Duplicate ip addresses - even after reserving an address based on MAC address?

Question

Duplicate ip addresses - even after reserving an address based on MAC address?

So I have an Airport Extreme Base Station on which I have reserved an IP address for my wireless IP camera, using the MAC address of the camera for the reservation. I have also limited my pool of IP addresses available for DHCP to below the number that I have set aside for my camera. However my wireless Epson printer repeatedly ends up with the same IP address as my camera and I don't understand how. Aside from the annoyance of having to shut down and restart my printer whenever I actually want to send a print to it, the bigger issue is that the IP address duplication is causing my motion sensing monitoring software to fail to connect reliably to my IP camera. It's also preventing me from connecting via port forwarding to my camera when away from the house.

I've decided to try assigning a reserved IP address to my printer as well, but I'm wondering why this is happening, and what would stop another device taking the IP address from the camera.

Any one with thoughts or suggestions as to what might be happening?

Many thanks

Posted on Aug 16, 2013 7:54 PM

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Answer 1

Aug 16, 2013 9:06 PM in response to Mike O'Sullivan

Apart from the obvious typo in the MAC address you are reserving. A non-apple product may be using dhcp in a non-apple way and reaping the rewards of it by not being given its special place at the table.. !!

Try giving IP addresses outside the dhcp range.. I am not sure wth the apple routers. sometimes it won't work but it really should.

A static IP on the camera outside dhcp range should also fix it.

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Answer 2

Aug 20, 2013 5:54 PM in response to LaPastenague

It's not a typo, the camera's MAC address is entered correctly and gets allocated the assigned IP address of 192.168.0.178. The range of addresses available for DHCP has been limited to a max of 192.168.0.150.

It just seems that the Epson printer is hijacking the IP address assigned to the camera. even though I've tried giving the printer it's own assigned address it just doesn't seem to want to use it.

The camera is an 802.11 b/g device whilst the printer is an 80211 b/g/n device - would the different bands be contributing to the IP address confusion?

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Answer 3

Aug 20, 2013 6:13 PM in response to Mike O'Sullivan

No, I don't think so as both are actually 2.4ghz and it should not matter anyway.. but both are non-apple products and may deal with dhcp in ways the airport is not designed to see..

As a strange question how close are the MAC addresses.. it is super weird to have both getting the same IP when that address is outside the dhcp range.

But now I need to know also why are you using non-standard IP? How hard is it to go back to factory settings and just run it at default IP, ie 10.0.1.x??

Is the Airport actually the main router in the network or do you have more than one router and double NAT.

I do not know what happens in this situation with the Airports but I have used other routers that worked fine on their default IP and actually fail on something else.. again I am not saying this is the problem.. but I have seen it before because the router firmware has built in IP addresses where it should have had variable that was filled in by the selection of home IP.

The only way to really find out is connect a managed switch with a mirrored port and run wireshark or equivalent to watch the dhcp discovery actually happen. But that is getting too complicated and it is easier to just give devices a static IP directly on the printer or camera.. as well as assigning them by dhcp to ensure they are registered in the ARP table.

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