Subject: RE: [rddp] IPsec & Markers

From: "Culley, Paul" <[email-masked]>
Date: Mon, 11 Oct 2004 08:37:17 -0500

I'm not sure what more you want to do with markers than you can already
do.  It is legal for endpoints to specify "Don't transmit Markers to me"
(See 'M' bit in MPA connection setup).  If your endpoint is certain it
can always decode FPDUs without markers, then set this bit to zero.  The
other end is still free to ask for markers for FPDUs going to it, of
course.

Of course you must still be prepared for potential alignment breaks,
even if you are doing IPSEC, since there is no requirement that senders
always align or pack perfectly into segments.  And you will always have
to process FPDUs in order (to use the length field check) to safely
identify the FPDU boundaries.  Note that the group agreed that CRC
checks were NOT sufficient for FPDU boundary identification.

If you were thinking of adding some kind of requirement that when doing
IPSEC, senders MUST perfectly align and segment one FPDU to TCP segment,
I think that would be a very difficult battle in the IETF.

Paul R. Culley
HP Fellow
281-514-5543

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On 
> Behalf Of Michael C. Cambria
> Sent: Friday, October 08, 2004 9:51 PM
> To: Krause, Michael R
> Cc: [email-masked]
> Subject: Re: [rddp] IPsec & Markers
> 
> 
> 
> Michael Krause wrote:
> 
> > 
> > I hate to bring this up but from a process perspective, did we not 
> > already achieve consensus that markers would always be 
> required?  We 
> > are getting towards last call so it would be good to avoid 
> re-opening 
> > a topic if it has already reached consensus.
> 
> The WG only agreed to make IPsec mandatory to implement in 
> San Diego (2 months ago).  I never suggested anything other 
> than being able to do for markers what one can do for CRC 
> when running over IPsec.
> 
> MikeC
> 
> 
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---

From: "Michael C. Cambria" <[email-masked]>
Date: Mon, 11 Oct 2004 10:55:42 -0400

> I think that would be a very difficult battle in the IETF.

Not must, but MAY (then either communicate this at start or "turn the 
knob" at boot time.

Uncle.   :-)

 > Note that the group agreed that CRC

I never found that in the archives.  I found lots of people suggesting 
this, but not a WG consensus.  I was personally convinced when Caitlin 
Bestler wrote (9 April 2004) "... there is no rule that says a valid DDP 
Segment could not be the *payload* that is being delivered within a DDP 
Segment."

That said, the archives are unreliable.  See the bottom of 
ftp://ftp.ietf.org/ietf-mail-archive/rddp/.

I also got the impression, reading the TSVWG archives, that middleboxes 
(which would be ruled out with IPsec) were the problem not the RNIC 
endpoints.  That was consistent with my personal experience from 
pre-DLSw days through "today" of sending frames in TCP and never having 
one received unaligned when both ends of the connection adhered to the 
"spec".  Hence this thread suggesting "no middlebox, no problem".

Regards,
MikeC

-- 
Michael C. Cambria

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