[openib-general] RE: Re: RDMA Generic Connection Management

[Caitlin Bestler]

> -----Original Message-----
> From: Michael S. Tsirkin [mailto:mst at mellanox.co.il] 
> Sent: Monday, August 29, 2005 1:46 PM
> To: Caitlin Bestler
> Cc: Roland Dreier; openib-general at openib.org
> Subject: Re: Re: RDMA Generic Connection Management
> 
> Quoting Caitlin Bestler <caitlinb at broadcom.com>:
> > > APM might be one good reason to want to get more than one path, 
> > > would it not?
> >
> > But you would have to define automatic path migration in 
> > generic/transport neutral terms. I've actually come up with
> 
> I dont see a problem.
> 
> For the sake of this argument, lets assume APM cant be done 
> with iWARP.
> How is an iWARP card different from an HCA on a fabric where 
> there's only a single path to a specific node then?
> 

There is a very important difference.

The iWARP card *can* support automatic path migration
that is not visible to the RDMA layer -- i.e.,it can
move an L3 address to a new L2 address (port migration).

As such it is very different from an IB device where
all path migration that exists is visible.

Making it even more complex iWARP/SCTP could support
both L4 and L3 migration.