Subject: Re: [Ips] Login Phase in iSER over IB

From: "Alex Nezhinsky" <[email-masked]>
Date: Wed, 24 Aug 2005 14:00:13 +0300

Mallikarjun C. wrote:
> I do not however think that iSER draft should explicitly sanction a
new iSCSI/MDT
> login mechanism now unless it can reference at least one standard that
defines such 
> a login mechanism. My concern with such a reference would be the
normative 
> dependency and the potential delay.

Mallikarjun,

The only explicit sanctioning here is the requirement to use the same
connection on the 
transport level both for the login and the full-featured phases: 
> The same connection MUST be used for both the iSCSI Login phase and
the subsequent
> iSER-supported Full-Feature phase

This may be achieved in many ways, and the only thing which was intended
to be avoided was  
opening one stream-based connection (like IPoIB) for the Login phase and
then going on with 
a (different) MDT-based connection (like IB RC) for the Full-Feature
phase. 
Such option was proposed by many readers or potential implementers (the
last post 
with such proposal that I read has been issued today) as an intuitive
reaction to the lack of 
stream support in IB RC. 

I believe that you do not have to reference a standard that explicitely
defines a new login 
mechanism, only warn that any such mechanism has to use a single
transport connection.

Alexander Nezhinsky

Software Engineer
Infiniband Storage Solutions
http://www.voltaire.com/
9 Ha-Menofim, Herzelya 46725 Israel
tel: +972- 9- 9717637
fax: +972- 9- 9717660
mobile: +972-50-7504376

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---

From: "Mallikarjun C." <[email-masked]>
Date: Wed, 24 Aug 2005 17:42:53 -0700

Alex,

 > transport level both for the login and the full-featured phases:

I am fine with that requirement.  This is strongly implied in RFC 3720 
and the current iSER draft, and does not create any new dependencies by 
itself.

My concern was about mandating the second statement: "....For a 
transport layer that provides message delivery capability, such as [IB], 
the iSCSI Layer MUST interact with the transport layer directly".  I 
strongly recommend that this statement be deferred to IBTA's iSER/IB RC 
document that presumably complements the IETF iSER draft, rather than 
include it in the iSER draft.

IMO, there is no technical reason to include the 2nd statement in iSER 
draft now at the risk of getting tangled up in the dependency chains on 
the IBTA draft.  iSER draft was deemed indirectly normatively dependent 
on MPA sometime ago because RFC 3720 only defines iSCSI/TCP and MPA is 
thus indirectly required for iSER.  I do not now want the iSER draft to 
enter into an indirect dependency chain on the IBTA draft by mandating 
something that RFC 3720 does not define today.

 From a spec perspective, the "must use same connection for login and 
FFP" language in iSER draft (which I agree with) gives the IBTA document 
authors requisite authority to mandate the other part.

Thanks.

Mallikarjun

Mallikarjun Chadalapaka
Networked Storage Architecture
StorageWorks Division
Hewlett-Packard MS 5668
Roseville CA 95747
cbm [at] rose.hp.com