Migrating to new modem router, with both old and new active during the migration

[squeakoz]

I currently have a home LAN using a DGND3300v2 ADSL modem router, secured by WEP and MAC address and tying down the number of open ports. I did this because at the time, I had some devices which didn't support WPA-anything. One of the downsides (apart from the weaker security) is that I can't use WPS. I would like to migrate to a new modem router which will support VDSL, and much else besides. I see my way forward as being to install the new modem router secured by WPA2-PSK and moving everything to it which will support that encryption method. Now because I am connecting to ADSL, and my ISP requires me to login, I am wondering what the is the best way of connecting two modem routers to my ADSL line. I am guessing that one router will be the master, and will connect to the ADSL service, and the second one will connect over IP to the first router, or is there a better way?. How do I tell the second router that it has no ADSL service, just IP like a standalone router? Eventually my remaining devices which only support WEP will disappear, and I can go back to one.

Are there any gotchas with this logic? There must a body of knowledge somewhere covering migrating progressively from one modem router to a new one.

[antinode]

> I am guessing that one router will be the master, and will connect to
> the ADSL service, and the second one will connect over IP to the first
> router, or is there a better way?

   That's the way.

> How do I tell the second router that it has no ADSL service, just IP
> like a standalone router?

   You may want to configure the old DGND3300v2 as a wireless access
point.  Its manuals (or some other Netgear docs) may explain how to do
that.  Generally, I'd guess that you want to disable the DHCP server on
the DGND3300v2, and assign some convenient address to its LAN interface
which would be consistent with the new (used-as-router) router.  I don't
see a WAN Ethernet port on the DGND3300v2, so I'd guess that you'd
connect one of its LAN ports to a LAN port on the new router.

   The DSL/phone port on the old DGND3300v2 would be left unconnected.

[michaelkenward]

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@squeakoz wrote:
There must a body of knowledge somewhere covering migrating progressively from one modem router to a new one.

---

Recycling a modem and turning it into a router, wifi access point or something else is a regular topic. (Not sure if that is what you have in mind from your message.) It really doesn't depend on the modem, or even the make, so a generic Google/Bing search might find more advice, something like "use modem as a router".

One word of caution on reusing the DGND3300v2 for anything permanent, it has 100BASE LAN ports. This means that it is slower than some modern Internet services and will not get the best out of newer 1000BASE hardware.

To be honest, in the scenario you describe, I'd make notes of the important settings (Alt+Print Screen grabs are a great help.), then I'd simply swap out the old modem/router for a new one. You may be lucky in that the setup wizard for the new device is compatible with your Internet service, resulting in a fairly painless process. In the long run, it might take just as long to do all that manual stuff as it would be to recreate from scratch.

You might get more detailed advice if decided which modem/router you fancy and asking about that.

[squeakoz]

Thanks. Ive got screenshots of the config screens, it's part of my backup ritual. But the fundamental reason for the question was that I want to have both routers (well, both wifi radios) active during the transition, so I can take my time getting the hang of the new router and migrate the various devices (that support it) across to WPA2 then see what's left. so the SSID running WEP would run out of the old router, and a new SSID with WPA2 would run out of the new. I was just a bit uncertain how the traffic would flow from the devices on the WEP network through the new router and out to the internet.

[squeakoz]

Why would I need to disable DHCP on the old router? I figure I would turn off NAT on it, but I would have thought that having a range of addresses which doesn't overlap with the range managed by DHCP on the new router would work. 

[michaelkenward]

Some modems make it easier to turn them into routers and access points than others. For example, newer models come with a WAN/Internet socket on the back. In that case, use that and you bypass the modem.

In your case, it sounds like you want to use the old modem as a wifi access point. There's a bit in the manual about "Wireless repeating".

You'd have to disable DHCP on the old modem and check that it doesn't clash with other IP addresses. Then plug the DGND3300v2's LAN socket ino the new modem's LAN socket.

Again, I'd do a generic search, this time try "modem as wifi access point", "use adsl modem as wifi access point" or something similar. Unless one of the resident geniuses knows the ropes.

[michaelkenward]

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@squeakoz wrote:

Why would I need to disable DHCP on the old router?

---

Because just about everyone advises doing so in these circumstances.

Doubtless you could try any number of options, but for an easy life when you don't plan to make this a permanent feature seems a bit perverse and asking for trouble. But it is your call. If it doesn't work, you can always resort to plan B.

[antinode]

> I figure I would turn off NAT on it, [...]

   If you're not using the DSL/WAN interface, then it shouldn't ever
_want_ to do any NAT, so no action required on that front.

> [...] I would have thought that having a range of addresses which
> doesn't overlap with the range managed by DHCP on the new router would
> work.

   Or, you could do that.  Perhaps.  With one DHCP server, conflict is
impossible; with two, you need to be careful.  Your choice.  But I don't
think that there'd be anything to stop any client anywhere from getting
DHCP info from either DHCP server, so it's not as if you could be sure
that only the WEP-using devices would get their info from the
DGND3300v2's DHCP server.  More important, the idea of an access point
is that it acts more like a network switch, less like a router.  The
new/main router is the gateway to the outside world, and would have the
DNS server/relay, while the DGND3300v2 wouldn't know squat, so I'd
expect its DHCP server to be too ignorant to be useful.

[squeakoz]

Yep, thats a fair point.