dhcpcd-discuss

Hi Floris

On 19/10/2019 12:14, Floris Bos wrote:
> There seems to be a problem in which a network interface is sometimes 
> not get assigned an IPv6 link local address if the network interface 
> goes quickly up -> down -> up again.
>
>
> - dhcpcd version 7.0.8 that is shipped with Raspbian
>
> ==
>
>
> dhcpcd claims that the carrier quickly goes up -> down -> up again. It 
> does assign IPv6 link local the first time link goes up, but fails to do 
> so second time.
>
>
> ==
>
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: waiting for carrier
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: carrier acquired
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: IAID 60:99:b3:1e
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: adding address 
> fe80::4d92:7daa:a2d7:b46
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: carrier lost
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: deleting address 
> fe80::4d92:7daa:a2d7:b46
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: carrier acquired
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: IAID 60:99:b3:1e
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: soliciting an IPv6 router
> Oct 19 11:48:16 raspberrypi dhcpcd[395]: usb0: soliciting a DHCP lease
> Oct 19 11:48:21 raspberrypi dhcpcd[395]: usb0: probing for an IPv4LL 
> address
> Oct 19 11:48:26 raspberrypi dhcpcd[395]: usb0: using IPv4LL address 
> 169.254.140.228
> Oct 19 11:48:26 raspberrypi dhcpcd[395]: usb0: adding route to 
> 169.254.0.0/16
> ==
>
>
> - The problem does not occur on a Pi 4 and a Pi 1 using the same SD 
> card. (interface does go up -> down -> up, but it does get an IPv6 link 
> local address assigned)
>
> And it is not 100% reproducible on a Pi 3+B either, but does happen 
> often on that.
>
> Therefore I believe the problem is timing specific
>
> - Other reports: 
> https://www.raspberrypi.org/forums/viewtopic.php?f=91&t=254541

Using dhcpcd-8.1.1 I ran the following script on a Linux VM

while true; do ip link set down dev eth0; ip link set up dev eth0; sleep 
3; done

Each time the link went down, dhcpcd removed the LL address and each 
time it came up dhcpcd added it back.

Could you try upgrading please and see if it's still an issue?

Roy