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Date:  Mon, 18 Oct 2004 00:28:34 +0200
Sender: os2-wireless_users-owner <os2-wireless_users-owner@2rosenthals.com>
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From:  Christian Langanke <os2-wireless_users@2rosenthals.com>
To:  os2-wireless_users@2rosenthals.com
Subject: [OS2Wireless] Wireless LAN Monitor vs wired/wireless cmd files


Hi,

I think one is pretty safe on that. I have thought about some "senseful 
prerequisites" that make sense to take and may not be clear to everyone. 
This does not mean that everything must always be obeyed, but not 
following a rule may give you some problems where you don't expect it.

(1)  if the wired interface and the wifi interface connect to the same 
network via DHCP, it is recommended that only one of either cable or 
wireless card may be available/active/plugged,  _not both at once_. 
Otherwise you end up having two nics with an IP address in one IP 
subsegment, where the TCP/IP stack will use only one of them (that to my 
knowledge cannot be influenced) and this must not necessarily be the 
faster one (the cabled one). So in such cases it is better to (manually) 
decide for the faster interface by pulling the XWLAN card or 
deactivating radio for built-in devices
(BTW the development version already has a startup option property to 
unconditionally start XWLAN with radio off - this is thought to be 
useful for built-in devices in such (and other) scenarios).

(2) the IP interface bound to the wifi nic is _not_ configured in the 
TCP/IP LAN configuration program (does not make sense in most cases 
anyway...)

(3) if your cabled interface needs to be configured statically within 
theTCP/IP LAN configuration program: it should not be configured to an 
IP subsegment that may be used by _any_ wireless LAN you connect to 
using DHCP (same problem as in first case, but here it gets worse!). As 
you cannot know that for unknown WLANs: ff you let DHCP configure your 
LAN nic through XWLAN, have alook at the tooltip text after having 
received the IP config. If the IP subsegment is the same as configured 
for the cable one, you may be in trouble and it _may_ not work unless 
you execute "ifconig lanx down" for the cabled interface. (it may make 
sense to implement a kind of conflict detection within XWLAN, taking 
place after a DHCP configuration has succeeded)

BTW, I never thought about requiring any scripts, so I may never thought 
much about what may be necessary. If there are serious 
reasons/requirements, I could well think of implementing 
startup/shutdown scripts being run after manual/DHCP config before 
startup and before switching to another profile. But IMHO these should 
be very important requirements, as I see some drawback in making the 
configuration options more and more complex. Ideas/Suggestions of 
everybody are very welcome.

thanx, Christian

-------------------------------------------------

Christian Langanke
COS2E & CWSE
Team OS/2 Ruhr e.V.
cla@clanganke.de



Lewis G Rosenthal wrote:

> In my further test setups for class next week, I've been playing with 
> wired/wireless configurations. What I've found is that by using 
> Christian's utility, it isn't really necessary to use scripts for 
> bringing down the wired interface. Interestingly, the wired NIC comes 
> up first using DHCP, and then XWLAN brings up the WiFi card and 
> enables DHCP for that. Both interfaces remain active. I haven't yet 
> actually tested the individual connections (I was testing while 
> docked, and never actually pulled the cable from the dock), but this 
> seems infinitely easier than fussing with different scripts to bring 
> the interfaces down and up.
>
> Any thoughts along these lines?
>


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