[openib-general] Problem is routing CM REQ

[Hal Rosenstock]

On Thu, 2007-02-08 at 18:43, Sean Hefty wrote:
> > Looking at the problem more, I think that the issue extends to the remote port 
> > LID as well.  My expectation with a local path record query is that the SLID is 
> > the local port, and the DLID is the local router.  This should be sufficient for 
> > one-way UD traffic, but for connected traffic we still need to discover the 
> > remote router and remote port LIDs.
> 
> Given a path record query for:
> 
> SGID - local
> DGID - remote
> 
> What would be the SLID and DLID?

SLID corresponding to SGID and a DLID for some IB router on the subnet
which can route to the remote DGID.

> And if the query is reversed, such that:
> 
> SGID - remote
> DGID - local
> 
> Are the SLID/DLID values simply reversed?

An SM is free to choose SLID and DLID to supply to if there are multiple
LIDs for the ports in question it can choose alternates. The key here is
whether a reversible path has been requested or not. It is also not
clear what reversible means in the context of an IB internetwork
(multiple IB subnets interconnected by IB routers).

> What if the DGID in the second case were a multicast GID?

So you are asking about what an SA PR lookup for a remote SGID to a DGID
which is an MGID would yield ? I think this too is beyond the spec.

> What does the SLID become in this case?

The SLID couldn't be valid (on a remote subnet) so I'm not sure what
would be said for this case.

-- Hal

> - Sean