Date: Mon, 16 Sep 2024 16:05:39 -0400 From: Chris Ross <cross+freebsd@distal.com> To: freebsd-net@freebsd.org, Roy Marples <roy@marples.name> Cc: Chris Ross <cross+freebsd@distal.com> Subject: IPv6 neighbor flaps for ISP router are occurring frequently Message-ID: <89F4F5A4-E3D9-4A43-84F6-908E3FA221A6@distal.com>
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Hello. Following the earlier thread "DHCPv6 IA_PD - how-to=E2=80=9D I =
have been
bringing up a new gateway router for my network. With Roy=E2=80=99s =
help, I
have IPv6 working as expected, but I am seeing something that I suspect
is unusual. Roy doesn=E2=80=99t think it=E2=80=99s specific to dhcpcd, =
as it is caused
by routing changes that dhcpcd is merely reacting to.
While dhcpcd is running, it repeatedly logs the following to daemon.log:
Sep 16 15:55:53 logrus dhcpcd[50070]: vlan0: fe80::3e8a:b0ff:fe3e:4dce =
is unreachable
Sep 16 15:55:54 logrus dhcpcd[50070]: vlan0: fe80::3e8a:b0ff:fe3e:4dce =
is reachable again
Sep 16 15:55:54 logrus dhcpcd[50070]: vlan0: soliciting an IPv6 router
Sep 16 15:56:25 logrus dhcpcd[50070]: vlan0: fe80::3e8a:b0ff:fe3e:4dce =
is unreachable
Sep 16 15:56:25 logrus dhcpcd[50070]: vlan0: fe80::3e8a:b0ff:fe3e:4dce =
is reachable again
Sep 16 15:56:25 logrus dhcpcd[50070]: vlan0: soliciting an IPv6 router
Sep 16 15:56:57 logrus dhcpcd[50070]: vlan0: fe80::3e8a:b0ff:fe3e:4dce =
is unreachable
Sep 16 15:56:58 logrus dhcpcd[50070]: vlan0: soliciting an IPv6 router
Sep 16 15:56:58 logrus dhcpcd[50070]: vlan0: Router Advertisement from =
fe80::3e8a:b0ff:fe3e:4dce
Sep 16 15:57:32 logrus dhcpcd[50070]: vlan0: fe80::3e8a:b0ff:fe3e:4dce =
is unreachable
Sep 16 15:57:32 logrus dhcpcd[50070]: vlan0: soliciting an IPv6 router
Sep 16 15:57:32 logrus dhcpcd[50070]: vlan0: Router Advertisement from =
fe80::3e8a:b0ff:fe3e:4dce
During this same time frame, =E2=80=9Croute monitor=E2=80=9D shows:
15:55:53.573 PID 0 delete neigh fe80::3e8a:b0ff:fe3e:4dce%vlan0 state =
PROBE lladdr 3c:8a:b0:3e:4d:ce iface vlan0 15:55:54.002 PID 0 =
add/repl neigh fe80::3e8a:b0ff:fe3e:4dce%vlan0 state REACHABLE lladdr =
3c:8a:b0:3e:4d:ce iface vlan0 15:56:25.148 PID 0 delete neigh =
fe80::3e8a:b0ff:fe3e:4dce%vlan0 state PROBE lladdr 3c:8a:b0:3e:4d:ce =
iface vlan0 15:56:25.212 PID 0 add/repl neigh =
fe80::3e8a:b0ff:fe3e:4dce%vlan0 state REACHABLE lladdr 3c:8a:b0:3e:4d:ce =
iface vlan0 15:56:57.406 PID 0 delete neigh =
fe80::3e8a:b0ff:fe3e:4dce%vlan0 state PROBE lladdr 3c:8a:b0:3e:4d:ce =
iface vlan0 15:56:58.967 PID 0 add/repl neigh =
fe80::3e8a:b0ff:fe3e:4dce%vlan0 state REACHABLE lladdr 3c:8a:b0:3e:4d:ce =
iface vlan0 15:57:32.325 PID 0 delete neigh =
fe80::3e8a:b0ff:fe3e:4dce%vlan0 state PROBE lladdr 3c:8a:b0:3e:4d:ce =
iface vlan0 15:57:34.143 PID 0 add/repl neigh =
fe80::3e8a:b0ff:fe3e:4dce%vlan0 state REACHABLE lladdr 3c:8a:b0:3e:4d:ce =
iface vlan0 =20
My concern is that this is sending RS=E2=80=99s to my provider far too =
often.
Can anyone advise if this is normal, and assuming not, what might
be wrong?
Trimmed dhcpcd.conf is:
duid
persistent
vendorclassid
option classless_static_routes
option rapid_commit
require dhcp_server_identifier
slaac private
noipv6rs
noipv4
noipv4ll
allowinterfaces vlan0
interface vlan0
ipv6only
ipv6rs
ipv6ra_autoconf
ia_pd 0/::/56 intnet1/42 intnet2/56
Thanks.
- Chris
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