Subject: [BEHAVE] PMTUD, TCP MSS, stateless and stateful translation

From: marcelo bagnulo braun <[email-masked]>
Date: Wed, 28 Oct 2009 10:24:46 +0100

Hi,

After looking into the issue regarding PMUTD, i cannot find anything 
that is specific to the stateful translation about PMTUD. Does anybody 
sees anything that should be covered in the statefull document about the 
PMTUD handling? If not, i will refer as much as possible to the 
stateless document for this.

Similar to the TCP MSS handling. I don't think there is anything 
specific about how to handle that to the stateful translator. I will 
also refer then to the stateless translator.

Comments?

regards, marcelo

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From: Iljitsch van Beijnum <[email-masked]>
Date: Wed, 28 Oct 2009 12:11:09 +0100

On 28 okt 2009, at 10:24, marcelo bagnulo braun wrote:

> that is specific to the stateful translation about PMTUD. Does  
> anybody sees anything that should be covered in the statefull  
> document about the PMTUD handling? If not, i will refer as much as  
> possible to the stateless document for this.

Sorry I didn't mention this earlier: but the ID field handling needs  
to be different in a few places.

> also refer then to the stateless translator.

My conclusion a while back was that the added benefit of making  
changes to the TCP MSS option aren't worth the additional complexity.  
In the common situation where all hosts use a 1500-byte MTU there is  
no benefit to modifying the MSS. In some other situations modifying  
the MTU reduces a PMTUD step, but PMTUD needs to work anyway to  
support the cases where the smallest MTU isn't in the first or last hop.

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From: Zhen Cao <[email-masked]>
Date: Wed, 28 Oct 2009 21:34:12 +0800

On Wed, Oct 28, 2009 at 5:24 PM, marcelo bagnulo braun
<[email-masked]> wrote:
> Hi,
>
> After looking into the issue regarding PMUTD, i cannot find anything that is
> specific to the stateful translation about PMTUD. Does anybody sees anything
> that should be covered in the statefull document about the PMTUD handling?
> If not, i will refer as much as possible to the stateless document for this.

Do you mean to remove the text on PMTUD in the xlate-stateful draft
and simply refer to the xlate draft? I am afraid there is no PMTUD
handling in the xlate draft (regarding the ICMP error translation).

And for PMTUD, the translator should keep state according to different
destination addresses. I think it is a stateful behavior.

>
> Similar to the TCP MSS handling. I don't think there is anything specific
> about how to handle that to the stateful translator. I will also refer then
> to the stateless translator

Again, i do not see any detailed text in the stateless draft on TCP
MSS. And, xlate draft would like to cover both stateless and stateful
cases.

>
> regards, marcelo
>
>
>
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> Behave mailing list
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> https://www.ietf.org/mailman/listinfo/behave
>

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From: marcelo bagnulo braun <[email-masked]>
Date: Wed, 28 Oct 2009 16:46:03 +0100

> handling in the xlate draft (regarding the ICMP error translation).

i am in processing of checking the stateless document, so i cannot 
comment just yet, but, if we agree that is common, then it should be in 
the stateless draft imho
> destination addresses. I think it is a stateful behavior.

mmm, you mean that we should store the MTU for each destination we are 
sending packets to, right? But we need that as well in the stateless 
case, right? (i mean  agree that this is state, but i think it is state 
that the stateless translator needs as well, i am afraid. and 
conversely, if the stateless trnaslator does not need it, i guess the 
statefull doesnt need it neither)
> MSS. And, xlate draft would like to cover both stateless and stateful

maybe so, so the point is that we may need to add that?

Regards, marcelo