RT31P2 - How to get a static IP address on LAN

I have the following configuration:

Cable Linksys DLink Wireless Modem ------ RT31P2 -------- DI-604 -------- Router ------- PCs NAT & DHCP Router | no NAT | no DHCP | |---- Desktop PC

I'd like to configure the Desktop PC as an FTP server and I have setup port-forwarding on the RT31P2 and the DI-604 routers. It works except that the DI-604 sometimes gets another IP address from the RT31P2 and causes the port-forwarding to no longer work because the IP address of the downstream router has changed.

The RT31P2 sits in front of the DI-604 because the RT31P2 is for voip service and it gives voice traffic priority over other traffic (QoS).

The DI-604 has a static DHCP function that allows me to tie the Desktop PC to a specific address on the DI-604. The static DHCP keeps the Desktop IP address constant.

Is there a way to keep accomplish this?

It would be great if the RT31P2 had static DHCP - perhaps there's another way to accomplish the same function.

Can I configure the DI-604 to have a static address and turn off DHCP/NAT on the RT31P2? A static WAN address on the DI-604 requires I define also DNS server addresses and I'd like to keep getting those automatically.

Any other suggestions?

Chris cjtwantstoknow

Reply to
cjtwantstoknow
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This is the first time I've ever seen anyone try to use *THREE* routers in series. Is there some reason you think you need the extra two routers? The RT31P2 is an ethernet router with all the features that the other two routers duplicate (except wireless).

Start by removing the DI-604. It does nothing useful.

Then, reconfigure the Wireless Router (no model number specified) into an access point. Do not connect anything to the WAN port. Setup the IP address to be in the same /24 group as the RT31P2 but on a non-duplicated IP address. Disable the DHCP server. Now, it's just an access point.

Plug the PC's and Desktop PC into the RT31P2 LAN ports.

Well, if you insist on using the DI-604, dive into the RT31P2 and see if it has a feature called "static DHCP". If so, configure it to give the MAC address of the DI-604 router always the same IP address. I couldn't find anything in the manual at: ftp://ftp.linksys.com/pdf/rt31p2_ug.pdf that would indicate that it has this feature. The only alternative is to assign a static IP address on your desktop PC that's acting as an FTP server, and port forward the RT31P2 to point to this static IP address. Please pick an IP address that is NOT inside the DHCP assigned IP address range of the RT31P2.

Yes, the RT31P2 *MAY* be installed in front of an existing router. However, there's no reason why it must be installed in front of this router. The recommended setup in the manual does not show the extra router. The RT31P2 duplicates all the functions of the DI-604 with the added complexity of dealing with two routers. There's no need to do that. Just use the RT31P2 and sell the DI-604.

Reply to
Jeff Liebermann

Jeff,

Thanks for your advice!

I use the DI-604 because it gives me the ability to assign an IP address to a MAC address in the static dhcp setup. Since I share the wireless network with others, it allows me to assign specific IP addresses that in turn can be specified in the firewalls on my PCs. This keeps my neighbors out of my PCs and me out of theirs. I like to keep the desktop and the wireless clients on the same network/router because then I don't have to deal with port-forwarding to support Microsoft file sharing.

The RT31P2 doesn't support static dhcp so that's why I don't use it instead of the DI-604. As far as the wireless device goes, it's there because it is physically situated away from everything else and using its LAN ports is not possible. The desktop needs to be wired because certain applications require a network card and don't work with wireless cards.

I'll probably end up plugging the desktop (the FTP server) into the RT31P2 and assign it a fixed IP address.

BTW - The wireless device is a Parkervision WR1500.

Chris

cjtwantstoknow

Reply to
cjtwantstoknow

Reply to
Jorge Padrone

Well, I guess that's one way of doing it.

Well, that will work, but if you want to preserve your existing setup and make it easy to get to your desktop PC from other machines, all you need to do is assign a static IP address to the DI-604 *WAN* port. I think the RT31P2 is 192.168.15.1. Use something like: IP 192.168.15.15 GW 192.168.15.1 NM 255.255.255.0 DNS 192.168.15.1 Then, port forward 20 and 21 (ftp) on the RT31P2 to 192.168.15.15 and again in the DLink DI-604 to the IP address of the ftp server.

Thanks.

Reply to
Jeff Liebermann

There's no such thing as static DHCP, you can create a reservation but then there's no point using DHCP in that case for one machine.

Why not just leave the Dlink out completely, it serves no purpose and just configure a DHCP scope for the required number of PC's and then give the desktop a static IP address that does not exist in the DHCP scope?

David.

Reply to
David Taylor

You can absolutely use DHCP to manage static addresses.

Yeah, that was my question too.

miguel

Reply to
Miguel Cruz

Only if they're cooperative. It's easy enough for them to clone a MAC once a "trusted" machine is turned off.

miguel

Reply to
Miguel Cruz

Like several have said, there's no need to use DHCP and then defeat it by reserving an address to a machine like you are doing. Just assign a static IP address to the box but use one outside of the DHCP range.

That would still be the case.

So configure a static IP address, job done.

Jeff said use a switch, that'll work just fine.

Best solution.

Reply to
David Taylor

I am fully aware of reservations! My point here is that the definition of DHCP is Dynamic and there's no such thing as Static Dynamic any more than there's hot/cold or up/down at the same time it is not possible to have opposites like this, a DHCP reservation is a DHCP reservation but you cannot manage a clients static address, only hand out the same dynamically assigned reserved address by a DHCPOffer upon the DHCPRequest or DHCPRenew packets. Yes, i'm being picky! :)

This is unfortunate blatant abuse of terminology, I'll blame Linksys and Dlink for this at this time.

It's rather pointless setting up DHCP to manage one machine as a static address, that's more work than is required.

David.

Reply to
David Taylor

or change their IP addresses

Reply to
David Taylor

Thanks Jeff!

I didn't realize that I can specify the router as the DNS server. I guess the RT31P2 just forwards the request.

I assigned a static address to the DI-604 (outside dhcp range) and it works as desired.

I realize that I have more devices than needed. Perhaps I'll eliminate the DI-604 and assign my machines to fixed IP addresses instead.

Chris

Reply to
cjtwantstoknow

Can you get enough to make it worthwhile? They're pretty cheap.

Reply to
Derek Broughton

Correct.

Sell the DI-604 on ebay ;)

Reply to
David Taylor

They are cheap but it's redundant right now so might as well make a few pennies. :)

Reply to
David Taylor

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