[Rdma-developers] Re: [openib-general] OpenIB and OpenRDMA: Convergence on common RDMA APIs and ULPs for Linux

[Michael Krause]

At 06:40 AM 5/27/2005, Sukanta ganguly wrote:
>Venkata,
>    How will that work? If the RNIC offloads RDMA and
>TCP completely from the Operating System and does not
>share any state information then the application
>running on the host will never be in the position to
>utilize the socket interface to use the communication
>logic to send and receive data between the remote node
>and itself. Some information needs to be shared. How
>much of it and what exactly needs to be shared is the
>question.

Ok.  It all depends upon what level of integration / interaction a TOE and 
thus a RNIC will have with the host network stack.  For example, if a 
customer wants to have TCP and IP stats kept for the off-loaded stack even 
if it is just being using for RDMA, then there needs to be a method defined 
to consolidate these stats back into the host network stack tool 
chain.  Similarly, if one wants to maintain a single routing table to 
manage, etc. on the host, then the RNIC needs to access / update that 
information accordingly.  One can progress through other aspects of 
integration, e.g. connection management, security interactions (e.g. DOS 
protection), and so forth.  What is exposed again depends upon the level of 
integration and how customers want to manage their services.  This problem 
also exists for IB but most people have not thought about this from a 
customer perspective and how to integrate the IB semantics into the way 
customers manage their infrastructures, do billing, etc.  For some 
environments, they simply do not care but if IB is to be used in the 
enterprise space, then some thought will be required here since most IT 
don't see anything as being "free" or self-managed.

Again, Sockets is an application API and not how one communicates to a TOE 
or RDMA component.  The RNIC PI has been proposed as an interface to the 
RDMA functionality.  The PI supports all of the iWARP and IB v 1.2 verbs.

Mike


>Thanks
>SG
>
>--- Venkata Jagana <jagana at us.ibm.com> wrote:
> >
> >
> >
> >
> >
> >
> > rdma-developers-admin at lists.sourceforge.net wrote on
> > 05/25/2005 09:47:00
> > PM:
> >
> > > Venkata,
> > > Interesting coincidence: I was talking with
> > someone (at HP) today
> > > who knows substantially more than I do about
> > RNICs.
> > > They indicated RNICs need to manage TCP state on
> > the card from userspace.
> > > I suspect that's only possible through a private
> > interface
> > > (e.g. ioctl() or /proc) or the non-existant (in
> > kernel.org)
> > > TOE implementation. Is this correct?
> > >
> >
> > Not correct.
> >
> > Since RNICs are offloaded adapters with RDMA
> > protocols layered on
> > top of TCP stack, they do maintain the TCP state
> > internally but
> > it does not expose to the host. RNIC expose only
> > RNIC Verbs interface
> > to the host bot not TOE interface.
> >
> > Thanks
> > Venkat
> >
> > >
> > > hth,
> > > grant
> > >
> > >
> > >
> >
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