Networking experts: Why won't this device pull an IP address?
February 21, 2015 7:51 AM   Subscribe

I'm following-up on this question that I posted in December. I now have two iHome iW2 AirPlay speakers that I want to use at work. The problem is that when I connect them to the LAN, they don't pull an IP address.

The speakers work fine when I use them with a consumer-grade wireless router. They get IP addresses whether I connect them with a wired connection or join them to the wireless network. But it's a different story when I try to use the speakers at work. They can't seem to get an IP address from the DHCP server on our domain controller (running Windows Server 2012). I've tried wiring-in the speakers directly to a data port, and I've tried connecting them to a wireless access point. Nothing happens – no IP address is assigned.

This is the first time I've encountered this problem. There is no security feature on the LAN that should prevent a device from being assigned a dynamic IP. Everything else I've ever connected – laptops, printers, wireless access points, HVAC controllers, etc. – has pulled an IP with no problem. Why not the iW2 speakers?

I spoke with tech support at iHome yesterday. They were not helpful in the least. The technician just kept telling me that the speakers are not intended for enterprise environments, but he wouldn't (or couldn't) address the specific issue I was raising. I asked for a different technician, but they told me that he was the only one assigned to that device.

Any insights about this? I hope I can somehow still get the speakers to work, as they'd be very convenient for the intended use.
posted by alex1965 to Computers & Internet (13 answers total) 1 user marked this as a favorite
Did you actually end up buying twenty of them as in the previous question and none of them work?

Just to try the obvious, the DHCP server wouldn't have run out of address space in the range it's assigning or anything like that? And it's not something like an IPv4 versus IPv6 mismatch?
posted by XMLicious at 8:01 AM on February 21, 2015

Response by poster: No, I bought two of them to test. The DHCP server definitely has addresses available in the pool. An IPv4 vs. 6 mismatch seems unlikely, though I'm not quite sure how I would test for that.
posted by alex1965 at 8:05 AM on February 21, 2015

I've tried wiring-in the speakers directly to a data port, and I've tried connecting them to a wireless access point. Nothing happens – no IP address is assigned.
The authoritative way is to sniff the connections and watch the BOOTP/DHCP request/response. That will show the problem, or eliminate possibilities.

I'd check the DHCP server logs, then the AP/switch configuration.

How are you verifying that the speakers don't have an IP address?
posted by graftole at 8:27 AM on February 21, 2015

Response by poster: graftole: Would Wireshark be the tool for sniffing the connection? I haven't used it before, but this might be the perfect opportunity to learn it.

The speakers can be directly connected (via a USB cable) to an iPhone. There is an iHome app that tells you some information about the status of the speaker and also allows you to join it to a specific wireless network.
posted by alex1965 at 8:33 AM on February 21, 2015

Best answer: Yes. Wireshark would be appropriate.

I'd start with logs from the DHCP service, the switch, and the AP. It will take less effort, and may show what the problem is right up front.
posted by graftole at 8:44 AM on February 21, 2015

Does your DHCP server only allow whitelisted MAC addresses or ranges?
posted by tomierna at 8:46 AM on February 21, 2015

You say at work -- is your IT department using MAC address filtering on the network? The symptoms seem to line up.

EDIT: What tomierna said.
posted by drfu at 2:52 PM on February 21, 2015

Response by poster: The IT department? C’est moi. There is no MAC address filtering or anything else that would restrict a device from getting a dynamic IP address.
posted by alex1965 at 6:32 PM on February 21, 2015

Some routers allow you to assign a static IP address to a MAC address - can you get the MAC/s for the speaker/s and manually assign an IP via your router web-interface based on that?
posted by quinndexter at 7:48 PM on February 21, 2015

If you can turn up the verbosity of the DHCP server's log, as graftole says, that's a good place to start.

When that doesn't turn anything up, Wireshark will be the next tool, but you'll need to either plug your machine and the device into a hub or clone the port you plug it into on the switch so you can see the traffic.
posted by tomierna at 8:09 PM on February 21, 2015

This could be a UPnP thing.
posted by casual observer at 9:38 PM on February 21, 2015

Response by poster: Thanks for the tips. I'll work on this project some more in a couple of weeks, and then I'll post an update. In the meantime, I'm marking this question as resolved.
posted by alex1965 at 9:20 AM on March 1, 2015

Response by poster: An update: I implemented Graftole's suggestion and used Wireshark. The DHCP server was offering an IP address in the 192.168.50.x subnet, but the speaker was rejecting the address. My co-worker suggested creating a new scope using 192.168.1.x. Once we did that, the speaker accepted the IP address. Not sure what possible reason there would be for rejecting dot-50 addresses, but there you have it.
posted by alex1965 at 12:50 PM on March 23, 2015

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