Subject: Problems with wm interface and vlan's
To: None <>
From: Chris Ross <>
List: netbsd-users
Date: 03/01/2005 23:59:22
   I have an i386 machine running NetBSD 2.0.1.  It is running almost 
problem, but the network performance on it is pitiful!

   I have a wm0, with no IP address on it.
   I have 6 vlan interfaces (vlan0 - vlan5) each on wm0, with different 

   An scp from this machine (which is my router) to a host on a directly
attached network (via vlan1) starts at 200+ KB/s, but quickly drops down
to 30 KB/s.  And, it'll flutter around, occasionally stall, and proceed 
20-30 KB/s.  This is silly.

   I tried reconfiguring the machine to use fxp0 instead of wm0 as the 
parent interface, and that works much better.  The same test as above
gets 1.9+ MB/s consistently.

   So, I have two questions:

   1) When I use fxp0, the MTU of the vlan interfaces are 1500, just as 
the mtu on fxp0.  But, when I use wm0, I have to manually set the mtu 
to 1504,
because if I don't, the MTU on the vlan interfaces comes up as 1496 when
they are created.  Why is this different?

   2) What can I do to test what the problem is with my wm0?

   I looked at the Cisco switch it's hooked into (in both cases), and it
does report input errors from the wm.  But, it doesn't indicate what
type they are.  Can I get error counters from the card under NetBSD?
Could it be a software problem in the kernel, or is it a hardware 

   Thanks.  Any help appreciated.

                   - Chris