Ethereal-dev: Re: [Ethereal-dev] iSCSI dissector and packets with only data ...

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From: Bill Studenmund <wrstuden@xxxxxxxxxxxxxxxxx>
Date: Mon, 3 Jun 2002 14:03:19 -0700 (PDT)
On Mon, 3 Jun 2002, Guy Harris wrote:

> On Mon, Jun 03, 2002 at 01:46:02PM -0700, Bill Studenmund wrote:
> > Another one would be that if there was a preceeding PDU whose TCP write
> > didn't contain all of the data, then chances are this packet is just data.
>
> Is that "PDU" in the iSCSI sense, or "PDU" in the sense of a TCP
> segment?

PDU in the iscsi sense.

> (I.e., is this an issue that doing TCP reassembly for iSCSI - which is
> supported - would handle, or is there another issue at the iSCSI
> protocol layer?)

I'm not sure, as I'm not familiar with the reassembly for iSCSI.

Since I'm not sure, I'll describe the problem I saw and let you tell me if
it's another issue or not. This problem was seen with 0.9.2; I haven't had
a chance to test with 0.9.4 yet.

The test case was I was watching a test program send NOPs to the target,
and the target was echoing the data back. For reasons I don't understand,
I was seeing:

...

T -> I	4k of data (response)
I -> T  NOP-out + 4 k of data
T -> I  NOP-in pdu

... delay ...

T -> I  4k of data (response)
I -> T  NOP-out + 4 k of data
T -> I  NOP-in pdu

... repeat ...

What I would have liked to see was the 4k of data to show up in the NOP-in
pdu description. Was there a setting I should have turned on to get that?

Take care,

Bill