From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roland Dreier Subject: Re: [RFC][PATCH 1/1] cxgb3i: cxgb3 iSCSI initiator Date: Wed, 30 Jul 2008 14:35:51 -0700 Message-ID: References: <200807300019.m6U0JkdY012558@localhost.localdomain> <4890C287.60508@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Karen Xie , netdev@vger.kernel.org, open-iscsi@googlegroups.com, davem@davemloft.net, michaelc@cs.wisc.edu, swise@opengridcomputing.com, daisyc@us.ibm.com, wenxiong@us.ibm.com, bhua@us.ibm.com, divy@chelsio.com, dm@chelsio.com, leedom@chelsio.com, linux-scsi , LKML To: Jeff Garzik Return-path: Received: from sj-iport-6.cisco.com ([171.71.176.117]:24249 "EHLO sj-iport-6.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755384AbYG3Vf7 (ORCPT ); Wed, 30 Jul 2008 17:35:59 -0400 In-Reply-To: <4890C287.60508@pobox.com> (Jeff Garzik's message of "Wed, 30 Jul 2008 15:35:35 -0400") Sender: netdev-owner@vger.kernel.org List-ID: > * From a networking standpoint, our main concern becomes how this > interacts with the networking stack. In particular, I'm concerned > based on reading the source that this driver uses "TCP port stealing" > rather than using a totally separate MAC address (and IP). > > Stealing a TCP port on an IP/interface already assigned is a common > solution in this space, but also a flawed one. Precisely because the > kernel and applications are unaware of this "special, magic TCP port" > you open the potential for application problems that are very > difficult for an admin to diagnose based on observed behavior. That's true, but using a separate MAC and IP opens up a bunch of other operational problems. I don't think the right answer for iSCSI offload is clear yet. - R.