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Running a network behind a ZyWall USG 200. Our subnet has around 100-110 devices connected at any particular time. Recently some users were having trouble with getting a DHCP address (keep getting self-assigned IPs) and upon investigation I noticed that there were 150-200 addresses assigned in the DHCP table on the router. I looked into the table and it is showing one or two devices with 30-50 IPs assigned:
I think that this is filling up the available address range and preventing other devices from leasing an IP. Interestingly, as I refresh the table this number fluctuates and different devices are hogging the addresses.
Why would this be happening? How can I prevent this so that all devices can pull an IP and connect to the internet?
TIA
aaaarrgh
Posted 2014-03-31T19:08:30.427
Reputation: 131
is there any way to assign static DHCP addresses within the firewall? A static DHCP lease would make it so every time a particlar device sees a request from a given mac address, it will ALWAYS assign the same 'static' ip address to that device. That way you do not have devices grabbing 30-50 dynamic IP addresses. Usually you only want to set static leases on devices like servers, printers (things that are not likely to move, unlike laptops). Come up with an acceptable DHCP scope that can accommodate a number of dynamic addresses and a number of DHCP static leases. – Richie086 – 2014-03-31T20:45:00.973
Let me know if your firewall has this ability and give some additional details on your network range and what sorts of devices are on the subnet. – Richie086 – 2014-03-31T20:46:05.743
I have 8 devices with static addresses. I've set the DHCP range to be .21 thru .254, and reserve the .2 thru .20 addresses for statics. I assign the statics using the IP/MAC binding feature of the router, and there is no issue with these devices. This setup has been working for almost a year, and today is the first time that I've ever seen this glut of addresses by single devices. – aaaarrgh – 2014-03-31T21:01:29.843
The static IPs are a NAS, the switch, two WAPs, and a couple of servers that handle some inward-facing web-based services (continuous integration, a custom in-house test server, etc). The DHCP devices are a pretty even mix of Win7/8, MacOS, iOS and Android devices, along with two printers. – aaaarrgh – 2014-03-31T21:03:20.420
So, what what are the devices that are hogging the IP space? Laptops? Desktops? Maybe set the up as static leases to eliminate the problem – Richie086 – 2014-03-31T21:05:01.670
The items that are hogging space have been changing, but they seem to be exclusively laptops - a couple of Macbook Pros, an Asus win8.1 laptop. It seems to be inconsistent. But at least some of these devices were also without connectivity at the same time that they were hogging addresses. Notice in the screenshot that the device doesn't show a MAC address. This was alwyas true for devices with no connectivity. If the machine had connectivity, only the first entry for the host would show a MAC, the others did not. – aaaarrgh – 2014-03-31T21:08:03.567
cant really tell too much from that screenshot... I do not see any column headers that would tell me what information each column has in it. Is it possible to show the lease duration for each request? – Richie086 – 2014-03-31T21:10:04.800
Looks like this sort of thing might be a common issue with many apple devices. check this out https://discussions.apple.com/message/9063792#9063792 and http://apple.stackexchange.com/questions/12343/2010-macbook-pro-does-not-dhcp-on-a-certain-network-wifi-and-ethernet
– Richie086 – 2014-03-31T21:13:25.877After reading a few posts about this, do you have IPv6 enabled or is IPv6 in use on your network? – Richie086 – 2014-03-31T21:17:17.633
Richie -- thanks for all of your help on this. Unfortunately this has been a big enough impact that we just went out and replaced the router - the one time hit to the books pays off in the man hours of productivity we were losing. So the issue is not resolved but is effectively closed. – aaaarrgh – 2014-04-01T00:37:42.323
Ah, that sucks. Well at least this should work out for you. That's what matters. :) – Richie086 – 2014-04-01T05:17:31.970