DHCP suddenly not working anymore

[^rooker]

[PROBLEM]
For no reason at all, a properly functioning network suddenly won't receive DHCP information - even rerequesting them won't work.

[SOLUTION]
Try unplugging the power of your network-switch, wait a few seconds and then plug it back in. For some reason they might 'hang'.
(We're having this problem approx. every 4-5 months with SureCom switches)

[^rooker]

I'm adding this post, because I just had the same problem right now and couldn't remember that I even wrote it down 4 years ago!

So I'll add some keywords here:
* Bootserver
* PXE
* Network boot

And some additional information:
* The DHCP server didn't even receive any requests anymore (nothing visible in /var/log/daemon.log or /var/log/messages.

* It was working fine for other computes on the LAN: Yes, because they were connected to a different switch/hub.

* The uplink and status LEDs of the SureCom switch are perfectly, misleadingly fine - AND: if you already have an IP address on a computer on the same switch, network works fine.


This one's a bitch!