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Proper procedure/sequence for an ADSL modem to provide internet to a ethernet router

Hi All,

Never had a problem with this before (hence me not really taking much notice of the 'proper' sequence, as it's always worked fine for me) but now I am! Here's the deal:

I have a Netgear 8 port router which wants it's internet supply via ethernet (and is providing the LAN with DHCP)
I have a broadband supply in the form of ADSL.
So I have a D-LINK (the netgear one worked fine until it died and refused to power on again. it was 1 week old!) ADSL modem (which takes ADSL cable in and gives out broadband via ethernet)

The trouble is that the D-LINK of course (like them all it seems) provides all kinds of extra **** I don't want - such as DHCP.

I have the ADSL modem working fine on its own. i.e. if connected to a computer's NIC it will give the computer a private IP and provide the internet fine. As soon as I jack that into the router however - no internet provided.

OK I thought - let's turn off DHCP on the modem and make sure it has a different subnet to the router. e.g.

if the router is is on let's make the modem on

Still no internet when plugged back into the router.

I normally use the routers with DHCP built in and, because this is a lice environment I'm playing in, I'm not having much time to play with the settings -- so.....

Has anyone come across this before and do they have the optimum settings? Maybe I should make the modem or something with DHCP off?

Any help much appreciated.

P.S. If anyone knows of a router with ADSL modem built in which has 8 ports or more - please let me know!!! Many thanks.
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4 Solutions
leave the modem dhcp on with ip

disable the router dhcp. make the router ip

make the gateway and dns for all devices subnet mask

woops... meant make the router ip!!!!!!!
bigkeeferAuthor Commented:
Cheers Craig!

So the router effectively acts like a switch to the ADSL modem? Dishing out IP's to clients together with the internet.

Makes sense!
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right! you can string many routers along extending the subnet by doing this way... just remember to only have 1 dhcp otherwise things glitch up... let me know how it goes!
bigkeeferAuthor Commented:
Cheers Craig - you're a star!

I'm back on-site first thing in the morning - will let you know how it goes.

Best regards

bigkeeferAuthor Commented:
Hi Craig,

Well - did everything you said - but still no joy. However, I think the D-link side was 'to blame' as, even when connected to just one machine, it would give the Public IP address to the PC (requesting an IP via DHCP) instead of a private one?

I was going to reset to you factory settings on the DLINK - but ran out of time again.

I'm hoping I will have another stab this weekend.
The DLink is in a bridge mode.
Reconfigure it to be a full NAT router with dhcp on the lan side.
Then let the netgear be a switch or just get a separate switch which has no settings to misconfigure.
Wait a minute. Try shutting the modem OFF before you put it into the router..then power it on and into the router, you should get a public ip in the router then..and you dont have to do any configuration.. sometimes the modem has to be shut off..to recognize a new device... so power it off if you switch between router/pc... if you still have dhcp going on 2 devices - shut it off on one of the devices..

lemme know how it goes.,
bigkeeferAuthor Commented:
thanks guys

The problem is my client has lost all faith in IT/hardware as the reason we are struggling with D-LINK is because the Netgear ADSL modem worked fine with the 8 port netgear. Unfortunately it died after 7 days (literally - went off and power never came back on again). It was brand new 7 days ago!

This wouldn't be enough to hack him off to the degree he is now - but unfortunately we have had dead on arrival kit in the past plus 8 port routers that go pop after 8 months etc. I think he's had enough with the whole trade :(

The upshot is that we have falled back to the 4 port router (with built in adsl modem) and a switch. And he's talking about dropping networks altogether in the new year (he's only a small business) and doesn't want to do anything now 'cos it's his busiest time of year.

However, as he has a Windows 2003 SBS. I was wondering if it might be best to pump the ADSL modem straight into one of the NICs on that and then use SBS to pump the internet over to the other clients via the 8 port router?

Only trouble then is that the VPN we use (built into the netgear router) may not work properly as it's not getting its internet source pumped straight into the box??

To go back to the original problem briefly: I did power off the DLINK modem and we still had problems.

The trouble is the router has settings that may be conflicting depending on what the DLINK is doing? e.g. the netgear router asks whether to get its IP address directly from ISP or whether you want to specify it (in which case you need the IP, subnet, DNS).

Now my client has a static IP address. So if the DLINK is giving a public IP - do I set the netgear to get it dynamically? Or specify it specifically?

If however the DLINK goes back to non-bridged mode and dishes out DHCP private IP addys - what do I tell the netgear router then?

And, more importantly, why doesn't anyone sell a ADSL modem that simply JUST pumps the internet rawly into the ethernet jack of these flipping routers??? WHy do they have to all come with DHCP and all this rubbish that nobody wants? (If you did you would surely buy a router with ADSL modem built in)

Surely the only market for these boxes really is to to provide BB for routers that insist on ethernet input??


Your thoughts and input are much appreciated guys (before I go mad)

Although I don't think I'll be able to try them out until my client cools down.
>And, more importantly, why doesn't anyone sell a ADSL modem that simply JUST pumps the internet rawly into the ethernet jack of these flipping routers???

Any modem does that in bridged mode.
Bridged mode makes it more difficult to monitor line statistics collected by the modem.
you mentioned VPN.... how was it configured? it sounds like the vpn configuration is causing it not to work for all machines - you say you can hook the dlink to a pc and it works so the dlink should not be the problem. what are the settings on the netgear?

are you putting the connecting cable into the router wan port from the dlink? or one of the router 1-8 ports? if the wan try the 1-8 ports(crossover may be needed to put in wan port). if the 1-8 try logging onto the router while its disconnected and disabling the dhcp and configuring the subnet/network info. then connecting to the dlink.

BTW = ur client has to remember that the service he is getting is:

1 - low end service and guaranteed to a point (not like a T-1 has 4 hour sla's)
2 - using the least expensive equipment available (soho routers are EASILY replaceable and expected to fail after some time - more expensive equip like a $200 router will not fail nearly as quickly.)
3 - given the limited time and circumstances you are doing the best you can (as far as I can tell)

AND shi*T happens..


could have been someone/anyone in his office resetting the router or tinkering with it...
Olaf De CeusterCommented:
Hello Bifkeefer.
If you are running SBS2003 and from reading between the lines you have more than one NIC on your server (correct me if I am wrong) and your modem works haging directly of a machine I suggest the following.
1> Remove router all together.
2> Hang modem of the second NIC of the SBS Server
3> Make sure your DHCP on the server in running and configured.
4> In the to Do List on the server console: Run the Internet Connection Wizard: http://www.12c4pc.com/sbs2k3/sbs2k3-n2.htm
Heaps of help info on every page if you get confused.

In regards to your VPN: Can't go past the the Remote Access configuration wizard also in the TO DO List. Enter your FQDN or your permanet external IP address.

Seems as you had a bad run with your networking.
You might have blamed it on bad hardware but was it? If you have two DHCP's on your SBS network you will get some starge behaviour to say the least.
1.SBS likes to do its own DHCP
2.If you join the workstations using the connect computer wizard you will probaly never have network issues again and your boss will be happy like a p.g in sh.t.
If you need further help let me know.
Olaf De CeusterCommented:
PS Changing this config should only take you a few minutes.
bigkeeferAuthor Commented:
Hmm. My answer didn't get posted for some reason.

To summarise it: basically thanks a lot for all your help guys!

I never got a chance to redo this as this is my client's busiest time of year and he doesn't want to dabble anymore until at least Feb07. So the old router and switch stay in place until at least then :)

I'll split the points the best I can.

Thanks again.
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