Subject: [rddp] RE: [Tsvwg] RE:I-D ACTION:draft-williams-iwarp-ift-00.txt

From: [email-masked]
Date: Mon, 4 Nov 2002 18:05:53 -0700

Jim,

The draft specifies a frame format but does not have the necessary information to make this protocol a functional interface between DDP and TCP. 

In particular, the draft does not specify the action the protocol is required to take when it receives a frame with a CRC error. 

IFT cannot just silently drop the packet. DDP and RDMAP protocols have been simplified by requiring that the underlying transport to provide a reliable data stream. They have no mechanisms to detect dropped packets or to cause such packets to be resent.

How does IFT recover the lost packet?

Assuming it was the header CRC that failed, how does it regain sync to frame boundaries?

At this point, it is not a complete proposal.

Regards,
Paat
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---

From: Caitlin Bestler <[email-masked]>
Date: Mon, 4 Nov 2002 19:48:03 -0600

On 11/4/02, [email-masked] wrote:

>Jim,
>
>The draft specifies a frame format but does not have the
>necessary information to make this protocol a functional
>interface between DDP and TCP. 
>
>In particular, the draft does not specify the action the
>protocol is required to take when it receives a frame with
>a CRC error. 
>
>IFT cannot just silently drop the packet. DDP and RDMAP
>protocols have been simplified by requiring that the
>underlying transport to provide a reliable data stream.
>They have no mechanisms to detect dropped packets or to
>cause such packets to be resent.
>

IFT is currently presented as a delta from MPA, which is
probably incorrect. It certainly would need to be fixed if
IFT were drafted over MPA, since MPA would cease to exist.

But aside from formalities, my assumption has been that Jim
was not proposing any other changes. Hence the local
interface and error semantics in the MPA document would be
merged into a completed document.

The two main points of IFT versus MPA are the elimination of
markers and splitting off of the header checksum. I'm not
convinced of the merit of either change, but they are both
worthy of more detailed discussion in this public forum.

Caitlin Bestler
http://asomi.com/CaitlinBestler/
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