[openib-general] Some ib_mad.h Redirection Comments

[Sean Hefty]

On Thu, 05 Aug 2004 09:03:47 -0400
Hal Rosenstock <halr at voltaire.com> wrote:

Obviously, I haven't thought through all of the details on this, so some discussion is good.

> Does ib_mad_qp_redir need to take a ib_mad_reg_req parameter or at least
> a GS class ?

I don't think it's necessary.  The ib_mad_reg_req is used to route unsolicited MADs to the proper client.  Since the user has control over the QP and CQ in the redirected case, they receive all MADs on the QP that they are redirecting to.
 
> How is the redirection information in a GS agent's ClassPortInfo filled
> in ? Is this part of what register and redirection (maybe a different
> one from what is proposed) should handle ? The redirection can occur to
> a remote QP, not just a QP on the local node.

I was assuming that the client would format (maybe with help) and send the redirection message.  Redirection messages, therefore, would flow from client to client.  If a simpler redirection interface were desired, it could be built on top of the proposed APIs, but I think that that could be above the access layer.

> In terms of a GS entity making requests (which have responses), if it is
> redirected, will the retransmission to the redirected location occur
> without consumer intervention ?

I was assuming not.  Since redirection comes as a response to a request, my thought was to complete the request as redirected.  (Maybe we can add another completion status value.)  It should be fairly simple for the client to re-issue the send to the redirected QP.  The benefit of this is that the client can automatically send future requests to the redirected QP.