Trying to use Vonage RT31P2 as switch

Posts: 3 · New Forum Member Joined: Feb 09, 2009 Posts: 3

Here is my connection setup:

Internal Addresses:
DLink 4500 - 192.168.0.1
Vonage RT31P2 - 192.168.0.2
Airport Extreme - 192.168.0.60
Airport Express - 192.168.0.70

I need to have the DGL-4500 plugged into the DSL modem (as per ISP) so I cannot plug in the Vonage router directly to the Wireless.

Speedstream DSL <---- D-LINK 4500 (WAN Port)

D-Link 4500: Ethernet 1<--- Network Printer
Ethernet 2<--- Airport Express (to extend wireless)
Ethernet 3<--- Gaming Computer
Ethernet 4<--- Vonage RT312P2

Airport Extreme: Ethernet 1<--- PS3
Ethernet 2<--- Wii
Ethernet 3<--- NAS device

Vonage RT312P2: WAN Port <--- DLink DGL-4500
Ethernet 1 <---- Work laptop

Here is the interesting part. The Airport Express (which is about 200ft from the DLink, does allow internet connections. I use the PS3 for online gaming all the time. The NAS device is setup for only internal access, and the Wii goes on the Internet. That rules out the DLink as a culprit.

I do get telephone signal (in fact I have Vonage hardwired throughout the house). What I can't do though, is use the Vonage as a switch to connect to the internet. I have DHCP setup on all devices, all in the 192.168.1.x subnet.

DHCP particulars
DLink - 192.168.0.10-100
Airport - 192.168.0.101-254
Vonage - 192.168.0.3-9

Whenever I plug my work laptop into the Vonage router (no room left on the DLink), I get an IP address of 192.168.0.4 with gateway of 192.168.0.2. It just will not connect outside of that. I can ping the Vonage router, but nothing else. Obviously internet does not work.

Check picture for details.

[img]http://img98.imageshack.us/my.php?image=homenetworkmg9.jpg[/img]

Posts: 656 · Posted: Mon Feb 09, 2009 8:02 pm Post subject:

I think I see part of the problem. Networking equipment has issues when you try to assign the same 24 bit subnets behind multiple routers when static routes are not used. The reason is because a subnet is used to determine who is on your LAN. Meaning anything connected to the local switch. Since your using a Layer 3 router, when trying to ping another 192.168.0.x address not on your switch, the packet will not be forwarded to the Default GW. It will stay on the switch but since there is no IP on the switch to match your request, it dies.

This is evident in your Ping. From the Laptop you can ping 192.168.0.2 but not anything else like 192.168.0.20. This is because 255.255.255.0 (24 bit subnet) tells the packet not to go to the default GW(192.168.0.15). In order for a packet to go to the default GW since it thinks it is on your LAN, it would have to be on a separate subnet.

Your data also does not match your diagram so your going to have to be a bit more clear.

In your diagram, your showing the WAN IP on the RT31P2 is 192.168.0.15 and the LAN IP is 192.168.0.2 however in your post you state the following "What I can't do though, is use the Vonage as a switch to connect to the internet. I have DHCP setup on all devices, all in the 192.168.1.x subnet".

I suggest you make a simple change to your LAN IP on the RT31P2. Make is 192.168.1.1 or 1.2 and then release and renew the IP on your Laptop and ensure it gets a 192.168.1.x address. Then retest internet. This puts you on a separate subnet. While you should have internet, when doing this, it will make it difficult to access machines behind other NAT's. In this case, a simple 8 or 16 port switch off the DGL-4500 would make the most sense so that each device is on the same subnet and accessible to one another. Otherwise your going to have to set up static routes on each router (not the DGL-4500) to tell client requests how to get to the other network.

I hope this makes sense. It's hard to explain this but it is very simple. I am not the best at trying to simplify explanations.

Posts: 3 · New Forum Member Joined: Feb 09, 2009 Posts: 3

Your explanation makes perfect sense, and I should have thought of that myself. Sometimes you need to bang out against another head to see the obvious, or in my case, have it shown to me. I will give that a go later on and post here the results. The Airport Extreme must be defaulting to a switch in this configuration... it is hard to tell, since the software for the Extreme is so very basic.

I am really loathe to have yet another piece of hardware that takes a power port in my office. With 2 computers, cell phone, printer, router, recording gear, etc. I have run out of power ports to plug stuff into, and the last thing I want is another switch.. but then a simple Layer 2 switch should do exactly what I want it to do. Since I need to plug in my work laptop to get on the Internet (and hence VPN) I also want it to have access to my Network Printer which would remain on the 192.168.0.x subnet...

Thanks for the help!

Posts: 3 · New Forum Member Joined: Feb 09, 2009 Posts: 3

Thanks for the help. That worked for me perfectly, and when I say perfectly, I mean I can also print on the 192.168.1.x subnet. Obviously it works just as well as an internal router as it would as an external router.

I cannot believe that I did not think of that myself..... but I suppose I am a long ways from my own CCNP days!