<html>
<body>
<font size=3>At 10:30 AM 6/24/2005, Roland Dreier wrote:<br>
<blockquote type=cite class=cite cite=""> Thomas> As
I said - I am not attached to ATS. I would welcome an<br>
Thomas> alternative.<br><br>
Sure, understood. I'm suggesting a slight tweak to the IB wire<br>
protocol. I don't think there's a difference in the security<br>
provided, and carrying the peer address in the CM private data
avoids<br>
a lot of the conceptual and implementation difficulties of ATS.<br><br>
Thomas> But in the absence of one, I like what we
have. Also, I do<br>
Thomas> not want to saddle the NFS/RDMA transport
with carrying an<br>
Thomas> IP address purely for the benefit of a
missing transport<br>
Thomas> facility. After all NFS/RDMA works on iWARP
too.<br><br>
I'm not sure I understand this objection. We wouldn't be saddling
the<br>
transport with anything -- simply specifying in the binding of<br>
NFS/RDMA to IB that certain information is carried in the private
data<br>
fields of the CM messages used to establish a connection.
Clearly<br>
iWARP would use its own mechanism for providing the peer
address.<br><br>
This would be exactly analogous to the situation for SDP --
obviously<br>
SDP running on iWARP does not use the IB CM to exchange IP address<br>
information in the same way the SDP over IB does.</blockquote><br>
Actually, SDP on iWARP uses the SDP port mapper protocol to comprehend
the IP address / port tuples used on both sides of the communication
before the connection is established (this protocol could be used by any
mapping service since it is implemented on top of UDP so could be re-used
by other subsystems like NFS. The TCP transport then connects
normally and one can ask it for the IP address / port tuple that is
really being used. Port mapper may be viewed as akin to the
SID protocol defined for IB. The SDP hello is then exchange in byte
stream as opposed to IB CM. <br><br>
The port mapper supports both centrally managed and distributed usage
models, supports the ability to return diff IP address than requested,
support multiple IP addresses per port, etc. One can construct a
very flexible infrastructure that supports nearly any type of mapping one
desires to same or different hardware or endnodes. It is fairly
light weight and can support caching of data for a period of time or even
a one-shot connection attempt.<br><br>
Mike </font></body>
</html>