RE: Performance of iSCSI, FCIP and iFCP

["Douglas Otis" <dotis@sanlight.net>]

Franco,

As a layman, FCP is responsible for ordered delivery but a timestamp would
help both merging multiple streams as well as filtering out stale frames
stalled by intermittent network disruptions.  The layer above IP transport
should allow needed freedom for adding additional paths.

Doug

Could an FCIP expert reply to the technical question that Victor raised in
this message?

thanks
-franco

At 02:47 PM 1/10/01, Firoiu, Victor [BL60:470-M:EXCH] wrote:


Vi,

thanks for your comments.  Indeed, there is no such limitation in the
FCIP ID.  But there is no consideration for multiple TCP connections
either.  What specifically governs the use of TCP flow A as opposed to
TCP flow B when two FCIP gateways are communicating?

As we've seen in our examples, the performance is significantly
(quadratically) impacted by the choice of number of TCP connections.
Fine-grain control over multiple TCP connections thus becomes
mandatory between any two FC islands of non-trivial size.  The most
natural way to multiplex storage connections (FC or SCSI) on multiple
TCP connections is to have one or a few TCP connections per storage
connection, that is, to use storage connection awareness for assigning
TCP connections to storage connections (iSCSI, iFCP).

Surely, it is possible to multiplex storage connections into TCP
connections without any knowledge of the identity of storage
connections.  But this brings up issues including load balancing,
interdependency between storage connections sharing TCP connections,
managing storage connections that are striped across TCP connections
(as thoroughly discussed within the iSCSI community).  It seems that
the iSCSI and iFCP solution of assigning one (or a few) TCP
connection(s) for each storage connections has many practical and
performance merits that needs a special attention in FCIP also.

Again, any comments are very welcome.

Victor Firoiu
-----
Content Internetworking Lab, Technology Center
Nortel Networks, Inc.
600 Technology ParkBillerica, MA 01821 USA

Vi Chau wrote:
>
> Hi,
>
>    There is nothing in the FCIP I-D that limits the
> tunnel between the SAN islands to one TCP connection. The
> FCIP gateways can open as many TCP connections as it can
> support to reach any number of destination gateways.
>
> Vi Chau
> Gadzoox Networks, Inc.
> 16241 Laguna Canyon Road, Suite 100
> Irvine, CA 92618-3611
> 949-789-4639
>