RE: FC/IP vs. iSCSI

["Rodriguez, Elizabeth G (Elizabeth)" <egrodriguez@lucent.com>]

All,

The purpose of FC over IP is to extend FC networks with minimal impact to
existing devices and existing installations.
It is not intended to be an iSCSI equivalent/counterpart, e.g. I would not
expect someone to put FC over IP into an end device.  It is really intended
to be something put into a switch, not at an endpoint.

If you have an existing FC environment, the question is not whether you
could run GigE as well (you could, and probably would), but do you want to
replace all the existing FC environment (e.g. all the existing FC
controllers, disks, tapes, RAID, JBOD, etc), with new equipment, (equipment
that is iSCSI compliant), or do you want to add a single device at the edge
of each of your FC fabrics, and enable the fabrics to overcome distance
limitations utilizing a network that is already in place for other LAN/WAN
traffic.

Over the next few days, I will post more information about FC over IP to
this reflector.
This will include some of the items that will most likely become
requirements for the FC over IP draft.
Included will be some requirements addressing Costa's comments below.

Elizabeth Rodriguez
Lucent Technologies
-----Original Message-----
From: Matthew Jacob [mailto:mjacob@feral.com]
Sent: Wednesday, August 16, 2000 6:16 PM
To: csapuntz@cisco.com
Cc: ips@ece.cmu.edu
Subject: Re: FC/IP vs. iSCSI



I'm certainly inclined to agree. The sole realistic purpose of requirements
I've seen to date FC/IP is to utilize an existing FC environment so that
management and data go over the same wire. If you're carrying SCSI over
TCP/IP
now, it's somewhat absured to try and carry FC/IP over the same transport.
It's as if you want to tunnel TCP/IP over TCP/IP, which is a cute trick, but
a
trick for all that.

If you have an existing FC optical environment, it could probably run
GigEthernet just as well- and it then becomes a question as to whether iSCSI
serves the systems and applications as well or better than FC-SCSI or FC/IP
over the same physical media.

-matt


On 16 Aug 2000 csapuntz@cisco.com wrote:

> 
> FC/IP is NOT an alternative to iSCSI for most applications.
> 
> Unfortunately, making a protocol that works well in complex networks
> is not as simple as just putting stuff into IP packets. IP packet
> headers are not magical pixie dust that suddenly make higher-layer
> protocol issues go away.
> 
> The FibreChannel stack today has the following deficiencies which do
> not disappear when tunneling over IP:
> 	- FCP has no congestion control
> 	- FCP deals poorly with packet loss
> 	- Target naming is done with either 24-bit port IDs or 64-bit WWNs,
> 	   neither of which scale to Internet size
> 	- No secure login
> 
> Of course, you could address all the deficiencies by fixing FCP. But
> by the time you do that, I maintain you will most likely end up with
> something in the same order of complexity as iSCSI/TCP/IP.
> 
> -Costa
> 
>