> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Roland Dreier > Sent: Thursday, September 29, 2005 6:50 PM > To: Sean Hefty > Cc: Openib > Subject: Re: [openib-general] [RFC] IB address translation using ARP > > Sean> Can you explain how RDMA works in this case? This is simply > Sean> performing IP routing, and not IB routing, correct? Are you > Sean> referring to a protocol running on top of IP or IB directly? > Sean> Is the router establishing a second reliable connection on > Sean> the backend? Does it simply translate headers as packets > Sean> pass through in this case? > > I think the usage model is the following: you have some magic > device that has an IB port on one side and "something else" > on the other side. Think of something like a gateway that > talks SDP on the IB side and TCP/IP on the other side. > > You configure your IPoIB routing so that this magic device is > the next hop for talking to hosts on the IP network on the other side. > > Now someone tries to make an SDP connection to an IP address > on the other side of the magic device. Routing tables + ARP > give it the GID of the IB port of this magic device. It > connects to the magic device and run SDP to talk to the magic > device, and the magic device magically splices this into a > TCP connection to the real destination. > > Or the same idea for an NFS/RDMA <-> NFS/UDP gateway, etc. >
Those examples are all basically application level gateways. As such they would have no transport or connection setup implications. The application level gateway simply offers a service on network X that it fulfills on network Y. But as far as network X is concerned the gateway IS the server. I do not believe it is possible to construct a transport layer gateway that bridges RDMA between IB and iWARP while appearing to be a normal RDMA endpoint on both networks. Higher level gateways will be possible for many applications, but I don't see how that relates to connection establishment. That would require having an end-to-end reliable connection, complete with flow control semantics, that bridged the two networks by some method other than encapsulation or tunneling. _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
