Endless lan IPv6 Router Advertisements

Installing and Using OpenWrt Network and Wireless Configuration
1

For some reason dhcpcd on my Linux desktop appears to be reconfiguring every 2-10 minutes without stop in response to Router Advertisements coming from my router (a TL-WR841ND v8 flashed with OpenWRT 17.01.7). This does not seem to be a problem between the router and my internet provider on the wan/wan6 side. From my desktop's /var/log/messages:

...
Feb 10 01:07:16 kestralis dhcpcd[1824]: eth0: Router Advertisement from fe80::6666:b3ff:fe9d:172a
Feb 10 01:09:01 kestralis dhcpcd[1824]: eth0: RECONFIGURE6 from fe80::6666:b3ff:fe9d:172a
Feb 10 01:09:01 kestralis dhcpcd[1824]: eth0: REPLY6 received from fe80::6666:b3ff:fe9d:172a
Feb 10 01:09:01 kestralis dhcpcd[1824]: eth0: adding address 2600:6c67:467f:e831::100/128
Feb 10 01:09:01 kestralis dhcpcd[1824]: eth0: renew in 216000, rebind in 345600, expire in 4294967295 seconds
Feb 10 01:09:02 kestralis dhcpcd[1824]: eth0: Router Advertisement from fe80::6666:b3ff:fe9d:172a
Feb 10 01:11:59 kestralis dhcpcd[1824]: eth0: RECONFIGURE6 from fe80::6666:b3ff:fe9d:172a
Feb 10 01:11:59 kestralis dhcpcd[1824]: eth0: REPLY6 received from fe80::6666:b3ff:fe9d:172a
Feb 10 01:11:59 kestralis dhcpcd[1824]: eth0: adding address 2600:6c67:467f:e831::100/128
Feb 10 01:11:59 kestralis dhcpcd[1824]: eth0: renew in 216000, rebind in 345600, expire in 4294967295 seconds
Feb 10 01:12:00 kestralis dhcpcd[1824]: eth0: Router Advertisement from fe80::6666:b3ff:fe9d:172a
...

My router is configured to be serve both RAs and DHCPv6 in "server" mode, with leases set to 12 hours by default. The Linux desktop also has a static lease setup. For reference, here is my router's /etc/config/dhcp:

config dnsmasq
        option domainneeded '1'
        option filterwin2k '0'
        option localise_queries '1'
        option rebind_protection '1'
        option rebind_localhost '0'
        option local '/lan/'
        option domain 'lan'
        option expandhosts '1'
        option nonegcache '1'
        option authoritative '1'
        option nonwildcard '1'
        option readethers '1'
        option leasefile '/tmp/dhcp.leases'
        option resolvfile '/tmp/resolv.conf.auto'
        option localservice '1'
        list server '*<redacted>*'
        list server '*<redacted>*'
        list server '*<redacted>*'
        list server '*<redacted>*'
        list server '*<redacted>*'
        list server '*<redacted>*'

config dhcp 'lan'
        option interface 'lan'
        option start '100'
        option limit '150'
        option leasetime '12h'
        option dhcpv6 'server'
        option ra 'server'

config dhcp 'wan'
        option interface 'wan'
        option ignore '1'

config odhcpd 'odhcpd'
        option maindhcp '0'
        option leasefile '/tmp/hosts/odhcpd'
        option leasetrigger '/usr/sbin/odhcpd-update'

config host
        option name '*<redacted>*'
        option mac '*<redacted>*'
        option duid '*<redacted>*'
        option ip '192.168.10.113'
        option hostid '100'
        option dns '1'
        option leasetime '120h'

config domain

My desktop's network connection at least seems quite solid, but I'm assuming these messages hint at a misstep in my configuration. What can I do (or try) to correct this? Any suggestions appreciated.

2

They should be every 5. I do personally observe some occasionally in between these intervals.

Nonetheless, can you explain what issues you're experiencing because of it?

https://openwrt.org/docs/techref/odhcpd

See: ra_mininterval

3

My initial concern was that my router seemed to be sending too many RAs, and often they were being sent sooner than value set for ra_mininterval. Changing this value partly works, and fewer RAs are sent but many RAs still come sooner than mininterval. Through some helpful folks at LinuxQuestions the problem actually seems to be that the router is sending too many RECONFIGURE messages, which (if I'm understanding correctly) is why many RAs routinely come sooner than the value set for ra_mininterval. A user at LQ also suggested that my ISP might be responsible for forcing these RECONFIGUREs on their side, but I don't know how to check this yet.

Overall, my IPv6 connectivity seems stable and it's mostly a matter of what seems to be unnecessary overhead for my client machine to handle so many unneeded RECONFIGURE messages (they rarely seem to ever add or remove addresses or routes) and the accompanying dhcpcd chatter filling said machine's logs.

I'm assuming I misconfigured the router, but unsure what my next step should be to figure out the source of these RECONFIGURE messages and ultimately reduce the number being passed onto client machines served by the router.

4

Turn off DHCPv6 on your network and use SLAAC?

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