[openib-general] CM Pathing Question

[Hal Rosenstock]

Hi,

OpenIB is in the midst of implementing the CM and the following question
about the CM has come up on openib-general mailing list and no one has
yet supplied an answer so I thought I'd go to the source. I am cross
posting although members of openib-general won't necessarily be able to
respond directly to any response.

It appears that there is the possibility of a CM path and one or more
data paths (primary/alternate) per connection. The CM path may or may
not be the same as the data path(s).

Assume that a connection with both a primary and secondary path is
setup, using the same primary path for CM communication. Some time later
the primary path fails, so APM causes the connection to migrate to 
the secondary path. A "path migrated" async event is issued in the end
node which results in the desire to set up a new secondary path so that
the connection remains resilent. Where does the LAP get sent ? 
Similarly for any other future CM messages (like DREQ, etc.). It seems
to need to get sent along the new path. 

How is the CM path expected to be maintained in the two cases (when it
is the same and when is different from a data path) in the presence of a
path failure ? Maybe those are the same case in terms of the
architecture.

Thanks for your help with this.

-- Hal