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 15:11:27 -0500 Message-ID: <4C226A6F.4000801@opengridcomputing.com> References: <4C225078.6050001@opengridcomputing.com> <4C225697.6060702@opengridcomputing.com> <20100623192909.GT4630@obsidianresearch.com> <4C2263B3.9010608@opengridcomputing.com> <20100623195210.GU4630@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20100623195210.GU4630-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@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 Jason Gunthorpe wrote: > On Wed, Jun 23, 2010 at 02:42:43PM -0500, Steve Wise wrote: > >>> I wonder how does neighbor discovery, routing, etc work with iscsi? >>> >> For cxgb3i: >> >> ND is handled by initiating ND via exported kernel services >> (neigh_event_send()) and registering for NETEVENT_NEIGH_UPDATE net >> events to get updated neigh entries. >> >> The host routing table is consulted via ip_route_output_flow() to map a >> destination ip address to a local netdev, and then if that device is T3, >> it will do the iscsi offload. >> > > That is what RDMA does.. So that means that the IP used for iscsi is > actually an IP assigned to the interface? > > 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. Steve. -- 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