12-04-2020 06:23 PM
This one is strange to say the least. About a week ago some devices (Two mac pros and two other devices not windows OS) aren't getting a valid ip address but getting an address from 0.0.0.x with mask 255.255.255.0. The cisco router has a basic configuration, basically with one dhcp pool. This pool is basically just for outside internet access, not for our internal network. I don't think there is a rouge dhcp sever because it's only affecting these 4 devices and only wired, not wireless and strangelyenough it'sonly affecting Mac machines and non windows based devices. The same machine can connect wirelessly to the same subnet with no issues. These devices are on different locations so I don't think it's the switch stack. Maybe a bug? I don't have the ios version the moment but just wondering if anyone has seen this? Also, the only other devices where I get the same addresses is with my fluke, but if I unplug and plug or refresh multiple times I eventually get a valid ip address, unlike the other devices.
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12-04-2020 11:38 PM
Hello,
what if you configure a client reservation for these 'problem' devices ? Here is an example:
ip dhcp pool MAC_PC_1
host 192.168.1.12 255.255.255.0
client-identifier 0100.2413.3c0b.43
12-04-2020 08:05 PM
Hello
have you checked the network properties of the mac ethernet cards - reset them etc..
12-05-2020 08:19 AM
Hello,
This is something I forgot to add, but the device gets an ip if I put thr switch port on a different vlan. So I don't think is the adapter itself. But just to make sure. Can you explain what do you mean by reset them? I already checked the properties but I can't find anything out of thr ordinary, specifically now that I know it works on a different vlan.
12-04-2020 11:38 PM
Hello,
what if you configure a client reservation for these 'problem' devices ? Here is an example:
ip dhcp pool MAC_PC_1
host 192.168.1.12 255.255.255.0
client-identifier 0100.2413.3c0b.43
12-05-2020 08:21 AM
Hello,
That's actually something I can try, and for the number of devices affected it may be an acceptable solution. I've just never seen a device getting this type of ip addresses. The router has been rebooted already as well. And what is more interesting is that only non windows machines aren't getting a valid IP. I just think it's strange.
12-05-2020 09:34 AM
- You may also want to switch over to a dedicated dhcp server outside the router. In the worst case the problem is due to some mis-network-configuration somewhere. From an intranet-design viewpoint it is better to separate networking and dhcp services too. An additional benefit in this case is that a dedicated dhcp server will offer more flexible logging viewing and others. Then also check if it really receives a dhcp request from the mentioned clients (or not).
M.
12-07-2020 05:22 AM
thank you! good to know
12-07-2020 05:21 AM
this is also a good idea. thank you
12-08-2020 05:31 AM
we reserved the ip addresses for these machines and they are working. what i still think is strange is the fact that only these machines are affected and both of them are Mac. thank you
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