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

[Kevin Reilly]

Hal and others, thanks for your responses.

This kernel IBAT  looks like it provides the function to map an IP address
of an network interface to the device name and port
number.  My reluctance is i don't think is accessible for the user space
library. We would need to have a kernel model to help
us do the translation. Is there any plans to make it accessible to from
user space?

I would expect that mapped in both directions from the device name used to
open a device to IP address will be very useful for
many reason like debug.

Kevin J. Reilly
STSM, HPC Architecture
-Federation/HPS  Chief Engineer
-HPC interconnect architect
(office) 845-433-7976  (tieline) 8-293-7976



                                                                           
             Hal Rosenstock                                                
             <halr at voltaire.co                                             
             m>                                                         To 
                                       Kevin Reilly/Poughkeepsie/IBM at IBMUS 
             06/21/2005 09:05                                           cc 
             AM                        openib-general at openib.org           
                                                                   Subject 
                                       Re: [openib-general] mapping        
                                       between IP address and device name  
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Hi Kevin,

On Mon, 2005-06-20 at 22:23, Kevin Reilly 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().

With kernel IB Address Translation (IBAT), you can resolve an IP address
(remote or local) and obtain the device and port are obtained from the
ib_route structure.

ib_at_route_by_ip:
 * ib_at_route_by_ip - asynchronously resolve ip route to ib route
 * @dst_ip: destination ip
 * @src_ip: source ip - optional
 * @tos: ip type of service
 * @flags: ib_at_route_flags
 * @ib_route: out structure
 * @async_comp: asynchronous callback structure - optional
 *
 * Resolve the specified dst_ip to a &struct ib_route structure.
 * src_ip can be provided to force specific output interface.
 * flags can be used to select resolving method; currently IB-ARP or ATS.
and then:
 * ib_at_paths_by_route - asynchronously resolve ib route to ib path
records
 * @ib_route: ib route to resolve
 * @mpath_type: ib_at_multipathing_type
 * @path_arr: SA path record array - out
 * @npath: maximal number of paths to return
 * @async_comp: asynchronous callback structure - optional
 *
 * Resolve the specified ib_route to a SA path record array.
 * Number of returned paths will not exceed npath.
 * Multipathing type may be used to obtain redundant paths for APM,
 * other failover schemes, bandwidth aggregation or source based routing.
 * Note that multipathing request is meaningless unless npath is greater
than 1.
 *
 * Returned ib_route structure includes the recommended pkey and qos_tag
for
 * this route.

IBAT is not currently in the OpenIB trunk. See
users/jlentini/linux-kernel/patches/ib_at.h or
branches/shaharf-ibat/src/linux-kernel/infiniband/include/ib_at.h for
more details.

-- Hal

> 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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