I have two PC's connected using DLink DI-514 wireless router. Currently both the PC's are Wired.
The router in turn is connected to the Cable Modem.

Cable Modem --> DLink DI-514 --> PC1 , PC2 (same IP in PC1, PC2)

But I get the same IP address in both the PC's. How can I configure the router to give different IP's to the two PC's.

[I have another Allied Telesis (AT-FS705LE) Ethernet switch. If I connect that in place of the DLink DI-514, I get different IP in the two PC's.

Cable Modem --> Allied Telesis (AT-FS705LE) --> PC1 , PC2 (different IP in PC1, PC2) ]

All the settings in DLink DI-514 are here http://support.dlink.com/emulators/di514_revb/h_wizard.html

I think it's a NAT router that doesn't support more than 1 public IP address - I couldn't see a way to even disable NAT, though I only went through the emulator briefly.

If the switch is behind the cable modem and the clients are connected to that and get unique public IP addresses, what purpose does the router provide?
(Typically home broadband routers allow multiple clients to access the Internet when only 1 public IP is available.)

Basically I look at the router as well as the ethernet switch as a internet connection splitter (in layman terms).
The Cable Modem has only one ethernet outlet. So to connect the two PCs I initially used the ethernet switch. This gave me different IP in the two PC's (I am not sure how). I need different IP in the two PCs for a specific reason.

Few days back I had to give the ethernet switch to a friend. I had the Dlink router at home. So I connected that in place of the router. Unfortunately now I get the same IP in both the PC's

I'm not familiar with this particular model, but I recognize most of the staff.

1. If everything was OK, it shouldn't do what you described, so something is wrong. But you knew that already.

2. You can set the two computers to have their own static addresses and not bother with anything DHCP. If it's a normal router, it should accept them.

3. If you want to have DHCP and can't fix 1., go to "DHCP" button on the first page and set the "Static DHCP" area according to MAC addresses of the computers (for all they care, it's still dynamic).

4. For troubleshooting 1., check if everything on the "DHCP" page, upper part (DHCP Server), is as in the example. Check if, on your computers, in network connections/properties everything is set to "automatic".

5. I see Mr Snrub replied in the meantime. As I said, I'm not familiar with that model and it's possible it to work in different way than normal routers and/or have some features disabled.

GL

When you switched them, did you renew the network connection on the PC's (right click -> repair)? You may also try:

ipconfig /release
ipconfig /renew

but it might be risky if anything is wrong with the PCs (it may break them even further).

GL

I think public address is not important - It has LAN settings and DHCP settings. If it has multiple LAN connectors (plugs), it should be able to do the job.


NAT takes care of that (and they get unique LAN addresses). From the info provided, I think that the problem is on the LAN side. If the router isn't indeed crippled (I've seen some crippled that ISPs give).

GL

It depends on whether the clients were getting public or private IPs directly from the cable modem, and what they get now - if it was an IP conflict I would expect only 1 of the 2 clients to even work, which is why I assumed the OP was talking about public IPs.

If the cable modem and both clients are connected to LAN ports, it should act as a switch as before - does that help?
That would make the network infrastructure identical as to how it was with the switch in place of the router (with the addition of wireless clients), so should resolve your problem.

Oh yeah, but that's an unusual setup. It didn't even cross my mind - I don't know if it is possible? Wouldn't the router 'object' to being demoted to a switch (not expect to work that way/not be wired to work that way/not be configured to work that way)?

If it works, that would explain why there is only one IP address... Phew, I'm slow, but I'm catching up.

It's now up to the original poster to tell us where are the wires plugged in.

GL

* Edit : but something is still wrong - as the OP said (and I had that setup once), cable modem with a switch worked correctly - it gave different IP addresses (has own DHCP server).

Consumer routers are often just a router with an integrated switch. Depending on the internal mechanics of this particular model, he may be able to simply plug in the modem to port 1 and the PCs into port 2 and 3 and it may very well act like a regular switch without NAT if he turns off DHCP. It's a stretch, but it may just work.

Correction...

There are five ethernet outputs on the DI-514. One WAN port and four non-WAN ports



I tried connecting the ethernet cable from "Cable Modem" to the DI-514 router at
1) WAN port --> same IP in the two PCs
2) One of the other four ports --> different IP in the two PCs

The two PC's are always connected to two of the four non-WAN ports.

Can I someway have different IPs with case #1? It would help me connect another Laptop and at the same time have different IPs in all machines.

That would be the integrated switch I was talking about.

Nope, this is the scenario I first described, a home broadband NAT router is designed to have 1 public IP address and assign individual private IP addresses for the internal clients - the traffic from all clients on the Internet is seen to come from the 1 IP address.

Different IPs as seen from the computers or as seen from the Internet? All the time, I assumed you were talking about #1 (as seen from the computers).

Wow, I finally caught up.

GL

Different IPs as seen by the internet (outside world).

One more thing. I can know the IP of the machines as seen by the internet only by going to websites like whatismyip.com, displayip.net, etc. I thought "ipconfig /all" gives all the info about IP address. Why is it different?

Then it's cable modem + switch you need, as others said.


Because of the cable modem. It also has two interfaces (outside address and inside address(es)). Or something like that.

GL

I have yet to see a cable modem that does NAT, so this is highly unlikely.

Correct again. I don't know what I was thinking when I wrote that... I was lead on by kumarkumar's post and thought it was normal. Of course they should show as different in ipconfig (if set up as cable modem + switch).

kumarkumar, you have some unusual setup there

GL

Let me give some more info that happens in my case. Is it normal?

1) Using Cable Modem+DI-514 Router

Case I - DI-514 Router as a Switch
(i) IP as seen from websites such as displayip.net --> Different IP in both PCs (IPAddress 1, IPAddress 2)
(ii) IP as seen from ipconfig /all - Different IP in both PCs (IPAddress 1, IPAddress 2)

Case II - DI-514 Router as Router
(i) IP as seen from websites such as displayip.net --> Same IP in both PCs (IPAddress 1)
(ii) IP as seen from ipconfig /all --> Different IP in both PCs (IPAddress 2, IPAddress 3)

2) Using Cable Modem+Applied Telesyn AT-FS705LE Ethernet Switch

(i) IP as seen from websites such as displayip.net --> Different IP in both PCs (IPAddress 1, IPAddress 2)
(ii) IP as seen from ipconfig /all --> Different IP in both PCs (IPAddress 1, IPAddress 2)

Perfectly normal - same kind of setup I have here.

The cable modem forwards the DHCP requests to acquire public IP addresses, so clients that are connected to a SWITCH will get unique public IPs (I have up to 5 through my ISP).

When a ROUTER is used, it will obtain 1 public IP address for its WAN interface, and act as a DHCP server for the internal clients who will get unique private IP addresses - from the Internet these clients would all appear to be behind the same public IP address.

When the cable modem is connected to a LAN port on the router, the routing logic is not being used - the device is being used as a switch, same as in the first scenario above.


My network as it stands today:

The clients and server are all behind the DIR-655 router, so only 1 of my 5 public IP addresses is used.
If I needed to use a different public IP address, I can connect a client to the DES-1005D switch - but I don't like to connect clients or server to dirty networks.

There isn't really much that requires clients to have unique public IP addresses, if a UPnP router is used.