Re: 2.6 kernel: Cannot make multiple dummy network interfaces

From: Lennart Sorensen
Date: Fri Jun 08 2007 - 13:51:17 EST

On Fri, Jun 08, 2007 at 01:34:16PM -0400, Mike Schmidt wrote:
> (please cc me directly with any responses - I am not (yet) a member of
> this mailing list.
> *2.6 kernel: Cannot make multiple dummy network interfaces*
> ------------------------------------------------------------------------
> I'm trying to set up a number of dummy interfaces but FC6 (Centos4, even
> RHEL4) won't make more than 1. a modprobe -c lists two default dummy
> interfaces, dumm0 and dummy1, just as it did even back to rh8. On my
> rh8/rh9 systems, there is no problem, I can generate as many dummy n as
> I want by adding alias and options lines in modules.conf. On
> FC6/Centos/RHEL (I assume as of kernel 2.6, but I don't have any early
> FC systems running) I can only create 1 dummy. I am trying to build a
> network simulator for testing purposes - a bridge with 100+ network
> interfaces. They have to be dummy (not just an alias) because they need
> separate MAC addresses. I have tried the same thing on Knoppix, running
> 2.6.17, with the same results. Centos4 and RHEL4 use kernel 2.6.9

# modinfo dummy
filename: /lib/modules/2.6.18-4-gx1/kernel/drivers/net/dummy.ko
license: GPL
vermagic: 2.6.18-4-gx1 preempt mod_unload GEODEGX1 gcc-3.3
parm: numdummies:Number of dummy pseudo devices (int)

Perhaps you want to pass that numdummies aregument with some value. The
default may be pretty low.

Len Sorensen
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at