Re: [tcpm] WGLC: draft-ietf-tcpm-urgent-data-02.txt

[Andrew Yourtchenko <[e-mail]>]

Hi Anantha,

On Wed, 10 Feb 2010, Anantha Ramaiah (ananth) wrote:

>
> I had reviewed this document in the earlier versions, just a read again
> caught this and I am seeking clarification :
>
> =============
> 5.  Advice to new applications employing TCP
>
>   As a result of the issues discussed in Section 3.4, new applications
>   SHOULD NOT employ the TCP urgent mechanism.  However, TCP
>   implementations MUST still include support for the urgent mechanism
>   such that existing applications can still use it.
> ================
>
> Why should we be even making this assertion : "new applications SHOULD
> NOT" employ urgent mechanism due to what is said in sec 3.4. The
> end-to-end semantics may get broken/altered due to many reasons and not
> just due to the middlebox fiddling with the URG flag/ptr. I guess my
> point is that why this document take pains in recommending something as
> a result of a middlebox behaviour. The best I have seen so far in
> documents with similar situation is to just mention that middlebox
> behaviour and leave it, do not make any recos based on the middlebox
> behaviour.

We should correct the "3.4" to "3" - i.e. not just middleboxes, but any 
stack that receives the TCP segment with URG flag, will not reliably know 
how exactly to treat it out of three possible interpretations - so any 
application that utilises this mechanism will be inherently very fragile. 
(An example is ABOR with FTP, which does not work correctly most of the 
time).

thanks,
andrew

>
> Makes sense?
>
> -Anantha
>
> PS:- I think this document is ready for LC and the above comment should
> not be construed in any way as to obstructing the document to its
> advancement to LC status.
>
>
>
>
>
>> -----Original Message-----
>> From: [e-mail] [mailto:[e-mail]] On
>> Behalf Of Eddy, Wesley M. (GRC-MS00)[ASRC AEROSPACE CORP]
>> Sent: Wednesday, February 10, 2010 10:43 AM
>> To: David Borman; Fernando Gont; Andrew Yourtchenko (ayourtch)
>> Cc: [e-mail]
>> Subject: Re: [tcpm] WGLC: draft-ietf-tcpm-urgent-data-02.txt
>>
>> I concur with Michael's suggested edits, plus here are some
>> more comments.  Overall, I think it's in good shape and just
>> about ready to publish.  A minor update should be all that's
>> needed, but I do want to make sure that one of the
>> recommendations is worded correctly (see final comment below).
>>
>> Editorial:
>>
>> - section 1, paragraph 3:
>>   "IT accommodates" -> "it accommodates" ?
>>
>> - section 1, paragraph 3:
>>   "using urgent the urgent" -> "using the urgent"
>>
>> - section 1, paragraph 4:
>>   "how current TCP implementations" ->
>>   "how some current TCP implementations"
>>
>>
>> - section 3.2, paragraph 1:
>>   "never reflected into" -> "never was reflected in"
>>
>>
>> Semi-Technical:
>>
>> - section 2.3 - on the allowed length of urgent data, should this
>>   mention that obviously there is a limitation due to the length
>>   of a sequence number field?  You can't send a terabyte of urgent
>>   data.
>>
>> - section 6:
>>   I think it's not worded correctly when we say that applications
>>   using the sockets API MUST set SO_OOBINLINE.  What we really
>>   want to say is more like:
>>
>>   "Even though applications SHOULD NOT employ the urgent mechanism,
>>    applications that require the use of urgent data MUST set
>>    SO_OOBINLINE."
>>
>>   Right?  Apps that don't use urgent data shouldn't have to be
>>   bothered by the fact that it's broken.
>>
>> --
>> Wes Eddy
>> MTI Systems
>>
>>
>>> -----Original Message-----
>>> From: [e-mail] [mailto:[e-mail]]
>> On Behalf Of
>>> David Borman
>>> Sent: Friday, February 05, 2010 2:38 PM
>>> To: [e-mail] WG
>>> Cc: [e-mail]; [e-mail]; Fernando Gont
>>> Subject: [tcpm] WGLC: draft-ietf-tcpm-urgent-data-02.txt
>>>
>>> Note: As recent discussions on this list have indicated, we need
>>> members of this mailing list to be involved.  Please take
>> the time to
>>> read through this document and send a message to the mailing list
>>> either supporting publishing this document, or commenting on
>> why it is
>>> not ready to be published.  This particular document is
>> quite short and
>>> easy to understand.  -David Borman, TCPM co-chair.
>>> ----------------------------
>>>
>>> This is to announce the start of the WG Last Call for:
>>>
>>> Title           : On the implementation of the TCP urgent mechanism
>>> Author(s)       : F. Gont and A. Yourtchenko
>>> Filename        : draft-ietf-tcpm-urgent-data-02.txt
>>> Pages           : 13
>>> Date            : November 26, 2009
>>> Intended Status : Proposed Standard
>>>
>>> http://www.ietf.org/internet-drafts/draft-ietf-tcpm-urgent-da
>> ta-02.txt
>>>
>>> It is our understanding that all the feedback has been incorporated
>>> into this latest version and that there are no known
>> outstanding issues
>>> with this document.
>>>
>>> Please send feedback to the list.
>>>
>>> The WGLC will end on Friday, February 19, 2010.
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