Re: ISCSI: Urgent Flag requirement violates TCP.

[Matt Wakeley <matt_wakeley@agilent.com>]

Silvano Gai wrote:

> At 04:28 PM 11/7/2000 -0800, Matt Wakeley wrote:
>
> ...
>
> >For example, if the following iSCSI messages are sent:
> >
> >Command A sent to target  ->
> >Command B sent to target  ->
> ><- target sends data/status for command A
> ><- target sends data/status for command B
>
> In the previous example, if Command A and Command B are transmitted in the same segment, do you care to specify if the urgent pointer points to the first or second command?

It would be great if the urgent pointer pointed to the first command.  However (current off the shelf) TCP coalescing will have the urgent pointer point to the second command.

The important thing to remember is that the urgent pointer is only utilized to regain iSCSI PDU framing in the presence of dropped frames.  In reference to your question, it
would be best to regain framing on the first command, but regaining framing on the second command is better than not regaining framing at all.  Also, please remember that due
to the command reference numbering, even though command B was detected (and stored somewhere), it will not be delivered to SCSI until command A is recovered.

-Matt Wakeley
Agilent Technologies

>
>
> -- Silvano
>
> Silvano Gai
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