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Ignitionnet · 27-10-2009, 18:15

I have my doubts that Virgin are giving leases lasting 3 minutes or 12 minutes. The shortest possible lease on the network which was as far as I know for pre-registration modems only, is 24 hours. You are losing sync due to RF issues.

Your PCs losing their IP addresses will not cause the modem to go offline. The modem is not the device handing out IP addresses and if the PCs are claiming to have lost their lease from the modem they are wrong, the modem is not visible and the IP lease should be sourced from the DHCP server not the modem. It is impossible for the modem to give a public IP address lease.

Of course, if your devices think they are losing lease from the modem, where do you think they are going when they try to renew it. No wonder it's failing if they are harassing the modem to renew a lease it never supplied in the first place, they should be request the renew from VM's DHCP servers.

If you have a PC directly connected to the modem and you do an ipconfig /all it should show a VM DHCP server, if it's showing 192.168.100.1 this is the modem and is wrong. The modem's IP address is for management or when it loses sync in which case it may give an IP address to devices behind it which is probably what happens from time to time.

The above scenario would also explain why a modem reboot is required. Until ethernet goes down for a while your kit keeps harassing whatever it can find for an IP address.

EDIT: You've been in IT for 12 years apparently, if you haven't just spent a decade plugging DIMMs and cards in you should be good to get Wireshark running on a PC connected directly to a modem and capture some traces of the DHCP transactions.

27-10-2009, 18:15	#64
Ignitionnet Inactive Join Date: Jun 2008 Location: Leeds, West Yorkshire Age: 47 Posts: 13,995	Re: What else could it be? I have my doubts that Virgin are giving leases lasting 3 minutes or 12 minutes. The shortest possible lease on the network which was as far as I know for pre-registration modems only, is 24 hours. You are losing sync due to RF issues. Your PCs losing their IP addresses will not cause the modem to go offline. The modem is not the device handing out IP addresses and if the PCs are claiming to have lost their lease from the modem they are wrong, the modem is not visible and the IP lease should be sourced from the DHCP server not the modem. It is impossible for the modem to give a public IP address lease. Of course, if your devices think they are losing lease from the modem, where do you think they are going when they try to renew it. No wonder it's failing if they are harassing the modem to renew a lease it never supplied in the first place, they should be request the renew from VM's DHCP servers. If you have a PC directly connected to the modem and you do an ipconfig /all it should show a VM DHCP server, if it's showing 192.168.100.1 this is the modem and is wrong. The modem's IP address is for management or when it loses sync in which case it may give an IP address to devices behind it which is probably what happens from time to time. The above scenario would also explain why a modem reboot is required. Until ethernet goes down for a while your kit keeps harassing whatever it can find for an IP address. EDIT: You've been in IT for 12 years apparently, if you haven't just spent a decade plugging DIMMs and cards in you should be good to get Wireshark running on a PC connected directly to a modem and capture some traces of the DHCP transactions.