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Using Linksys router to add wireless to cable network

By steveavis ·
At home, I'm happily running 2 computers connected together with a switch and connecting to the internet through a Motorola SB5110i Surfboard cable modem.
We've been given a laptop and a Linksys WRT54Gv2.2 wireless broadband router with 4 port switch, and I thought it would be nice if I could use it as a replacement to the existing switch (it's a Linksys BEFSR41 (now I read the label on the back, it's also a router with 4 port switch!)) but with the added benefit of giving the laptop wireless access.

Unfortunately, it doesn't work.
It's nothing to do with MAC addresses.

Apart from that, I'm stumped. I've tried turning off the DHCP server on the modem, thinking that there was a conflict between it & the router, but that didn't fix anything.

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Nothing to do with the MAC addresses?

by 1bn0 In reply to Using Linksys router to a ...

Have you tried spoofing the mac address of one of the computers in the router?

Can't rule it out if you haven't tried it. Don't know if you have unless you tell us.

This has been required for EVERY ROUTER I HAVE EVER CONFIGURED on a cable modem connection.

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Really?

by MGP2 In reply to Nothing to do with the MA ...

I can honestly say I've never had to clone the MAC address for any of my routers for a cable modem. They include both DLink and Linksys.

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depends on the ISP

by Neon Samurai In reply to Really?

It used to be much more popular for the ISP to record the client side MAC and only play nice with it. If the client side MAC suddenly changed, maybe they are "sharing" with a router or someone else popped there own machine on the network.

In the case of Rogers, MAC is recognized but I've never had to do anything more than turn the cable modem off for five minutes then back on. When I boot the client side machine, the modem sees that it is a new bootup and accepts the MAC.

Router's do usually offer the feature to display an assigned MAC so your router can apear to be the ligitimate computer your now placing inside your network.

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Very sure about the MAC...

by steveavis In reply to Nothing to do with the MA ...

Wow! thanks for the quick replys!

The modem's quite happy to play with the switch, or with an individual computer plugged into it (as I'm doing now).

Half a decade ago, I worked for Telewest (now part of Virgin) as a contract installer. We needed to phone through the MAC addresses before they'd connect the modems. They changed this just as I was leaving so no MAC addresses were needed.

The modem's IP is 192.168.100.1, with it's DHCP pool running from 192.168.100.11-42, so I assigned the router as 192.168.100.2, the laptop as ...3 & a desktop as ...4 & turned DHCP off on the router.
both computers could see both modem & router, but neither of them could go online...

The subnet mask assigned by the modem is 225.225.248.0 (I think- that's what ipconfig/all tells me...), while the router will only accept values 225.225.225.x (via a drop down menu). Could this be my problem?

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Confusion

by SundayBiker In reply to Very sure about the MAC.. ...

I think the confusion comes from the fact that your modem is also a router (it has DHCP) and the Linksys is also a router, don't call it a switch. They both assign addresses and might have firewalls active, try to disable all of them on the modem/router and use it only as a modem. Then configure everything on the Linksys router.
Time Warner never had a problem with whatever MAC I used, now I have Cox and it's the same. But I had a friend in Florida that wasn' allowed to use different MACs or have more than one PC connected (of course he connected more behind a router, with one cloned MAC and one IP visible to them).

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Can you clarify some points?

by Neon Samurai In reply to Using Linksys router to a ...

You should be able to hook the Motorola to the coax in the wall. The Linksys WAN port then hooks into the Motorola's client side network port. Your wireless connects by radio frequency whild your wired nodes connect to the Linksys internal network ports. This is basically my exact setup with more client nodes.

My cable modem does not offer any dhcp or try to be a bridge like Bell's issued ISDN modem. I'm not shure how yours is.

My wrt350n gets an external IP issued by Rogers network. If the network has grief with my MAC changing, rebooting the modem then booting the router fixes it.

I then set the wrt350n to provide DHCP service to the internal network. Wired nodes get there IPs with the next reboot.

I then set the wireless to "G only" but pick "n" if you use that instead. Encryption is set to WPA2 with a AES. Wireless nodes connect and get issued valid IP.

That is the minimum; wired need the cable connected, wireless need 11G, WPA and a strong key (minimum).

I mention the Bell ISDN modem. This little unit is an ISDN modem that includes a DHCP server and wireless. That particular connection uses it's own router to manage the network and get the internet feed so all I wanted from the ISDN modem was bridging between Bell's digital line and the network cable.

To get basic functionality out of that misserable ISDN modem, I had to perform some cryptic configurations after diging down about three levels of config forms. There was an archaine setting told the modem to function in "pass through" mode instead of trying to manage the network.

Is your cable modem similar to this where it includes the cable modem and a switching hub with dhcp? If so, confirm if there is a way to set a "pass through" mode on it.

I can't think of anything else that would stop you off the top of my head.

Some questions
- Who is your ISP and are they using your MAC as part of the validation for your connection? Documentation should indicate "recognized MAC" or something which you would then input as the router's faked MAC.

- Where does the connection die? Are you able to connect too and among the nodes on the router but not too the outside network? (is the router getting issued an external IP) Are only your wired nodes getting internet but not your wireless? Can you tell which stage breaks the network connectivity?

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attempt at clarification

by steveavis In reply to Can you clarify some poin ...

Yes, that's the kind of setup I'm after...

The modem's got three sockets- a coax for the connection to the cable network, the RJ45 I'm using & a USB (don't really want to use that, as it only allows for one computer to be connected at a time!). The only adjustment I get on the modem is to disable DHCP.


The modem's IP is 192.168.100.1, with it's DHCP pool running from 192.168.100.11-42, so I assigned the router as 192.168.100.2, the laptop as ...3 & a desktop as ...4 & turned DHCP off on the router.
both computers could see both modem & router, but neither of them could go online...

The subnet mask assigned by the modem is 225.225.248.0 (I think- that's what ipconfig/all tells me...), while the router will only accept values 225.225.225.x (via a drop down menu). Could this be my problem?

(the last two paras copied & pasted from my answer above).

Come to think about it, I had a different computer when the modem was installed, so I'm even surer that the MAC doesn't signify...

How do I tell if the modem's getting an external IP?


I've disconnected the rest of the network- below is the result of one PC connected to the modem (with DHCP enabled on the modem)


ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : SNz123456789
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 3Com 3C920B-EMB-WNM Integrated Fast
Ethernet Controller
Physical Address. . . . . . . . . : 00-11-2F-08-04-B6
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 82.36.210.231
Subnet Mask . . . . . . . . . . . : 255.255.248.0
Default Gateway . . . . . . . . . : 82.36.208.1
DHCP Server . . . . . . . . . . . : 62.30.192.114
DNS Servers . . . . . . . . . . . : 194.168.4.100
194.168.8.100
Lease Obtained. . . . . . . . . . : 08 August 2008 20:53:28
Lease Expires . . . . . . . . . . : 15 August 2008 00:22:01


Does this help?

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Here's your proof...

by MGP2 In reply to attempt at clarification

This is your info assigned by your ISP (whether static or DHCP)
IP Address. . . . . . . . . . . . : 82.36.210.231
Subnet Mask . . . . . . . . . . . : 255.255.248.0
Default Gateway . . . . . . . . . : 82.36.208.1
DHCP Server . . . . . . . . . . . : 62.30.192.114
DNS Servers . . . . . . . . . . . : 194.168.4.100
194.168.8.100

The 192.168.100.1 is a standard cable modem web interface. That's so you can log in and reboot the modem without having to walk to it (depending on where it is).

Here's what I'd do. Turn off DHCP on the cable modem. On the router, use either 192.168.0.1 or 192.168.1.1 for the router address and assign your addresses based on the one you assign to the router. (So, if you use 192.168.1.1, use 192.168.1.2 etc for your desktop, .3 for laptop, etc. Better yet, you can just turn on DHCP on the router and let your laptop and desktop get their info from the router). Use a standard Class C subnet mask of 255.255.255.0. Don't worry about the difference in subnet masks between your network and the subnet assigned by your ISP. That should be all you need to do.

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tried

by steveavis In reply to Here's your proof...

OK, I turned off DHCP on the modem, set the router back to 192.168.1.1, the desktop to 192.168.1.2 & laptop to 192.168.1.3.
Set evrything's subnet mas to 225.225.225.0 (apart from the modem, which I can't change) & copied the DNS Servers & default gateway from the desktop's configuration when everything was set by the modem

This is after all the changes (& the traditional turn everything off/on)-

Host Name . . . . . . . . . . . . : SNa123456789
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 3Com 3C920B-EMB-WNM Integrated Fast
Ethernet Controller
Physical Address. . . . . . . . . : 00-11-2F-08-04-B6
Dhcp Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.1.2
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 82.36.208.1
DNS Servers . . . . . . . . . . . : 194.168.4.100
194.168.8.100

(the laptop is identical, except for the IP address 0f 192.168.100.3)

--

This is the desktop when it worked (just desktop & DCHP on modem)

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 3Com 3C920B-EMB-WNM Integrated Fast
Ethernet Controller
Physical Address. . . . . . . . . : 00-11-2F-08-04-B6
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 82.36.210.231
Subnet Mask . . . . . . . . . . . : 255.255.248.0
Default Gateway . . . . . . . . . : 82.36.208.1
DHCP Server . . . . . . . . . . . : 62.30.192.114
DNS Servers . . . . . . . . . . . : 194.168.4.100
194.168.8.100
Lease Obtained. . . . . . . . . . : 09 August 2008 08:18:58
Lease Expires . . . . . . . . . . : 15 August 2008 00:22:03

--

Both machines can see both the router (on 192.168.1.1) & the modem (on 192.168.100.1).
Neither can see the internet.
Neither can ping the other one's IP address (I'm not sure that's relevent).


I've included 3 screenshots of the router's setup pages. You'll notice that on the router status page, there's no IP address. When I change the basic setip to static IP, I don't know what the internet IP is (surely it'll change everytime I turn on the modem (?).) & any changes I make to it tend to end in me being told that "value is illegal!". The other options are PPPoE, PPTP, L2TP & Telstra Cable, none of which seem likely, as they all require a password & username.


On the Advanced Routing page, if I change the settings to
Destination LAN IP : 192.168.100.1
Subnet Mask : 255.255.255.0 (or 255.255.248.0)
Default Gateway : 82.36.208.1

It returns the message "Invalid LAN IP or subnet mask!".

The Router setting on the advanced routing page was initally set to gateway, but I've changed that.

Images:

http://www.b3tards.com/u/f4ab7769a7adfa5fe1dc/router_status1.gif
http://www.b3tards.com/u/f4ab7769a7adfa5fe1dc/basic_setup1.gif
http://www.b3tards.com/u/f4ab7769a7adfa5fe1dc/advanced_routing1.gif
http://www.b3tards.com/u/f4ab7769a7adfa5fe1dc/basic_setup_static.gif - this is the screen for a static address

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Maybe you can not access the internet because you are not using PPPOE..

by Peconet Tietokoneet-217038187993258194678069903632 In reply to tried

"The other options are PPPoE, PPTP, L2TP & Telstra Cable, none of which seem likely, as they all require a password & username."

You will have to check this out with your ISP to determine which line you have, when you have found that out then you will be able to select this in your Router. Some ISP's recommend that "DHCP" is marked "enable" in your router. From there you will have to set up the connection with your computers one by one, you will need a User name and password to access the internet. As for a User name and password for your router is a good choice also, Unless it is static on Admin for your User name, but the password you should put in your router to lock it down.

Please post back if you have any more problems or questions.

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