DHCP Rebinding Issue - stuck in rebinding until lease times out

RouterOS General
1

Hello,

I’m experiencing an interesting issue. If an interface flaps on the WAN, the dhcp-client issues 2x DHCP Requests unicast to the existing gateway then 2x to broadcast (255.255.255.255) but if if the DHCP server on the network doens’t send back a NAK then it sits there stuck in rebinding state until the DHCP lease expires.

Running RouterOS 6.43.4 on Hex S, also tested on 6.43.1.

Confirmed via PCAPs on a few devices.

Anyone have any idea?

Tim

2

Does anyone know from Mikrotik why after dhcp request during an active lease, if no answer, if it’s configurable to drop the lease and initiate a new discover? Seems most desktop/routers do this periodically but the tik sends 4 renew on the port bounce then nothing until lease expires (just sticks in rebinding) unless it gets a NAK.

Tim

3

I’ve also seen this behavior at times. The Mikrotik DHCP client seems to have no end of little quirks and bugs like this, I wish we could just use udhcp which comes as part of busybox, it’s well tested and should handle these kinds of cases much better.

4

I’m experiencing something similar at the moment, and replied over at http://forum.mikrotik.com/t/dhcp-client-stuck-in-rebinding-state-when-moved-to-new-network/87904/5

5

gah… this is still an issue for me as well. RouterOS v6.43.12. I disable/enabled the dhcp client and it comes back online cleanly. Anyone out there have any luck working around this bug with mikrotik capability with cable modems?