Re: iSCSI: Logout for a Session

[Santosh Rao <santoshr@cup.hp.com>]

The use of a Logout to close the connection [and the session if this is
the last connection being closed] is preferred to just closing the TCP
connection since the logout command PDU provides the other end a "Reason
Code" that explains the reason for the close.

2 comments regarding logout :
i) The draft should change :
"An initiator MAY use a logout command to remove a connection from a 
   session."

   to :
"An initiator MUST use a logout command to remove a connection from a 
   session."

This ensures only one way of doing things, communicates a reason code for
the close of connection and does its bit for the cause of successful
interopability.

ii) The reason code :
"2 - Remove the connection at targets requests (requested 
      through an AEN)"

along with the corresponding AEN iSCSI event indicator :
"2    Target requests Logout on this connection "

MUST be removed and targets allowed to originate a logout. This allows
targets the ability to drive the logout and is a useful feature in cases
like targets wishing to commence an online firmware upgrade on one of
their channels. In such situations, it is un-desirable for the targets to
send AENs and then wait [and hope] that the initiator will log the target
out.

For all one knows, several O.S. drivers may decide to ignore AENs !

Targets SHOULD be allowed to originate logouts.

- Santosh



> 
> Isn't a session terminated when the last TCP connection is closed?
> -paul
> 
> Paul Grun                                              
> Intel Corporation
> Enterprise Platform Group
> Fabric Components Division
> (503) 677-6768
> paul.grun@intel.com <mailto:paul.grun@intel.com> 
> 
> 
> > -----Original Message-----
> > From: Matt Wakeley [mailto:matt_wakeley@agilent.com]
> > Sent: Wednesday, January 10, 2001 12:59 PM
> > To: IPS Reflector
> > Subject: iSCSI: Logout for a Session
> > 
> > 
> > Throughout the iSCSI document, it talks about the logout 
> > command closing a TCP
> > connection.  Especially for the purposes of error recover to 
> > terminate a TCP
> > connection and "clean up" so that another TCP connection can 
> > be established to
> > continue the session.  There seems to be no way to indicate 
> > that a session is
> > being terminated.
> > 
> > There should be a flag in the logout command that indicates 
> > that the *session*
> > is being terminated (as well as the TCP connection).
> > 
> > -Matt Wakeley
> > Agilent Technologies
> > 
> 
> 


-- 
#################################
Santosh Rao
Software Design Engineer,
HP, Cupertino.
email : santoshr@cup.hp.com
Phone : 408-447-3751
#################################