Weird DHCP assignment problem CISCO EPC2425

the_duduman

I am having major problems getting my network to work properly and am going crazy trying to fix it. Can someone maybe help me out? I've scanned through most of the numerous pages but haven't found anyone with this particular problem:

My setup is the following:

I've got a Cisco EPC2425 Eurodocsis Cable Router [CABLE ROUTER], provided by my ISP (UPC) and it's connected to the main cable splitter (provided by UPC), DHCP enabled and serving 192.168.1.x addresses.

Downstream is a Cisco E4200 Wireless Router [PERSONAL ROUTER] (w. 4 port switch and wireless) now configured to serve 192.168.0.x adresses.

The problem is when I connect my PC to the PERSONAL ROUTER it gets a 192.168.100.x adress (!!!!).

If I browse to the gateway 192.168.100.1 I get the following pages...





I am at a loss as to what this is? Is it an upstream UPC device - since it has a lot of "analogue signal metrics" stuff on it? It definately is not a physical device in my house, as said the main TV cable "splitted" output goes into my CABLE ROUTER, no other devices in my house. Or could it be that the 2425 used to be Thompson and this is some legacy management page?

Needless to say the UPC helpdesk couldn't help. After waiting an hour to get through to the call centre they gave me the standard advice: to disconnect my router for 1 minute (of course they won't wait for reboot) and then call back...when I did they allowed me to send them a mail, which hasn't been answered to date.

So my question is: anybody got a clue as to what's going on? Why don't the CABLE and PERSONAL ROUTER not respond to the DHCP lease request and some upstream device in the ..100.x range does? Is it a timing thing? Could I block the DHCP request from going upstream? So beyond my subnet? An why is this Thompson thing be serving DHCP to begin with?

I am able to connect to the Internet if I connect to the Cable Router directly using its Wifi and DHCP. I've also been able to connect to the internet via my PERSONAL router, using static ip adresses, but this is only temporary, after a while the connection goes down.

Any help is greatly appreciated!

the_duduman

Hmmm...see the images didn't get posted:

http://www.freeimagehosting.net/3f4c8

http://www.freeimagehosting.net/26c3f

demanufactured

Funnily enough if i browse to 192.168.100.1 it brings me to the admin page of MY thomson router , Even though that is not my gateway adddess (mine is 10.1.1.x)

very strange , and there isnt many menus on the page YOU are getting

Might be a device upstream of you , hard to say...can you do a trace route to it??

the_duduman

Yes it is strange...it's driving me nuts, especially since the helpdesk people just don't seem to know the first thing about anything...

Tracert gives me 1 hop to... indeed to this Thompson cable thing that's apparently dishing out IPs... instead of any of my two routers...

Again note that I have a Cisco Router, with Cisco branding, nothing Thompson! like this: http://www.freeimagehosting.net/b1711

I can fix it temporarily with Fixed IPs but it's intermittent...will bog down every 5 minutes...

dunworth1

thats very interesting maybe DingDong might be able to shed some light on this

bealtine

192.168.100.1 is part of the standard for DOCSIS and is an alternate address for your modem.

No mystery there.

the_duduman

Problem solved!

Called UPC today and guess that monday morning is the best time to do it. Got through straight away and they sent someone by in the afternoon to replace my modem with the latest 3.0 version (way to go UPC!). But after replacement the problem still remained - initially puzzling the cable guy as well...but he identified the problem:

Turns out the problem came through the "ethernet cable" input on the UPC media box (the one connected to my TV) which I had connected to a switch hanging from my personal router. I assumed this was used to get TV program data or whatever and basically since it was there connected it. But it's used only for diagnostics and yes, serves DHCP! So simply disconnecting it solved it. I definately would not have guessed this by myself.

So since I said some not-so-nice things about UPC, here goes:

You did a great job! Thanks!!!

@bealtine: sorry, that wasn't it in this case.

bealtine

the_duduman wrote: »

Problem solved!



@bealtine: sorry, that wasn't it in this case.

Fair enough....glad you got it sorted.

192.168.100.1 is the address of the modem in any case just try it:)