Proper Static IP Configuration

[JEG2]

I am still unable to reliably communicate with my ISY-99i via the Web interface. After a time, I just lose the ability to talk to it. Telnet connections are also refused, but it answers ping requests.

 

I suspect this is an issue caused by my network setup. In other words, I suspect it's my fault. I would like to try to describe my network and see if anyone has advice for how I resolve this.

 

The relevant parts of my network are that I have a cable modem, an Airport Express just behind that which all of my devices us to reach the Internet (directly or indirectly), and a second Airport Express the ISY-99i is connected to. That second Airport Express is set to "Extend a Wireless Network."

 

I've tried everything I can think of with this setup, but I just can't seem to get the ISY-99i stable. Here are some questions I have for the network gurus:

 

1. I really thought a DHCP Reservation on the main Airport Express (behind the cable modem) and just setting the ISY-99i to configure automatically from the DHCP server would work, but it doesn't seem to last. Is this because I have the second device in extend mode?

 

2. Do I want to configure automatically from DHCP server, or would it be preferable to static IP as the ISY-99i's configuration? I've tried both and haven't seem to find a winning combination. If I configure manually, which router would I call the "Gateway." The one the ISY-99i is connected to or the one behind the cable modem? Which one would it take it's DNS from (another setting)?

 

I found a post that very much describes my problem, in a different scenario:

 

http://forums.macrumors.com/showthread.php?t=539509

 

This is what led me to decide my network is the issue. It also led me to read this document from Apple:

 

http://manuals.info.apple.com/en_US/Designing_AirPort_Networks_10.5-Windows.pdf

 

That has me wondering if I need to setup a WDS as described in there, or have the second router join as a client (but then I don't know how to configure the ISY-99i).

 

As you can see, I'm a networking dummy and I'm lost. Any suggestions are appreciated.

 

Thanks.

 

James Edward Gray II

[Michel Kohanim]

Hello Mr. Gray,

 

I think the problem might be that your second airport express is also issuing its own IP addresses. So, the first thing I recommend to isolate the problem is to hook your ISY (if possible) to the first airport express. If the problem persists then we have to figure out if your cable modem also issues IP addresses and if so, we would have to disable DHCP in your first airport express.

 

In short, there should only be ONE authority for issuing IP addresses.

 

With kind regards,

Michel

[JEG2]

I don't believe the Airport Express that the ISY-99i is connected to is providing DHCP addresses. I believe extending a network disables that.

 

Sure, my cable modem assigns addresses (though mine only allows one). Don't they all? It's on the other side of the first Airport Express though, so I can't see that being the issue. Wouldn't most home networks have a similar setup?

 

However, I do have another DHCP providing device on the network. The reason is that I run two wireless networks in the house, one for /n devices and one for /b and /g devices. I guess this could be my problem. I can't lose this feature though. It's vital that I support both types of devices.

 

Wouldn't setting a static IP eliminate this issue? It seems like that would save us from the troubles of it receiving an DHCP lease, right? Most of my experiments have been done using a static IP assignment in the ISY-99i's configuration, but this is still an issue.

 

James Edward Gray II

[Michel Kohanim]

Mr. Gray,

 

Thanks so very much for the detailed reply.

 

You can surely use static IP address but the main questions are:

1. Are you certain that this IP address is NOT assigned by the DHCP servers to any other devices?

2. Is this IP address routable via all other devices?

 

With kind regards,

Michel

[apostolakisl]

However, I do have another DHCP providing device on the network. The reason is that I run two wireless networks in the house, one for /n devices and one for /b and /g devices. I guess this could be my problem. I can't lose this feature though. It's vital that I support both types of devices.

 

James Edward Gray II

 

You shouldn't have this extra level of dhcp addressing. You should shut off the dhcp server function on that unit. Don't use this router as a router, only a swtich. When using a router as just a switch, plug nothing into the WAN side, everything goes to the LAN ports (the wireless connections should automatically be "LAN")

[JEG2]

You shouldn't have this extra level of dhcp addressing. You should shut off the dhcp server function on that unit. Don't use this router as a router, only a swtich. When using a router as just a switch, plug nothing into the WAN side, everything goes to the LAN ports (the wireless connections should automatically be "LAN")

 

You are right. I have at unit, an older Airport Express, in "Bridge mode" and I just verified that shuts off DHCP. So you are right. I described it wrong.

 

This gets us back to the fact that there is only one device handing out DHCP leases to my devices.

[JEG2]

1. Are you certain that this IP address is NOT assigned by the DHCP servers to any other devices?

 

I'm sure, yes.

 

2. Is this IP address routable via all other devices?

 

Yes, they all use the same subnet mask.

 

I've verified that this problem is not related to the ISY-99i. I can reproduce it without that device, much like the forum link in my original post describes.

 

It's an issue with how I've setup the Airport routers in the network and it's totally my fault. I was just hoping I might catch a networking guru here who knew the right way to configure them.

 

I'll keep searching and experimenting and report back if I find a setup that behaves…

 

Thanks.

 

James Edward Gray II