[ofa-general] Ipoib child interfaces are created in dgram mode, even if the config file (and main interface) specify connected mode.

[Eli Cohen]

On Mon, Jun 01, 2009 at 09:01:23AM -0500, Mike Heinz wrote:
> One of our testers recently reported that he was getting different performance numbers from IPOIB depending on whether he was using interface ib0 or  a child interface he had created with /sys/class/netib0/create_child.
> 
> Investigating, I noticed that the two interfaces have different MTU sizes:
> 
> ib0       Link encap:UNSPEC  HWaddr 80-00-00-02-FE-80-00-00-00-00-00-00-00-00-00-00
>           inet addr:172.21.33.58  Bcast:172.21.255.255  Mask:255.255.0.0
>           inet6 addr: fe80::211:7500:ff:8fa4/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:65520  Metric:1
>           RX packets:76 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:23147668 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:256
>           RX bytes:5284 (5.1 Kb)  TX bytes:17365044664 (16560.5 Mb)
> 
> ib0.9001  Link encap:UNSPEC  HWaddr 80-00-00-06-FE-80-00-00-00-00-00-00-00-00-00-00
>           inet addr:172.21.34.58  Bcast:172.21.255.255  Mask:255.255.0.0
>           inet6 addr: fe80::211:7500:ff:8fa4/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:2044  Metric:1
>           RX packets:60413619 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:256
>           RX bytes:112572449188 (107357.4 Mb)  TX bytes:0 (0.0 b)
> 
> 
> This leads me to believe that the child interface is in datagram mode even though the parent is in connected mode.
Probably it is, but you can always check the mode by reading the
corresponding sysfs file:
/sys/class/net/ib0.9001/mode
> 
> Is this expected behavior?
Yes, it is the expected behaviour.

> Is there a way to change this?
> 
Yes, it is possible

> --
> Michael Heinz
> Principal Engineer, Qlogic Corporation
> King of Prussia, Pennsylvania

> _______________________________________________
> general mailing list
> general at lists.openfabrics.org
> http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general
> 
> To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general