Subject: RE: iSCSI: NOPs on discovery session

From: "John Hufferd" <[email-masked]>
Date: Thu, 6 Dec 2001 02:19:55 -0800

I do not see any reason to keep the decovery session up.  Why would it be
needed to stay up?

.
.
.
John L. Hufferd
Senior Technical Staff Member (STSM)
IBM/SSG San Jose Ca
Main Office (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
Home Office (408) 997-6136, Cell: (408) 499-9702
Internet address: [email-masked]

"Ayman Ghanem" <[email-masked]>@ece.cmu.edu on 12/05/2001 09:37:34 PM

Sent by:  [email-masked]

To:   <[email-masked]>
cc:
Subject:  RE: iSCSI: NOPs on discovery session

Julian,

I would vote for  allowing it. Is the spec going to require the initiator
to logout immediately  after the SendTargets response is received?. Should
the target drop the session  after it had sent the response?. I am not sure
how the  discovery session could be misused. It has been authenticated like
any other  session and has only limited set of commands. One could also
argue the need for  logout on a discovery session as opposed to just
closing the  connection.

-Ayman

-----Original Message-----
From: [email-masked]  [mailto:[email-masked]]On Behalf Of
Julian  Satran
Sent: Tuesday, December 04, 2001 1:05 AM
To:  [email-masked]
Subject: Re: iSCSI: NOPs on discovery  session

Ayman,

It is true that I agreed that we may want  to have it. However some members
of the list have expressed immediately a  strong opposition to it claiming
that it was no strictly needed (true) and  that discovery section are meant
to be brief.
I felt thus that we don't have a consensus on that and we may want to  try
again.
I assume that the main  concern was that this will enable discovery
sessions to be become long lived  and be used as a back door monitoring
channel.

Regards,
Julo

                             "Ayman Ghanem"                                 
                             <[email-masked]>              To:           
                             Sent by:                 <[email-masked]>     
                             [email-masked]            cc:           
                                                               Subject:     
                             12-04-01 05:30 AM        iSCSI: NOPs on        
                                                      discovery  session    

Julian,

I thought we agreed to adding NOPs to the operations  allowed on the
discovery session. I couldn't find that in draft-09.  Thanks.

-Ayman

---

From: "Ayman Ghanem" <[email-masked]>
Date: Thu, 6 Dec 2001 09:08:03 -0600

If the initiator choose to keep the discovery session up, the target could
use it to inform the initiator of new targets or LUNs it can access.

-Ayman

> John Hufferd
> Sent: Thursday, December 06, 2001 4:20 AM
> To: Ayman Ghanem
> Cc: [email-masked]
>                                                       discovery
> session

---

From: "Mark S. Edwards" <[email-masked]>
Date: Thu, 06 Dec 2001 15:31:19 +0000

>use it to inform the initiator of new targets or LUNs it can access.

SLP and iSNS will already do this and since SLP is mandatory to implement, 
this feature already exists.

Discovery sessions should be short lived, they tie up network 
resources.  Can you imagine 1000 initiators with long lived discovery 
sessions on a target ?  Any sensible target will probably implement a timer 
on a discovery session anyway.

Mark.

---

From: "Ayman Ghanem" <[email-masked]>
Date: Thu, 6 Dec 2001 10:18:26 -0600

That is true. However, this is an implementation issue. My point is there is
nothing in the spec that requires either side to drop the discovery session
after the initial discovery is completed. So, the question is: if this
session can stay active long enough, should this command be disallowed?. The
key "SendTargets" is also mandatory and there is no restriction on when/how
it can be issued.

-Ayman

> Mark S. Edwards
> Sent: Thursday, December 06, 2001 9:31 AM
> To: [email-masked]

---

From: Mark Bakke <[email-masked]>
Date: Thu, 06 Dec 2001 11:21:52 -0600

If a client wants to receive async messages when new iSCSI targets
become available, or wants to poll once in a while with SentTargets,
it is better to keep the discovery session there.  This is useful
in cases where iSCSI gateways are connected through firewalls; only
the iSCSI protocol needs to be allowed through the firewall to do
this type of discovery.

--
Mark

---

From: Mark Bakke <[email-masked]>
Date: Thu, 06 Dec 2001 11:33:21 -0600

Mark-

This is true, but in cases where iSCSI is run through firewalls,
it may be easier to just allow the iSCSI port through the
firewall, and not allow the discovery protocols.  This makes
SendTargets the only way to do discovering in this situation,
and to use an async message for discovery as targets become
available requires the session to be kept around.

Keep in mind that this may not be the normal, everyday way to
use a discovery session, so not all discovery sessions will
have to be long-lived.  I think that this is a necessary option
to provide for the firewall situation.

--
Mark