At 06:40 AM 5/27/2005, Sukanta ganguly wrote:
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Michael Krause
Sent: Friday, May 27, 2005 7:25 AM
To: Sukanta ganguly
Cc: openib-general@openib.org; [EMAIL PROTECTED]
Subject: Re: [Rdma-developers] Re: [openib-general] OpenIB and OpenRDMA: Convergence on common RDMA APIs and ULPs for Linux
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
I'd like to add that RNIC-PI is
planning on explicitly defining some of these "obvious"
dependencies
between the RDMA stack and the
primary IP stack. For example, the RDMA stack cannot maintain
any connection in a state that
contradicts current IP stack routing. It has to adapt or break the
connection.
We can't have an RNIC that has its
own ARP table that is not in sync with the host's ARP table.
An iWarp RDMA stack gains the benefit of many pre-existing network
services (such as DNS, ARP
and routing). But that also carries with it the need to not contradict
those exisiting services. So it is
both a benefit and a restriction -- and a major divergence from an IB
RDMA stack.
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