Multiple Router Setup

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roberth

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Thanks in advance for the help, I have tried to find the solution by googling the problem but can't seem to get an answer which I understand.

For complicated reasons I have ended up with 3 routers. Lets call them "1", "2" and "3".
"1" is a LAN only D-Link router, connected to the telephone line (I have set the IP to 192.168.0.1).
"2" is also a D-Link but has wireless as well, and is connected to "1" via network cable (IP set to 192.168.0.2).
"3" is a NetGear N300 with wireless, and is connected to "1" via network cable (IP set to 192.168.0.3).

"1" is setup in half-bridge mode so I can either just plug in and surf the net or dial to another account.
Now I have got "1" and "2" working together perfectly. Any device connected by cable to "1" or "2" can surf the net or dial another ISP. And any wireless device connected to "2" can surf the net.
But I cannot get "3" to work properly. I think I need to set it's default gateway to 192.168.0.1 but I don't know how. As it is currently an internet connection through "3" comes and goes randomly, especially for devices physically plugged into it. Mostly there is no internet available.

The only place I could find that I can specify a gateway is in creating a "static route" but I don't know what the difference between the destination address and gateway address is, and it won't let me set the destination gateway to 192.168.0.1 (it changes it to 192.168.0.0 automatically).

I think I just don't know enough about what i'm doing. I don't know what DNS, ATM, IPoA, NAT are so I don't know what to fill in there ot if they should be on auto.
If anybody could help me I would greatly appreciate it.


More Info:

Router 1 = Router connected to telephone line: 192.168.0.1
Router 2 = Wireless Router downstairs: 192.168.0.2
Router 3 = Wireless Router upstairs: 192.168.0.3
Reserved for other (future) routers: 192.168.0.4-9

IP Range reserved for computers connected to Router 1: 192.168.0.10-49
IP Range reserved for computers connected to Router 2: 192.168.0.50-99
IP Range reserved for computers connected to Router 3: 192.168.0.100-149
Therefore enable DHCP server, giving out the above ranges

Default gateway for all routers/connecting devices: 192.168.0.1 (Router connecting to internet)
 
Try to make Router 3, DNS or Gateway 192.168.0.1

Edit: does router 3 work?
 
Last edited:
So are you saying that you've enabled DHCP on each of the routers, but assigned different DHCP ranges for each router to hand out? If this is true, then I think I understand your problem.

First up, you need to understand what DHCP is. DHCP is a protocol which responds to the requests
of devices connecting to a network. The requests ask for an IP addresses, and related network information, like DNS Server (primary + secondary), default gateway (the IP address of the device that knows how to reach the internet), subnet mask, and a few other things.

You should only have one DHCP server on your network, especially for a network of such a small size, and especially if you don't understand much about networking. Having 3 different DHCP servers is unnecessary, and is part of what is causing the confusion. Now, the 2 D-Link routers allow you to specify in the DHCP settings what default gateway they must each dish out to PC's requesting an IP address and network info. However, the Netgear router won't allow you to do this. This is a limitation of the firmware on the Netgear router, and is present in almost all Netgear consumer grade routers. The Netgear router always assumes that it is the default gateway, and doesn't allow you to configure any other value in the DHCP settings. Thus, it advertises to anyone that asks, that it is the default gateway, i.e. it knows how to get to the internet, when in fact it can't. It doesn't have a direct connection to the internet.

The 2nd part of the problem is that you have 3 DHCP servers on your network (one on each router), and each time a PC connects to your network, it will broadcast a request on the network - "can someone please give me an IP address, and related network info. However, since you have 3 DHCP servers on the network, they will ALL respond. You now end up with a race condition. Whoever responds first will be the winner, so the PC will accept the IP address and network info from the DHCP server that responds first. Sometimes the D-Link DHCP servers win and everything works nicely, and sometimes the Netgear DHCP server wins, and then you have problems because your PC now has the incorrect IP address for the default gateway.

Devices connecting directly to any a particular router, will most likely receive the DHCP responses from that router first, since this is the shortest path between the DHCP server and the PC making the request (a direct connection). Example: devices connecting to the Netgear router, will most likely receive the DHCP responses from the Netgear DHCP serve. Occasionally, this is not true, due to packet queues and network traffic causing slight delays on your network, and so devices connecting to a particular router will receive a response from a DHCP server on another router first.

The solution - disable DHCP on your Netgear, as well as on your D-Link wireless router. Keep DHCP enabled only on the wired D-Link router. Problem solved. Only one device is in charge of handing out IP addresses and network information, and this devices also happens to know how to get onto the internet (it has a direct connection to it via your ADSL line). Also, if you ever need to change DHCP settings, you change it in ONE place. Not 3.

BTW, some terminology: Your D-Link wired router is acting as a modem and a router. The other 2 devices are not doing any actual routing, they are just acting as Wireless Access Points, and switches.

Hope this helps.
 
Last edited:
Solution:

Router 1 = Router connected to telephone line: 192.168.0.1
DHCP = ON (Range = 192.168.0.10 - 192.168.0.149)

Router 2 = Wireless Router downstairs: 192.168.0.2
DHCP = OFF

Router 3 = Wireless Router upstairs: 192.168.0.3
DHCP = OFF

Default gateway for all routers/connecting devices: 192.168.0.1 (Router connecting to internet)

Basically what Saajid said above.
 
I really wish a bit more about networking! I knew the above info but and still have problems from time to time! But I think mines more just ****ty hardware and a Kak ADSL connection more than anything else!

Hope you manage to fix with the above solution!
 
Saajid said:
So are you saying that you've enabled DHCP on each of the routers, but assigned different DHCP ranges for each router to hand out? If this is true, then I think I understand your problem.

...
Click to expand...

Awesome. I haven't had a chance to check for responses until now so I will still need to make the changes you suggest, but it certainly makes sense.
Thanks so much for the help, I will let you know if (or when) this works.


cant you "re-work" your set up with just two router?
Click to expand...

All the routers have 4 ports and we need 5 downstairs (hence the 2 D-Link routers downstairs) and wireless upstairs (the NetGear).
If we had known how the network needs would grow we could have catered by buying a big switch or router with more ports but I am basically trying to make do with the equipment we have.
 
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