[ILUG] Re: Strange problem with WiFi cards

[Paul Jakma]

On Sat, 26 Mar 2005, Paul Jakma wrote:

> scripts based on link-state, but has some problems) or the 'zebra' 
> daemon from Quagga (which can't run scripts, but can easily be 
> configured to manage your default route according to which 
> interfaces are present and your preferences for which order 
> interfaces should be used).

Oh to accomplish it with zebra, install Quagga, eg

 	(apt-get|yum|pkg-get) install quagga

Edit zebra.conf (might be in /etc/quagga/zebra.conf, depends on where 
the package put it) and if you have, eg an ethernet interface (call 
it eth0) and a wlan interface (eg eth1), and your gateway on the 
ethernet interface is the IP address <eth0 gateway address> and on 
the wlan interface <eth1 gateway address>, and you prefer the 
eth0 ethernet interface to be used, if available, then put the 
following in zebra.conf:

  ip route 0.0.0.0/0 <eth0 gateway address> 1
  ip route 0.0.0.0/0 <eth1 gateway address> 2

This requires:

- Your drivers to properly reflect link-state in the IFF_RUNNING
   interface flag. All modern/good drivers should do this, at least
   ethernet drivers on Linux and Solaris do. I'm not sure wifi drivers
   are as mature yet though (whether they toggle IFF_RUNNING according
   to whether they are associated with an AP).

You can see the 'RUNNING' flag with 'ifconfig', the Linux 'ip' tool 
for some odd and bogus reason does not print out this flag.

- Your ethernet and wlan networks to be distinct subnets, with
   distinct gateways (so that zebra can change the default).

   If the two access the same logical IP subnet, then the above wont
   work due to the kernels installing yet not bothering to manage
   'connected' routes according to link-state. There is a patch
   pending to allow zebra to manage these, which would allow this to
   work, in which case the configuration would simply be:

   ip route 0.0.0.0/0 <gateway>

- That you do not have a default route installed by anything else but
   zebra. (ie not DHCP, not by your OS startup scripts).

regards,
-- 
Paul Jakma	paul at clubi.ie	paul at jakma.org	Key ID: 64A2FF6A
Fortune:
Accordion, n.:
 	A bagpipe with pleats.