Re: [tcpm] Definition of SMSS/RMSS in RFC5681 are inaccurate?!

[Alexander Zimmermann <[e-mail]>]

Hi Joe,

Am 26.07.2010 um 17:58 schrieb Joe Touch:

> Hi, all,
> 
> On 7/26/2010 8:43 AM, Hagen Paul Pfeifer wrote:
>> 
>> On Mon, 26 Jul 2010 14:33:26 +0200, Alexander Zimmermann wrote:
>> 
>>> The size does not include the TCP/IP headers and options. This is wrong!
>>> The options are the TCP/IP headers.
>> 
>> Strange that nobody spotted this. "The options are the TCP/IP headers",
>> what does this mean? draft-ietf-tcpm-tcpmss-03 should be mentioned instead:
>> 
>>    The MSS value to be sent in an MSS option should be equal to the
>>    effective MTU minus the fixed IP and TCP headers.
> 
> Some of us just spotted this, and you just typed faster than we did ;-)
> 
> Yes, RFC5681 is correct,

Sorry, but I disagree. I cite the sentence in question again:

"The size does not include the TCP/IP headers and options."

The "and" in the sentence is IMO wrong or at least very very misleading.
Either we write: "The size does include ONLY the fixed TCP/IP headers."
or we write "The size does not include the TCP/IP options" 


Alex

> and draft-ietf-tcpm-tcpmss intends to update RFC879 and RFC2385.
> 
> Note that RFC2385 is already obsoleted by RFC5925, which states:
> 
>   Please note that the use of TCP-AO does not affect TCP's advertised
>   maximum segment size (MSS), as is the case for all TCP options
>   [Bo09].
> 
> This statement is consistent with draft-ietf-tcpm-tcpmss, FWIW.
> 
> (Dave - does this mean that draft-ietf-tcpm-tcpmssSec 3.2 might include a note that it updates 2385 even though 2385 is obsoleted...?)
> 
> Joe