[openib-general] mapping between IP address and device name

[Hal Rosenstock]

On Tue, 2005-06-21 at 11:44, Caitlin Bestler wrote:
> Expanding slightly on Hal's response, the correct method to correlate
> an *IP* address with a device is to consult the *IP* routing tables.

> While there are exceptions where you want to control the local
> address,

With IBAT there is a way to force the local interface if that is what is
desired.

> it is far more common that you need to reach a remote
> address (or be reachable from a remote address), as pointed out
> in Roland's response. So the general algorithm is to check the
> local routing tables to see what device would be the first hop.

That's the basic algorithm which IBAT (and SDP) use.

-- Hal

> >From there it is merely a matter of connecting the device
> declared for purposes of IP routing with the device that provides
> RDMA services.
> 
> As for the differences between *IP* and *IB* addresses, that
> boils down to a determination of who is responsible for reconciling
> the difference: the network stack or the application.
> 
> 
>  
> On 6/20/05, Kevin Reilly <kjreilly at us.ibm.com> wrote:
> > 
> > 
> > 
> > 
> > Maybe somebody could help me understand the proper way to map between an IP
> > address assigned to a port to the
> > "device  name" and "port number" in the gen2 architecture.  If I have an IP
> > address can I map it to a name that i get back
> > from ibv_get_device_name() or pass to ibv_open_device().
> >      Here  is  the  problem.  Let's  say  there  is  a  subsystem that used
> > heartbeating over IP interfaces to ascertain the adapters
> > and  ports  state,  up  or  down.   The  data  actively  maintained be this
> > heartbeating subsystem is used by a job scheduler that
> > desires  to  only schedule tasks on HCAs that are UP and have active ports.
> > The job scheduler does not want to launch jobs
> > on adapters that are broken, not connected to a switch or not configured.
> >       The  job  scheduler  needs a way to map an IP address into a name and
> > port number sitable to be passed to the job to
> > use   when   ibv_open_device()   is  called  or  to  match  the  output  of
> > ibv_get_device_name().
> > 
> > Kevin J. Reilly
> > STSM, HPC Architecture
> > -Federation/HPS  Chief Engineer
> > -HPC interconnect architect
> > (office) 845-433-7976  (tieline) 8-293-7976
> > 
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