LAN / IP conflict.

Lydesia

Grr i build machines but internet confuses me sometimes.
I bought this of komplett:

http://www.komplett.ie/k/ki.asp?sku=304347&cks=PLS

Connected my router to it and set it up. Looks fine, all LED's are lighting uop where they are suppose to. Anways, when i connect with the router directly it keeps saying

"Warning: Your Internet IP address falls in the same subnet as your LAN IP address. Click here to change your LAN IP address"

I try and change my LAN ip address but cant seem to, and am really confused about the whole thing really. I cant connect to the internet, thats all i know. Any advice?

Mr. Presentable

Sorry, I killed my previous reply.

Your modem should get a dynamic IP from your ISP, the router is part of your network and most likely has a 192.168.x.x address. Your subnet will fall in the range 255.255.255.x, this for both router and PC.

What is your modem/ISP, and router?

Lydesia

spannerhead wrote:

Sorry, I killed my previous reply.

Your modem should get a dynamic IP from your ISP, the router is part of your network and most likely has a 192.168.x.x address. Your subnet will fall in the range 255.255.255.x, this for both router and PC.

What is your modem/ISP, and router?

Im really confused about this address stuff.
Im on IOL-BB and i have the Zyxel DSL/Router.
Pretty cool router, never given me any hassle.

Anyways i have that plugged into the 3com one, and the Zygel one has the dsl line. So my PC is connected to one of the 3com's LAN slots.
One PC is ready with the wireless connection too

Mr. Presentable

Is the 3com another router, or just a hub?

Lydesia

spannerhead wrote:

Is the 3com another router, or just a hub?

lol, a hub i think? (a cable/DSL gateway apparently)

Mr. Presentable

OK, my immediate suggestion is

change your TCP/IP properties to "obtain an IP address automatically" on the PC. Then shut it down. Shut down the modem, router and 3com. Now, starting with the modem and working inwards from the wall towards the PC, turn one piece on every 30 seconds, leaving the PC untill last, of course.

I know that sounds mad, but it may just work. Not being able to actually see your config makes it harder to analyze.....

Moriarty

Moved over to Nets/Comms.

tomk

The core of the problem here is that you now have two routers, and you only need one. Your ZyXEL gets an ISP-assigned public IP address on its external (WAN) interface, and uses NAT (Network Address Translation) to communicate between that address and a private IP address range on internal (LAN) interface, typically 192.168.x.x, with a subnet mask of 255.255.255.0.

The 3Com does a very similar job, except without DSL functionality. It is expecting a public IP address on its external interface, and again NATting that to a private subnet on its internal interface, or interfaces in this case - wired and wireless.

What's happened here is that the 3Com is getting a private IP address from the ZyXEL on its external interface, which happens to be in the same private address range as the 3Com want to use on its internal interface i.e. the one that will be connected to your PC/laptop/etc.

Change the internal address range on the 3Com - the "LAN IP address" referred to in the error message - to a completely different private range, say 10.0.0.0, subnet mask 255.255.255.0. Make sure your PCs, laptops, etc are setup to get their addresses by DHCP, and turn on DHCP on the 3Com. That should get you on the net, at least.

Ideally, though, you should disable the router part of one of the boxes, because the setup I have described is known as a double-NAT configuration, which in simple terms means that there are two private networks between you and the internet. This can cause problems for some internet applications, although I should say that for general surfing etc you will be fine.

Have a look on the ZyXEL or in its manual for any mention of "bridging" or "RFC 1483/2684" or anything similar. If it's there, it will effectively turn the ZyXEL into a plain DSL/ethernet modem, which will deliver the ISP's public address to the 3Com's external interface.

Alternatively, see if there's any way of turning off or bypassing the 3Com's router function, so that it operates as a simple access point instead.

Lydesia

tomk wrote:

The core of the problem here is that you now have two routers, and you only need one. Your ZyXEL gets an ISP-assigned public IP address on its external (WAN) interface, and uses NAT (Network Address Translation) to communicate between that address and a private IP address range on internal (LAN) interface, typically 192.168.x.x, with a subnet mask of 255.255.255.0.

The 3Com does a very similar job, except without DSL functionality. It is expecting a public IP address on its external interface, and again NATting that to a private subnet on its internal interface, or interfaces in this case - wired and wireless.

What's happened here is that the 3Com is getting a private IP address from the ZyXEL on its external interface, which happens to be in the same private address range as the 3Com want to use on its internal interface i.e. the one that will be connected to your PC/laptop/etc.

Change the internal address range on the 3Com - the "LAN IP address" referred to in the error message - to a completely different private range, say 10.0.0.0, subnet mask 255.255.255.0. Make sure your PCs, laptops, etc are setup to get their addresses by DHCP, and turn on DHCP on the 3Com. That should get you on the net, at least.

Ideally, though, you should disable the router part of one of the boxes, because the setup I have described is known as a double-NAT configuration, which in simple terms means that there are two private networks between you and the internet. This can cause problems for some internet applications, although I should say that for general surfing etc you will be fine.

Have a look on the ZyXEL or in its manual for any mention of "bridging" or "RFC 1483/2684" or anything similar. If it's there, it will effectively turn the ZyXEL into a plain DSL/ethernet modem, which will deliver the ISP's public address to the 3Com's external interface.

Alternatively, see if there's any way of turning off or bypassing the 3Com's router function, so that it operates as a simple access point instead.

Cheers for the reply and i understand mostly what your saying.
but im still going MAD :mad:

I changed the LAN address like you said to "10.0.0.0" but i told me the last number could not be 0. Anyway so i changed it to 10.0.0.1

Now i cannot communicate with the router. It wont pick up on this or its older one.

Whats really pissing me off though is that even if i connect the ethernet cable to the 3com, i should still get interent access through the Zyxel because its also connected to my machine via USB. But i lose that connection too, so wtf is going on? I also cannot find the manual for that router.

The set up i need is simply interent access to a computer in a room just down the hall from me. i have the USB reciever that came with the 3com, is their anyway i can transmit from this to the hub, then i could connect the hub to the other machine. GHVGUBH DAMN I hate this crap.

tomk

Right, let's try a few more things.

Check that your PC is configured for DHCP. Power off and disconnect everything. Connect your PC to the 3Com via ethernet, then power up the 3Com, wait 20-30 seconds, and power up the PC.

On the PC, open a command window and enter

ipconfig /all

If the IP address is 10.0.0.x, the change of LAN address on the 3Com has been successful, otherwise it needs to be done again. To do it again, open the 3Com GUI in your browser, and do what you did before. Make sure that DHCP is activated, and click the "Save" button, or whatever it may be called. Then enter

ipconfig /renew

in the PC command window to get a new IP address.

Go to the 3Com GUI again (using http://10.0.0.1 this time) and configure the external interface to use DHCP - it needs to do that to get an address from the ZyXEL. Again, make sure to click "Save" or the equivalent. There may also be an overall "Save configuration" somewhere that needs to be clicked.

Connect the 3Com external interface to the ZyXEL internal interface. Power up the ZyXEL. If the 3Com has a "renew" function for its external interface, activate it - otherwise, power-cycle the 3Com. In the 3Com GUI, check the address that has been assigned to the external interface - it should be 192.168.1.x.

From your command window, you should now be able to ping all of the following:

10.0.0.1 - 3Com internal address
192.168.1.x - 3Com external address
192.168.1.1 - ZyXEL internal address (I'm not sure if it's .1 at the end - if you get no response try .254, and if you still get nothing don't worry)

Finally reconnect the ZyXEL to the phone socket. It may be necessary to power-cycle the ZyXEL to reactivate DSL - I don't use it, so I'm not sure.

Hold your breath, and try pinging www.boards.ie in your command window. It should respond. If not try pinging 82.195.144.58. If you get a response, you have a DNS issue, which we can cover if necessary.

I'd better go do some work now - try this much first, and let me know how it goes.

One last thing - patience is everything. Once you get the hang of this stuff, you'll be fine. I can guarantee you that I'd feel the same if I was asked to build a PC!

Lydesia

Your help and the time you have given to me i truely appreciate.
I followed step by step what you told me and its working!

Thank you so much.
However a new problem has arisen, and i will completly understand if you dont have the time.

My wireless link is now not working at all. And it was working before i fixed the previous problem, so basically im still at Step 1, because i need the wireless connection to the computer down the hall. Its connected with the supplied USB stick.
I turned all encryption off and set to the default channels ect, windows says it has 'Limited or no connetivity' and the 3com program freezes while trying to pick it up.

any ideas?