From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Wise Subject: Re: [PATCH v2] RDMA/CMA: fix iWARP adapter TCP port space usage Date: Wed, 23 Jun 2010 15:29:35 -0500 Message-ID: <4C226EAF.7080805@opengridcomputing.com> References: <4C225078.6050001@opengridcomputing.com> <4C225697.6060702@opengridcomputing.com> <20100623192909.GT4630@obsidianresearch.com> <4C2263B3.9010608@opengridcomputing.com> <20100623195210.GU4630@obsidianresearch.com> <4C226A6F.4000801@opengridcomputing.com> <20100623200937.GV4630@obsidianresearch.com> <4C226C53.7080802@opengridcomputing.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C226C53.7080802-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jason Gunthorpe Cc: Roland Dreier , Bernard Metzler , "Tung, Chien Tin" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Peter P Waskiewicz Jr List-Id: linux-rdma@vger.kernel.org Steve Wise wrote: > Jason Gunthorpe wrote: >> On Wed, Jun 23, 2010 at 03:11:27PM -0500, Steve Wise wrote: >> >>> The IP address assigned for the cxgb3i iscsi device is _not_ >>> assigned to a netdev interface via ifconfig, as far as I understand >>> it (by looking at the cxgb3i code). So the host stack doesn't know >>> about this address. There is an administrative requirement, I >>> assume, that the secret iscsi ipaddr is within a subnet that is >>> bound to the T3 ethX interface. Otherwise the routing lookup >>> wouldn't work. >>> >> >> So who responds to neighbor queries, and how do outgoing queries get >> sent with the right IP? Sounds odd... >> >> > > The iscsi hba is only an initiator, so it doesn't need to respond to > arp queries. I guess the Source Protocol Address in the outgoing ARP > request will be the ipaddr of the outgoing interface. Its ok though > because what is needed is the next-hop peer's hwaddr. So the ARP > reply comes in, updates the host neigh entry, and a NEIGH_EVENT > callout is performed to the offload device drivers. It is a little > hackish, but that's the only way the netdev maintainers would allow > iscsi offload in. They originally tried to use the src address from > the ethX interface for the offload iscsi connections and that was > rejected. > > In case you're interested...Here is the tail end of the cxgb3i original submission thread showing the use of a "private IP address which is unkown to the OS". http://marc.info/?l=linux-netdev&m=121944339211552 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html