USG110 - DHCP Discover failed on WAN1 Port

USG_User

Thanks for your effort Peter.

Peter_UK wrote:

"however looking at your NAK vs my NAK the Client IP address and Your (client) IP address is 192.168.2.3 vs your 0.0.0.0 maybe thats the reason?"

No it doesn't. Our USG is sending REQUESTs always with its assigned client IP by unicast to ISP's DHCP server IP. In case the DHCP server is answering with a NAK (instead of ACK), the USG is immerdiately rejecting its IP and is continuously sending REQUESTs by broadcast from 0.0.0.0 to 255.255.255.255 from this moment. But without success since ISP's DHCP server is reacting to DISCOVER packets on broadcast only and not on REQUESTs on broadcast.

But anyway, I'm not an expert on DHCP programming. But what I see on standard DHCP block diagrams like above in my seconds post ..., whenever receiving a NAK packet, the client has to restart with a new INIT by DHCP_DISCOVER. From my point of view, there is no other option.

And this is exactly the behaviour what I recognize on your packet captures. When your devices receive a NAK, they reject their assigned IPs and make a broadcast DISCOVER from 0.0.0.0 to 255.255.255.255 as expected, but never a REQUEST on broadcast without an OFFER from DHCP server.

USG_User

Finally Zyxel provided us with a WK32 firmware which fix the issue. Now USG110 is correctly answering with a new DHCP DISCOVER after receiving a DHCP NAK from ISP's DHCP server. Thanks to Zyxel_Stan for excellent cooperation.

Hope that the fix will be permanently integrated into next official firmware release.

USG_User

Finally Zyxel provided us with a WK32 firmware which fix the DHCP issue. Now our USG110 answeres correctly with a new DHCP DISCOVER after receiving a DHCP NAK packet from ISP's DHCP server. Special thanks to Zyxel_Stan for excellent cooperation.

Hope the fix will be permanently integrated into next official FW release.

Zyxel_Stanley

Hi @USG_User
It's good to know the firmware helps in your case.

mMontana

@Zyxel_Stanley there's any ETA for WK32 corrections to be merged into ZLD 4.X firmware?

Edit:
After a "little search" i was quite... astonished by the WK32 release of the lab firmware (two weeks old)
https://support.zyxel.eu/hc/en-us/articles/360005438274-Weekly-Firmware-Support-Version-Lab-Version

4.65 is WK32, but P0, not P1.
5.02 is WK32. but P0, not P1.
And I cannot see 5.10. But maybe... it's fine and I am only... without enough information to understand

Zyxel_Stanley

Hi @mMontana

We typo wrong version in website. We will correct it.
Thanks for your kind reminder.

USG_User

Hi Stan,

Just learnt from mMontana's post above that there are different download opportunities for WK firmwares in place:

1: https://community.zyxel.com/en/discussion/11213/zld-v5-02-4-65-wk28-firmware-release#latest 

2: https://support.zyxel.eu/hc/en-us/articles/360005438274-Weekly-Firmware-Support-Version-Lab-Version

Could you shortly explain Zyxel's policy in this regard. I would prefer to search for beta (WK) versions at one place only avoiding the regular check of changelogs at different places.

Thanks

Zyxel_Stanley

Hi @USG_User
The firmware released on community mainly is for world wide users who may not visit EU support page directly but using the community website instead.

However, the downloaded firmwares in the same version from both sites will be no difference.