Re: ISCSI: Urgent Flag requirement violates TCP.

[Glen Turner <glen.turner@aarnet.edu.au>]

Matt Wakeley wrote:

> > But that's an argument for iSCSI *not* using TCP services beyond the
> > socket API.  To use such services the general purpose
> > computer running TCP/IP offload would then need to change the
> > code in the operating system *and* the code in the ethernet adapter.
> 
> Yeah, what's wrong with that? It sounds to me like you're saying "we
> can't make advances in speed and technology because we have to
> change the OS".

I am saying that the WG needs to be more upfront about its proposal
to alter TCP.

To "make an advance in speed and technology" by altering the services
offered by TCP, a draft that updates RFC793 should be issued.  The
services are listed at the start of RFC793, before the description
of the protocol that implements them.

If the draft becomes a standards-track RFC then operating system
authors can update their TCP implementations to provide the
new service.

The current iSCSI proposal requires the use of a non-existent TCP
service -- that is, the delivery to the application of indexed
octets and the delivery of indexed urgent data.  RFC793 is plain
that the current service is not indexed, but is a stream of octets.

Commercially, my belief is that if iSCSI uses a new TCP service
then the protocol is constrained to being a cheaper alternative
to Fiber Channel for enterprise storage.  Whereas the use of
existing TCP/IP services allows iSCSI to be used to implement
"global storage" (to create some market-speak).

As you may have gathered, it is the global storage potential
of iSCSI that has attracted me to this WG.  Enterprises
sharing high-value storage assets, ISPs offering file-system
independent backup facilities, etc.

Best wishes,
Glen

-- 
 Glen Turner                                 Network Engineer
 (08) 8303 3936      Australian Academic and Research Network
 glen.turner@aarnet.edu.au          http://www.aarnet.edu.au/
--
 The revolution will not be televised, it will be digitised