[openib-general] [RFC] CM reject handling and redirection

[Roland Dreier]

I think the simplest solution the solution most in keeping with the
design of the CM is to always expose the rejection and the contents of
the REJ to the consumer.  As you say, that makes the code 24 (port &
CM redirection) case pretty easy to handle.

Code 25 (port redirection only) raises a separate issue that I think
is orthogonal to REJ handling.  The CM spec always allows the CM to
run on a different port from the destination of a connection so if we
want to implement the whole spec we do need a way for the consumer to
specify a primary and alternate path for the connection itself as well
as a CM path.

However, I don't know of any real applications that run the CM on a
different port from the port being connected to, so I don't know that
we need to support this (but once we do, REJ code 25 is easy to handle).

As you say, separating the CM path from the connection path does raise
the question of what to do for failover and APM.  As far as I can tell
this is an area that the IB spec is silent on and I'm not sure that
anyone ever came up with a good answer.

 - R.