Shopping Product Reviews

Virgin Media – Forcing to change sticky IP

Virgin Media is a leading broadband provider to the UK consumer and commercial markets. In fact, at the time of writing, Virgin Media was second only to British Telecom (BT), the biggest player.

As an Internet Service Provider (ISP), Virgin Media makes it easy to assign dynamic Internet Protocol (IP) addresses to routers on your network. These routers are usually the Super Hubs supplied by Virgin Media. A Super Hub is a combination of a modem with built-in wired and wireless routers.

Dynamic IP addresses are assigned on wide area networks (WANs) using Dynamic Host Configuration Protocol (DHCP) servers. At the router level, the router can translate this WAN IP into many local area network (LAN) IPs in a process called Network Address Translation (NAT). These LAN IPs are generated on demand for network equipment such as computers as they connect to the router via cable or wirelessly.

Dynamic IP typically comes with a seven-day lease period. In theory, when the IP lease expires, a new IP should be assigned to the router. However, in reality, the router “renews” its assigned IP in the middle of its lease and is assigned the same IP address.

If you want to change the dynamic WAN IP assigned to your router, you just need to turn off your router for at least fifteen minutes and then turn it back on, and that would normally be enough. However, with Virgin Media Super Hub, this does not normally work as I discovered myself.

ISPs prefer to give dynamic IP addresses over static IPs only because dynamic IPs represent minimal administrative overhead which is important to keep costs down. Additionally, as today’s IPv4 addresses are becoming increasingly rare due to the continual explosion of new networking places connecting, dynamic IPs allow for IP “recycling”. This is the process where IP addresses are sent to a “pool” of IP addresses when routers are offline, allowing published IP addresses to be taken and used by those that connect.

Sometimes, even if the router goes offline or the IP address lease time to the router expires, the same IP address from the “pool” of IP addresses could be assigned to the router. In such circumstances, the dynamic IP address behaves more like a static IP address and is said to be “sticky”.

Other times you may also be assigned a “duff” IP address, that is, an IP address that is “corrupted” in some way, as happened to me recently. Despite several attempts to restart the Super Hub, I kept getting the same dynamic “group” address. This situation was completely unsatisfactory for me as the IP address prevented me from accessing my own external sites! The solution I read about mentioned changing the Media Access Control (MAC) address of the receiving ethernet card, which in my case was that of the Super Hub.

Unfortunately, the Super Hub does not have an option to “clone” MAC addresses, that is, it does not provide an interface where the MAC address of a computer on your network can be placed, which would force the current IP to be changed. The only way to present a different MAC address to DHCP servers would be to attach an external Internet Network Card (NIC) to the Super Hub. In other words, make the Super Hub just a modem and connect an external router. Fortunately, the Super Hub you provided, Netgear’s VMDG480, allowed the Super Hub to switch to modem-only mode.

Fortunately, I also had a replacement router, the excellent ADSL 2/2 + Vigor 2820 Series security firewall with the latest firmware, version 3.3.5.2_232201. Although it is an excellent modem / router in its own right, the type of router is not important to the problem we are trying to solve here.

I followed these quick and simple steps below to get everything working.

1. In the Super Hub user interface, enable modem mode.

2. Connect the Ethernet cable from the specified port on the Super Hub to the WAN 2 port on the router.

3. In the router’s Control Panel, make sure Physical Mode is set to Ethernet.

4. On the WAN 2 interface, the IP address, subnet mask, and IP address of the gateway should be obtained automatically from the modem.

5. Leave the MAC address as the default.

6. For future problems with a duff IP, I have the option to clone a MAC address which should force a replacement of the WAN IP.

And this solved the sticky intellectual property problem with Virgin Media. Fortunately, the new IP address was “clean” and allowed me to access the sites that could not be reached with the old corrupted IP address.

Good luck!

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