Different IP in two PC's using single router

[jcarle]

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

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

[GrofLuigi]

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

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

[kumarkumar]

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)

Edited September 3, 2008 by kumarkumar

[Mr Snrub]

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

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.