[Wiltshire] I'm back online at last but...

[John Larkworthy]

Hi,

Just caught up with this one. We recently had our NTL Cable Modem die. Having got a replacement VM modem, the nice man in India said he had enabled the modem to communicate but I could not get access through to Google as a tes while pretending to be running XP.. The most recent computer we have is an Acer Aspire One running Linux and this would not connect even when directly connected to the modem. I gave up and decided to research the issue myself. 

I had a look on the net and found someone with an XBox having similar problems.  I connect to the Modem via a cheap router to share the connections. It seems Simon is correct - its all about getting the DHCP/ARP mappings correct. I noticed that if I power the Modem on after the router the WAN IP is 192.168... which is clearly not routable and the lease is for about 30 seconds. So from our friend with the Xbox which seems to work is:
Power everything off. 
Power on the modem and wait for it to settle by watching the lights.
Power on the router and wait.
Finally power on the computer and get a lease to the router/gateway.
Check router has a routable WAN lease through to the Internet.

This switch on process should ensure each step only gets the lease it needs and none of the temporary engineering leases. As a result of powering everything on and off in the correct sequence I did not need to call VM support to resolve the issue.

<Engineering hat>
Allowing the modem to settle prevents it from issuing an engineering IP address from it's internal DHCP server. This server is only active for the first 60 seconds after power on so that when the router is turned on later, the DHCP request is forwarded through to the VM DHCP server and a dynamic IP address is aquired by the router. 
Turning the computer on later allows this to get it's IP address from the DHCP server in the router.
</Engineering hat>

regards,

John.



----- Original Message ----
From: David Fletcher <dave at thefletchers.net>
To: wiltshire at mailman.lug.org.uk
Sent: Wednesday, 17 December, 2008 23:13:28
Subject: Re: [Wiltshire] I'm back online at last but...

On Wednesday 17 December 2008 20:26:36 Dianne wrote:
> Thanks for all the help I've been given.
>
> I finally put in a spare hdd, installed XP, whinged at Virgin, who told
> me to power off modem, plug ethernet back in, etc etc - exactly what
> i've been doing for 6 weeks, and the darn thing worked! Repartitioned
> and installed 8.10 clean, and it worked.
>
> XP wouldn't let me use my old user name, so in a fit of childish pique I
> chose "linuxrules" as my user name. :)
>

Do you now have a router in between the Virgin Media cable modem and your PCs? 
It provides you with some safety and local stability.

Dave


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