Problematic Buster dhcpcd lease renewal behavior

bls s

Sat Dec 19 22:50:17 2020

I'm seeing a problematic dhcpcd behavior difference on a Raspberry Pi between Stretch (dhcpcd 6.11-5) and Buster (dhcpcd 8.1.2) when used on
the built-in WiFi.

On my network, once the DHCP lease time is 50% expired, the Buster dhcpcd starts requsting a new DHCP address every minute or so, for what appears to be forever.

Contrast that with Stretch dhcpcd where the lease was correctly renewed and there were no extraneous DHCP requests.

For some reason that I can't sort out, Buster dhcpcd thinks that the DHCP server ACK is not good, sends an ICMP destination unreachable packet, and then goes into a state that I've never seen before, eventually getting a lease but shortly thereafter restarts the cycle.

Both tests were run on the same Pi, against the same isc-dhcp-server 4.4.1-2. (The DHCP lease time is normally 24 hours, and that's where I first saw this, but I set it down to 10 minutes because who has the patience for that?).

Is there some additional configuration required on either the DHCP server or in dhcpcd to make this work correctly, as it did on Stretch?


Stretch tcpdump: https://1drv.ms/u/s!AnwsNfAZbYjHiZQkxegHpUlf8x21WQ?e=A1K5mc
Stretch syslog:  https://1drv.ms/t/s!AnwsNfAZbYjHiZQmPentFvlj0hmtsw?e=Qx17u1
Buster tcpdump:  https://1drv.ms/u/s!AnwsNfAZbYjHiZQj0AXcOfzzZ6wTUw?e=NMhVi4
Buster syslog:   https://1drv.ms/t/s!AnwsNfAZbYjHiZQlGpb8AcGFKiJFaQ?e=tHL197

Re: Problematic Buster dhcpcd lease renewal behaviorRoy Marples
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