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

From: [email-masked]
Date: Wed, 6 Nov 2002 12:48:20 -0700

Caitlin,

I don't see anything in the draft that indicates that it is a delta from MPA or that it includes any of the material in MPA. 

Furthermore, MPA has two options for reaction to a CRC error: 
a) if it is tightly coupled to a TCP implementation, TCP can cause the PDU to be resent by not advancing the right edge of the window, or 
b) if built on an existing TCP tell DDP to terminate the connection due to error. 
It isn't clear that the author intended option a to be available for IFT. 

Pat

-----Original Message-----
From: Caitlin Bestler [mailto:[email-masked]]
Sent: Monday, November 04, 2002 5:48 PM
To: [email-masked]
Cc: [email-masked]; [email-masked]; [email-masked]
Subject: Re: [rddp] RE: [Tsvwg] RE:I-D
ACTION:draft-williams-iwarp-ift-00.txt

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.
>
>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.
>

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/
_______________________________________________
rddp mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/rddp