Can anyone she some light on a problem I am experiencing.

I have two draytek routers a 2860 and a 2862. The primary router is the 2862, but occasionally I switch over the two to ensure I have a working backup.
This weekend I switched over, however I noticed that the 2860 had new firmware so I upgrade (3.9.1) at the same time.

It ran fine over the weekend, but as I stated work this morning, I started experiencing network problems.

After investigating I noticed the primary network switch was showing a conflicted IP assignment, I assume this means two devices on the same address.
Now here is the rub, because it's the primary network switch, I give it a fixed up address so nothing else should get that IP. But as I monitored the DHCP table I also noticed the switch getting a different IP address.

Thinking maybe it was just because I hadn't rebooted the switch , I thought let's go with a reboot. Same problem, always a conflicted IP address and it was moving between one of two IP address, I fixed one and another one.

My next step was to switch back to the 2862, when I did, c everything went back to normal.

Is 3.9.1 duff? Or is there something else going on?

Why not take the static address you assign to the switch out of the DHCP pool, or reserve it on both routers bound to the switch's MAC address (assuming its a managed switch, otherwise it wouldn't have an IP address)

haywardi wrote:
Is 3.9.1 duff?

Neither 3.9.0 nor 3.9.1 are usable on my Vigor 2860n (Previously mentioned: https://forum.draytek.co.uk/viewtopic.php?p=98866#p98866 )

mbames,

Apologies, I can see your point but my description was not accurate.

I do use bind IP to MAC and the reason I said "Fixed IP " is because in the DHCP table this is how it describes the IP allocation.

Hence my confusion that DHCP would allocate a conflict, let alone re-assigned the IP to a different one!

Also the previous versions I was using 3.8.9.1 did not have this problem, hence my perception it was/is 3.9.1 seems to have the real issue here.

I'm not 100% sure how DHCP works, but I thought:

- device makes request for IP
- DHCP server issues IP address (maybe from reservation list), along with renewal period
- Device halfway through renewal period the device makes a broadcast saying "Hey, I have IP, can I keep it?" a DHCP server should respond and say yes.

My guess is that broadcast is somehow not working (either switch issue), or the draytek DHCP server is confused as it says (having switched routers), and thinks "I didn't issue that IP address to that MAC address, so here is a different one".

I could talking talking tosh though, as I only have the briefest understanding of how DHCP works!

Mbames,

Your explanation seems reasonable enough.

However, by switching back to the 2862 I no longer get the conflict strongly indicating the 2860 is at fault and not managing IIP addresses correctly, hence my assertion that 3.9.1 may be faulty.##But I am open to other comments in case it's my understanding that is faulty.