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Network Subnetting Question

I have a question relating to subnetting a network. Basically our product (which is basically separate computers on heavy vehicles and equipment) has gone from being a custom embedded computer using Data over voice radio, to off the shelf computer equipment using WLAN.
Our current setup uses separate IP numbers for each and every component in the system. We want to reorganise this if we can to have the IO modules (see below) of our system use the same IP’s but in a private subnet. (This will of course simplify swap outs of components)
So for example, we’d like something like this

HARDWARE ON EQUIPMENT A
Tablet PC (10.0.17.x:16 & 192.168.0.x:16)
Ethernet-2-Serial (192.168.1.1:16)
Ethernet-2-DigitalIO (192.168.1.2:16)
Wireless Bridge (10.0.1.x:16)

HARDWARE ON EQUIPMENT B
Tablet PC (10.0.17.y:16 & 192.168.0.y:16)
Ethernet-2-Serial (192.168.1.1:16)
Ethernet-2-DigitalIO (192.168.1.2:16)
Wireless Bridge (10.0.1.y:16)

So the question is, would the average WLAN bridge stop packets from say Hardware A’s Tablet PC to Hardware B’s Ethernet-2-serial converter since it has the same IP number as it’s own Ethernet-2-serial device.
I tested this afternoon and it seemed to cause issues with the Ethernet-2-serial modules we are using. However, I did have the WLAN bridges I was using in Ad-hoc mode not infrastructure mode (I was/am going to test this tomorrow but thought to ask here too)
If this can’t be done solely with sub netting, I’m assuming we would need a smarter WLAN Bridge/Router than can stop communication to 192.168.x.0 network over the WLAN.

I hope this makes sense and if anyone could shed some light on a solution that would be great.

Thanks
gommo Send private email
Monday, October 09, 2006
 
 
"So the question is, would the average WLAN bridge stop packets from say Hardware A’s Tablet PC to Hardware B’s Ethernet-2-serial converter since it has the same IP number as it’s own Ethernet-2-serial device."

No.  Access Points (APs) don't care about IP.  APs act as bridges to bridge MAC frames (Ethernet).  APs are not routers, generally speaking.

However, the two subnets won't see each other unless you route between them.  Static routing involves a router and route statements on each device's IP stack to tell it about the router that will get them to the other subnet.

It's not your AP that's blocking the traffic but your lack of route information that would stop this.
~Eric
Monday, October 09, 2006
 
 
> Access Points (APs) don't care about IP.

Not all APs or at L2, some are at L3.
son of parnas
Monday, October 09, 2006
 
 
"It's not your AP that's blocking the traffic but your lack of route information that would stop this."

Thats the thing, it doesn't seem to be blocking anything as such. I'd love it too, but by the sounds of it I'll need some additional piece of hardware to do the routing.?

Thanks
gommo Send private email
Monday, October 09, 2006
 
 
"Not all APs or at L2, some are at L3."

That's why I said generally speaking.  Most APs that I've worked with don't route and I've worked with a fair amount of APs and have done many public hot-spots.

@gommo:

Right, bridges operate at a different, lower, level.  Bridges don't care about IP addresses which is the reason it "works" as you see it.  You are basically putting two subnets on the same network (or two collision domains to be exact).

You can block this at the bridge by filtering by MAC address.  You could also disable the bridge and route instead if your device can do that?
~Eric
Monday, October 23, 2006
 
 

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