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<p><tt>rdma-developers-admin@lists.sourceforge.net wrote on 05/27/2005 10:40:20 AM:<br>
<br>
<br>
> > On Fri, May 27, 2005 at 09:58:44AM -0700, Caitlin Bestler wrote:<br>
> > > > I understand most of what you wrote but am still missing one bit:<br>
> > > > How is the RNIC told what the peer IP is it should <br>
> > communicate with?<br>
> > > <br>
> > > The TCP Connection is already established before the RNIC takes <br>
> > > control of the connection. Therefore the entire TCP state <br>
> > is already <br>
> > > established (source/dest IP Address/Port, negotiated options, EMSS, <br>
> > > local options, etc.).<br>
> > <br>
> > Would "shares the connection" be a better description?<br>
> > <br>
> <br>
> No, it does not "share the connection". After conversion the <br>
> RDMA stack is in full control of the TCP layer. The host cannot<br>
> modify anything about the TCP layer, or use its services.<br>
> For example the host cannot enable Nagle on the TCP connection<br>
> after it has been turned over to the RNIC. It definetly cannot<br>
> send or receive streaming data. Because of the nature of the<br>
> MPA protocol, a TCP connection that has been enabled for MPA<br>
> can *never* revert to non-MPA mode. It can only be used in MPA<br>
> mode or terminated.<br>
> </tt><br>
<br>
<tt>Agree that it is never being shared but once the connection has been</tt><br>
<tt>turned over to the RNIC, would it ever be possible to hand it back</tt><br>
<tt>to the host or host taking control from the RNIC adapter? Might be </tt><br>
<tt>helpful for failover situations.</tt><br>
<br>
<tt>Thanks</tt><br>
<tt>Venkat<br>
</tt><br>
<tt>> It's the L2 and L3 layer data that is shared (or synchronized)<br>
> between the host and the RNIC.<br>
> <br>
> > I think I get the concepts at least now...this follows what I <br>
> > was suggesting earlier about having an RNIC support both NAPI <br>
> > (New API for NICs) (code under drivers/net) and openib.org <br>
> > Gen2 stack (code in drivers/infiniband).<br>
> > <br>
> > thanks,<br>
> > grant<br>
> > <br>
> <br>
> <br>
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