Mediacom → Adding Wireless Router

My sister has Mediacom. Of course, I'm enlisted to add a WLAN to her house. I realize Mediacom supplies a wireless modem for additional charge but that is not what she wants to do.

I added a Linksys WRT54g wireless router to the modem. Used MAC cloning to simulate her one computer that was plugged into the mediacom modem. Using DHCP in the Linksys. Used subnet 1 for the local LAN. Computers hardwired to the Linksys router work, and are assigned correct addresses in the correct range. Everything is fine.

Computers connecting wirelessly are assigned addresses that appear to be in a range from the Mediacom modem....Kinda weird. In any case, they are incorrect and thus the wireless network does not work, even though the wired one does. I've power cycled the equipment so everything should have "taken". I can ping through to the router OK on hardwired, but on wireless, the IPs are screwed up so no connection....

Anyone have any thoughts as to what I am overlooking here.....

I'm fairly experienced at networking, but not at interfacing to Mediacom (or other cable) modems. I'm obviously overlooking something simple.

I assume you've connected to the administration pages on the wireless router (192.168.1.1) and made sure everything is good there? I can't recall if there is a setting there you need to check on or off as to DHCP on the wireless side separate from DHCP usage altogether.

ADDED: You might want to try a complete reset of the unit using the reset button in back to get it back to factory settings, where it should work right out of the box for both wired and wireless DHCP. Then add back in your settings for SSID, wireless passkey, changing the administrator's password, etc.

Thanks for the reply. There is no separate DHCP setting for just the wireless side. I do think that resetting to factory and starting over is the only way to proceed at this point. I also have a Belkin wireless router I can try. It may just be a funky Linksys router - although that particular router has worked fine in the past.... I've learned the hard way that these consumer routers have strange things going on at times....

I was hoping I was just doing/overlooking something obvious, though.

i have a wrt54gl i flashed it to tomato and havent used the linksys firmware in ages. that said heres my setup.

192.168.100.1 modem - sbv5220
192.168.1.1 router

DHCP in router = on
wireless set to accesspoint.

you do NOT need to clone the mac address. id suggest resetting both and trying again. as connecting the router to the cable modem on modem startup works just fine with no need to clone the mac address.

On the MAC cloning....am I hearing correctly that the Mediacom router does not have the PC network card MAC somehow hardwired into it? That it detects the connected device each time it boots? So MAC cloning is not required....right? Thanks for the help. I'll try all that. Unfortunately, I have to drive 45 min each time I try this stuff...(but that's MY problem )

pretty much, mediacom as far as i can tell does not "lock" service to a mac. best bet would be to unplug the modem (remove its battery if it has one) wait eh 15 minutes. plug the router in to the modem and start up. mac cloning is not needed.

i may be getting my terms wrong here but basically the modem would act as a bridge, the router would get its ip from mediacom, and every thing behind the router should get its ip from the router (192's) im no pro, and this is just a guess. but im thinking some how the mac cloning is whats causing your problems of wireless getting mediacom assigned ip's (how exactly im not sure)

Thanks, I think you are on to something, here. I'll try that tomorrow night and see what happens. I'll post the results.

Unfortunately for my sister, this is the only shot she gets at me doing this. I'm leaving the area on Saturday. So it is going to work tomorrow, or not at all. She can pay Mediacom for their wireless router if this does not work

The original poster's problem is not the MAC cloning. I still have my router doing a MAC clone, but only because I'm lazy and haven't removed it. MAC cloning goes back to about 7 years ago when Mediacom did tie your connection to the MAC address of the PC you had the modem connected to. Shortly after that they did away with that bit, when they began to support (even promote) home networking. So "thedragonmas" is also right in that MAC cloning is no longer necessary.

I'm at work, so I can't check my WRT54G, but I am vaguely recalling that, depending on the version of firmware the OP has in his wireless router, one used to be able to specify a range of DHCP addresses to assign for wireless users separate from those assigned for wired. It could be that something was messed up there. On the other hand, I could be remembering incorrectly.

Try to setup the wireless as open (no security). If that works you know that the security is the issue.

Some network cards don't work with WPA2 ( I have a Vista ACER laptop that doesn't work with WPA2). I would suggest starting with WEP, then WPA and see if you can get one to work.

Some modems can provide DHCP 192.168.100.x range, especially before they obtain block synch (DHCP requests should be forwarded to the Mediacom DHCP servers at that point).

Just a quick question which may or may not have any bearing on your issue. Do you happen to have the modem plugged into a switch port instead of the WAN port? It could possibly explain why you might be getting DHCP assignments out of the 192.168.100.x range instead of the configured subnet for the Linksys router.

Since you mentioned that the wired connections work, I'm guessing that this is probably not the issue. I thought it was worth mentioning just in case.

Another thing to look at is to make sure that the wireless connection drops when you power cycle the router, to ensure you are connected to the correct wireless AP.

Good luck with the troubleshooting!

Further info:
- modem is plugged correctly into the router WAN port. And works fine on wired connections. Local wired connections are properly plugged into the LAN ports. I've had three machines running this way.
- DHCP for the router is enabled and I'm using .100 for the start, plus 50 addresses. The router properly assigns IPs starting at 100. IPCONFIG confirms that.
- the routers address is configured as 192.168.1.1 and I can ping that fine on the wired connections - and that is consistent with the IPs being assigned them.
- the wireless clients connect to the router fine, but the IPs assigned are in a totally different address block. I'm "assuming" that is flowing from mediacom, but do not know that for a fact.
- all clients are set to acquire everything automagically. Nothing is hard configured in any client devices.
- I have WEP security set (yes, I know....:(), because I have no knowledge of the age of the connecting devices. OLD, I'm sure.

If mediacom IS supplying 192.168.100.x addresses through the modem that is not good. I'll have to look at that and see. I never would have thought that.

I'll check for different ranges for wired/wireless on the DHCP. I don't ever recall Linksys doing that, but I could be very wrong. On edit - there is only one place to set up the DHCP ranges.

I agree about resetting to factory, no security, kill the MAC cloning and starting over. I'll also move the DHCP ranges away from 100 and check the router WAN side.

Thanks, guys....

I bypassed all of this when I tried the MC HSI. I purchased a Motorola Wireless Modem (SBG900) and it worked great.. The Modem worked fine, the Service well that's another story.

Cable modems unless they have a built in router will not give out DHCP. You will be connected with your given 173. or 50. ip. Reset your router back to default settings. No reason to change what IP range you get. DO NOT CLONE YOUR MAC. No reason too. Once you reset everything and enable wireless your wireless should connect.

It doesn't have to have a built in router. Look up the Motorola SB5100 as they do have an internal DHCP server:

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The Cable Modem has three active interfaces, the HFC, the Ethernet and the USB and each interface has both a MAC and an IP address associated with it. When operating normally it is the IP address of the HFC interface that is used for diagnostic access to the modem. However the IP address associated with the Ethernet interface is always available to the client side network, unless it has been disabled by management command. This means that a PC on the client side can access the WEB pages within the modem using the reserved address 192.168.100.1. This is a non-routed address so it cannot be reached from the Internet (routed) side of the network.

The SB5100 family of modems contain an internal DHCP server, which is active until the modem registers with the CMTS. In the case of a problem that prevents the modem from completing its registration, the modem can still give an IP address to the client PC to enable diagnostics access. This address is given with a very short lease (around 10 seconds) so that as soon as the registration does complete the client PC obtains its proper IP address from the core network DHCP server.

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I have one and its not active once it registers.

Yes. That's what part of the above message said:

quote:

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The SB5100 family of modems contain an internal DHCP server, which is active until the modem registers with the CMTS.

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I was pointing out that you don't need a built in router for the cable modem to function as a DHCP server as it does have the ability to do so and does operate until X condition.

You did set a unique SSID and make sure you aren't connecting to a neighbor's unsecured network? I'm assuming you entered the WEP key and connected to the correct router, but I have to ask.

Does the router have the default firmware or something like DD-WRT? DD-WRT does support multiple DHCP server scopes, so it is possible an old DD-WRT configuration had a separate scope set up for the wireless clients.

The IP shouldn't be coming through the router unless you have it set to Router instead of Gateway in Advanced Routing. Basic Setup should have a Connection Type of Automatic Configuration -- DHCP. I use DD-WRT, so some options may not be the same on your router.

Know the default ID and password before resetting. I think Linksys used admin/admin or {blank}/admin and DD-WRT uses root/admin.

Resetting should get you to a good starting place. You should be able to easily get connected to the internet with a wired connection quickly.

For wireless, you should just have to set it to Mixed Mode, set the SSID, and leave it Bridged. On the security tab, set the security to to the highest level the laptop will support. If it supports WPA2 (WPS2 Personal) and AES, use that on the router. You just have to make us a password of random characters like ha%jkd6( (don't use that one). Save and apply the settings. You should be able to connect to Wireless and get to the internet.

Thanks, lhollow. Yes, everything is as you say. With the addition of MAC cloning. I'll do as suggested and reset the router to factory defaults and start over.

This router I never put DD-WRT on, of that I am sure. I have a couple of others that have DD-WRT on them, but not this one. I also have a new Belkin I might just try to attach.

This entire thing is a mystery to me - but as I said, I never messed with a cable modem or Mediacom before.

While your at it, install the latest firmware. Be sure to get the right one, since there's about 10 different hardware versions (Look on the bottom of the router on the label) of the old trusty WRT54G. I have an old ver2 wrt54g and run firmware ver 4.21.1, last released 1/30/2007

Modems don't hand out IP's via DHCP unless the modem is not in block sync and it's just to maintain connectivity with the modem for diagnostic purposes.

MAC cloning has not been needed on Cable Networks for many many years.

Yes, beachintech , that's what the article that I posted above had exactly said:

quote:

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The SB5100 family of modems contain an internal DHCP server, which is active until the modem registers with the CMTS.

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Since you replied to me, I can only assume you thought I posted or understood something incorrect?

Uh, don't mean to sound simplistic....but is the wireless on the router enabled? Also, you might check that MAC filtering is turned off. I had a WRT54G that died earlier this year. If so, then it seems that the wireless is not working.

Update:

I got out to my sisters place yesterday. The job is not done, but here are the results.

- I reset the Linksys router to factory defaults, and just added in an SSID. Nothing else. Plugged it in, and initially it worked wired/wireless to my computers. Could not make a connection with my sisters Vista.

- After rebooting everything again, and setting security on it, nothing worked....even the computers that worked before. Connection to the router was OK, but no Internet. Debugging produced no "joy".

- I took a spare "new" Netgear router I had and put that on. (after properly shutting down all devices and bringing them up in the right order). Worked right out of the box. Full WEP security,and everything configured. My 3 laptops (1 XP, 2 W7) connected through the wireless and wired side fine. So big "joy" on that one. That is how I expected this "simple" job to go when I started.

- her laptop running Vista still will not connect wireless. But at least I know it is a machine-specific issue at this point. I ran out of time so am heading back there today to finish up.

- On the Linksys, security seemed to be the issue that really stopped things. But overall it was flakey. Time to reload firmware in that one.

Thank you everyone for all your suggestions. I learned something about cable modems - they do not need MAC cloning!

Final update:

everything is working fine. Her laptop just needed a little "adjusting". Took about 2 minutes with a fresh mind.

For grins, I loaded the latest firmware in the Linksys router that was not working. It seemed to fix the issue with WEP security and the Mediacom modem.

I took that same router and put it on a DSL line/modem BEFORE updating the firmware and it worked fine with WEP security. Technically, I can't come up with a scenario why it failed with the mediacom modem, but it consistently did.

Thank you all for your help.

WEP is not secure.