[openib-general] Problem is routing CM REQ

[Hal Rosenstock]

On Fri, 2007-02-09 at 12:22, Sean Hefty wrote:
> > SLID corresponding to SGID and a DLID for some IB router on the subnet
> > which can route to the remote DGID.
> 
> This was my assumption as well.
> 
> > 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).
> 
> For simplicity, assume a single path.  My assumption in this case was that the 
> SLID/DLID values would be reversed.  That is, the LIDs are relative to the local 
> subnet, not the SGID.  But if I set the SGID = DGID = remote GID, then the LIDs 
> would be relative to the remote subnet.  (Assuming that the local SA could 
> support such a query at all.)
> 
> It seems that in order to meet the requirements of the spec, we need a way to 
> perform inter-subnet queries.  (The alternative being to change the spec...) 
> And if the local SA can return a path record to a remote DGID, then it also 
> seems like the local SA must be able to collect some sort of information about 
> the path to the remote subnet.  (How it does this seems TBD.)
> 
> So... I'm thinking that the solution to these problems should rest within the 
> local SA...

Yes, this seems most consistent with what is there now although there
are some issues to work out on how some of the fields are supported and
which queries would work intersubnet (as well as how they would work).

-- Hal

> - Sean