Subject: Re: iSCSI : LUN field in NOP-OUT & NOP-IN PDUs.

From: [email-masked]
Date: Thu, 26 Apr 2001 09:52:18 +0300

Santosh,

In NOPs the LUNs are used only if the exchange is originated by the target
and then the LUN is
has to be valid.

Otherwise the LUN is 0 (when the target task tag is ffffffff).

I've added to the NOP-out figure the "or Reserved (0)".

In rest the text explaines exactly what I said here.

Julo

Santosh Rao <[email-masked]> on 23/04/2001 22:14:54

Please respond to Santosh Rao <[email-masked]>

To:   IPS Reflector <[email-masked]>
cc:
Subject:  iSCSI : LUN field in NOP-OUT & NOP-IN PDUs.

At the risk of raising a subject that has been beaten to death [and
still not resolved ?], could someone please clarify on what was the
outcome of the prior thread discussing the usage of the LUN field in
NOP-OUT & NOP-IN PDUs ?

As has been discussed in the past, the NOP-OUT and NOP-IN PDUs are
transport specific and are used without any LUN context. Hence, it is
not clear why a LUN field is required in either the NOP-OUT or NOP-IN
PDUs.

Some side notes on this subject :
a) the LUN field description is missing in the NOP-OUT description and
it is not clear from either the figure or the text whether this field
can be reserved. If so, what would be the reserved value for LUN in
NOP-OUT ?

b) The NOP-IN PDU description shows a value of LUN 0 as reserved in the
NOP-IN PDU diagram. Is not LUN 0 a valid LU number for a LU (?)

- Santosh
 - santoshr.vcf

---

From: Santosh Rao <[email-masked]>
Date: Thu, 26 Apr 2001 11:47:11 -0700

> Otherwise the LUN is 0 (when the target task tag is ffffffff).

Julian,

If the target originates a NOP-IN, are you saying that the LUN field
must be valid and contain a non-zero LUN value ? FYI, LUN 0 is a valid
LUN. Why cannot the target use LUN 0 in this case ?

Also, what if the target is assigning target transfer tags on a per
session basis. What should such a target initialize the LUN field to ? 

IMO, the NOP-OUT and NOP-IN PDUs should allow a LUN field and let it be
set to LUN 0 if the targets are assigning tags on a per session basis.
(LUN 0 implying target SDP).

- Santosh