Re: [ofa-general] [PATCH v3] iw_cxgb3: Support"iwarp-only"interfacesto avoid 4-tuple conflicts.

[Steve Wise <swise@opengridcomputing.com>]

Kanevsky, Arkady wrote:
> Sean,
> IB aside,
> it looks like an ULP which is capable of being both RDMA aware and RDMA
> not-aware,
> like iSER and iSCSI, NFS-RDMA and NFS, SDP and sockets, 
> will be treated as two separete ULPs.
> Each has its own IP address, since there is a different IP address for
> iWARP
> port and "regular" Ethernet port. So it falls on the users of ULPs to
> "handle" it
> via DNS or some other services.
> Is this "acceptable" to users? I doubt it.
>
> Recall that ULPs are going in opposite directions by having a different
> port number for RDMA aware and RDMA unaware versions of the ULP.
> This way, ULP "connection manager" handles RDMA-ness under the covers,
> while users plug an IP address for a server to connect to.
> Thanks,

Arkady, I'm confused about how this proposed design changes the behavior 
of the ULPs that run on TCP and iWARP.  I don't see much difference from 
the point of view of the ULPs.

The NFS-RDMA server, for example, will not need to change since it binds 
to address 0.0.0.0 which will translate into a bind/listen on the 
specific iwarp address for each iwarp device on the rdma side, and 
address 0.0.0.0 for the TCP side.

Am I missing your point?

The real pain, IMO, with this solution is that it FORCES the admins to 
use 2 subnets when 1 is sufficient if the net maintainers would unify 
the port space...

Steve.



> Arkady Kanevsky                       email: arkady@netapp.com
> Network Appliance Inc.               phone: 781-768-5395
> 1601 Trapelo Rd. - Suite 16.        Fax: 781-895-1195
> Waltham, MA 02451                   central phone: 781-768-5300
>  
>
> > -----Original Message-----
> > From: Sean Hefty [mailto:sean.hefty@intel.com] 
> > Sent: Thursday, September 27, 2007 3:12 PM
> > To: Kanevsky, Arkady; Sean Hefty; Steve Wise
> > Cc: netdev@vger.kernel.org; rdreier@cisco.com; 
> > linux-kernel@vger.kernel.org; general@lists.openfabrics.org
> > Subject: RE: [ofa-general] [PATCH v3] iw_cxgb3: 
> > Support"iwarp-only"interfacesto avoid 4-tuple conflicts.
> >
> > > What is the model on how client connects, say for iSCSI, when client 
> > > and server both support, iWARP and 10GbE or 1GbE, and would like to 
> > > setup "most" performant "connection" for ULP?
> > For the "most" performance connection, the ULP would use IB, 
> > and all these problems go away.  :)
> >
> > This proposal is for each iwarp interface to have its own IP 
> > address.  Clients would need an iwarp usable address of the 
> > server and would connect using rdma_connect().  If that call 
> > (or rdma_resolve_addr/route) fails, the client could try 
> > connecting using sockets, aoi, or some other interface.  I 
> > don't see that Steve's proposal changes anything from the 
> > client's perspective.
> >
> > - Sean
> > _______________________________________________
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> > general@lists.openfabrics.org
> > http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general
> >
> > To unsubscribe, please visit 
> > http://openib.org/mailman/listinfo/openib-general
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