[e-mail]>]

FWIW, I was not opening any new issues; I was clarifying the text only. 
I don't believe my new text changes any of the meaning from the previous 
intended version; IMO it only better handles ambiguities.

We discussed the reason for these requirements before.

Joe

On 5/24/2013 12:57 AM, Olivier Bonaventure wrote:
> Joe, Yuchung,
>
>> 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).
>
> I fail to see the rationale for forcing a TCP connection to always send
> the TSopt in every segment. The timestamp aids to estimate the rtt and
> provides PAWS for long connections. Given the size of the TCP option
> space, we should not force the utilisation of the TSopt in all segments.
> Consider a TCP implementation that supports SACK, RFC1323 and TCP-AO or
> Multipath TCP. When this implementation sends an ACK segment that
> contains a SACK, is it better to encode a long SACK block or to use
> option space to encode a timestamp ? I'd vote for providing a timestamp
> from time to time and reporting accurate SACK blocks.
>
>
>  > 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.
>
> Dropping segments that do not contain the TSopt is excessive. There are
> on the Internet middleboxes that coalesce or split segments. While doing
> that, they may remove options. Dropping a segment because it does not
> contain the TSopt which is only informative appears overkill to me.
> Dropping a segment that does not contain the negotiated TCP-AO option
> makes sens, but not for the TSopt.
>
>
> Olivier
>
>