New Member
Posts: 35
Registered: ‎11-02-2010
Kudos: 3

IPv6 router advertisement ignored after "apply" (no default gateway)

We've been putting IPv6 management addresses on our devices (generally RocketM, APs set to bridge mode and wds), but have noticed that they break after making any change (doesn't have to be IP related) and hitting apply. It takes a reboot to fix it, and even then that doesn't always work.

 

It appears that the device (when its not working) is ignoring the router-advertisement from its router, and not installing the default (::0) route as a result. We are using a management vlan. I have not tested to see if this is a problem when not using a management vlan.

 

The behaviour seems to be somewhat inconsistent, I haven't tested it enough to verify that it always breaks after hitting apply, but this was the observed bahaviour while I was trying to track down why it wasn't reachable on IPv6. Once, I did see it fail to work after a reboot, and the second reboot fixed it.

 

I verified that the device is receiving router advertisements via tcpdump in the cli.

current firmware is v5.6.4-cpu400.28969 (XM)

New Member
Posts: 35
Registered: ‎11-02-2010
Kudos: 3

Re: IPv6 router advertisement ignored after "apply" (no default gateway)

And, looking when its working (two different radios):

 

XW.v5.6.4# cat /proc/sys/net/ipv6/conf/br1/accept_ra
1

 

and when its not:

XM.v5.6.4-cpu400.28969.160413.1112# cat /proc/sys/net/ipv6/conf/br1/accept_ra
0

 

rebooting this one...

XM.v5.6.4-cpu400.28969.160413.1112# cat /proc/sys/net/ipv6/conf/br1/accept_ra
1

 

change telnet server to enable and hit apply...

XM.v5.6.4-cpu400.28969.160413.1112# cat /proc/sys/net/ipv6/conf/br1/accept_ra
0

 

change telnet server back to disable and hit apply...

XM.v5.6.4-cpu400.28969.160413.1112# cat /proc/sys/net/ipv6/conf/br1/accept_ra
0

 

reboot radio...

XM.v5.6.4-cpu400.28969.160413.1112# cat /proc/sys/net/ipv6/conf/br1/accept_ra
1

New Member
Posts: 35
Registered: ‎11-02-2010
Kudos: 3

Re: IPv6 router advertisement ignored after "apply" (no default gateway) (still a problem in v8)

Now that IPv6 support has been added to v8, it looks like this problem still exists, making our APs unreachable on IPv6 from anywhere except the router they are directly connected to. Please fix this.

 

XC.v8.5.0# cat /proc/sys/net/ipv6/conf/br1/accept_ra
0
XC.v8.5.0#

 

note the lack of a default gateway:

XC.v8.5.0# ip -6 route
xxxx:xxxx:xxxx:10::/64 dev br1 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev ath0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev ath0.10 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev eth0.10 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev br0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev br1 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0

 

XC.v8.5.0# cat /proc/sys/net/ipv6/conf/ath0/accept_ra
0

XC.v8.5.0# echo 1 >/proc/sys/net/ipv6/conf/ath0/accept_ra
XC.v8.5.0# cat /proc/sys/net/ipv6/conf/ath0/accept_ra
1

 

(modifying br1 by itself didn't work, but setting ath0's accept_ra to 1 works)

 

now there is a default gateway:

XC.v8.5.0# ip -6 route
xxxx:xxxx:xxxx:10::/64 dev br1 proto kernel metric 256 expires 2147033sec mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev ath0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev ath0.10 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev eth0.10 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev br0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev br1 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
default via fe80::ea68:19ff:febd:344b dev br1 proto kernel metric 1024 expires 1676sec mtu 1500 advmss 1440 hoplimit 64
XC.v8.5.0#

 

This is the state after rebooting the AP:

XC.v8.5.0# for i in /proc/sys/net/ipv6/conf/*
> do
> echo $i `cat $i/accept_ra`
> done
/proc/sys/net/ipv6/conf/airview1 0
/proc/sys/net/ipv6/conf/all 0
/proc/sys/net/ipv6/conf/ath0 1
/proc/sys/net/ipv6/conf/ath0.10 1
/proc/sys/net/ipv6/conf/br0 1
/proc/sys/net/ipv6/conf/br1 1
/proc/sys/net/ipv6/conf/default 0
/proc/sys/net/ipv6/conf/eth0 1
/proc/sys/net/ipv6/conf/eth0.10 1
/proc/sys/net/ipv6/conf/eth1 1
/proc/sys/net/ipv6/conf/gre0 1
/proc/sys/net/ipv6/conf/lo 1
/proc/sys/net/ipv6/conf/sit0 1
/proc/sys/net/ipv6/conf/teql0 1
/proc/sys/net/ipv6/conf/tunl0 1
/proc/sys/net/ipv6/conf/wifi0 1
/proc/sys/net/ipv6/conf/wifi1 1
XC.v8.5.0#

 

Pinging xxxx:xxxx:xxxx:10:a:: with 32 bytes of data:
Reply from xxxx:xxxx:xxxx:10:a::: time=8ms
Reply from xxxx:xxxx:xxxx:10:a::: time=4ms

 

And this is the state after changing something on the network tab and "save changes":

 

XC.v8.5.0# for i in /proc/sys/net/ipv6/conf/*
> do
> echo $i `cat $i/accept_ra`
> done
/proc/sys/net/ipv6/conf/airview1 0
/proc/sys/net/ipv6/conf/all 0
/proc/sys/net/ipv6/conf/ath0 0
/proc/sys/net/ipv6/conf/ath0.10 0
/proc/sys/net/ipv6/conf/br0 0
/proc/sys/net/ipv6/conf/br1 0
/proc/sys/net/ipv6/conf/default 0
/proc/sys/net/ipv6/conf/eth0 1
/proc/sys/net/ipv6/conf/eth0.10 0
/proc/sys/net/ipv6/conf/eth1 1
/proc/sys/net/ipv6/conf/gre0 1
/proc/sys/net/ipv6/conf/lo 1
/proc/sys/net/ipv6/conf/sit0 1
/proc/sys/net/ipv6/conf/teql0 1
/proc/sys/net/ipv6/conf/tunl0 1
/proc/sys/net/ipv6/conf/wifi0 0
/proc/sys/net/ipv6/conf/wifi1 1
XC.v8.5.0#

 

Pinging xxxx:xxxx:xxxx:10:a:: with 32 bytes of data:
Request timed out.
Request timed out.

 

Not all changes seem to cause this problem, but some do. After reboot the device becomes reachable again, until someone makes an affecting change again.

Ubiquiti Employee
Posts: 11,657
Registered: ‎04-14-2017
Kudos: 2169
Solutions: 335

Re: IPv6 router advertisement ignored after "apply" (no default gateway) (still a problem

@UBNT-Zy Can we reproduce this in the lab and isolate the cause?
Ubiquiti Employee
Posts: 587
Registered: ‎08-20-2007
Kudos: 137
Solutions: 23

Re: IPv6 router advertisement ignored after "apply" (no default gateway)

New Member
Posts: 35
Registered: ‎11-02-2010
Kudos: 3

Re: IPv6 router advertisement ignored after "apply" (no default gateway)

Just tested this in XC.v8.5.8 and still not working.

 

It appears most of the accept_ra values are set to 1, but its still not picking up its gateway. notably, the all/accept_ra is 0, so I tried setting it to 1 as well, but still didn't work.

 

verified with tcpdump that router advertisements are being received:

 

XC.v8.5.8# find /proc -name accept_ra -print -exec cat {} \;
/proc/sys/net/ipv6/conf/all/accept_ra
0
/proc/sys/net/ipv6/conf/default/accept_ra
0
/proc/sys/net/ipv6/conf/lo/accept_ra
1
/proc/sys/net/ipv6/conf/tunl0/accept_ra
1
/proc/sys/net/ipv6/conf/sit0/accept_ra
1
/proc/sys/net/ipv6/conf/eth0/accept_ra
1
/proc/sys/net/ipv6/conf/eth1/accept_ra
1
/proc/sys/net/ipv6/conf/gre0/accept_ra
1
/proc/sys/net/ipv6/conf/wifi1/accept_ra
1
/proc/sys/net/ipv6/conf/teql0/accept_ra
1
/proc/sys/net/ipv6/conf/wifi0/accept_ra
1
/proc/sys/net/ipv6/conf/ath0/accept_ra
1
/proc/sys/net/ipv6/conf/ath0.17/accept_ra
1
/proc/sys/net/ipv6/conf/eth0.17/accept_ra
1
/proc/sys/net/ipv6/conf/br0/accept_ra
1
/proc/sys/net/ipv6/conf/br1/accept_ra
1
/proc/sys/net/ipv6/conf/airview1/accept_ra
0

 

no default gateway:

 

XC.v8.5.8# ip -6 route get 2001:db8::1
unreachable 2001:db8::1 from :: dev lo table 0 proto kernel src xxxxxx:17:a:: metric 4294967295 error -128 hoplimit 255

 

but do know how to get to our own network:


XC.v8.5.8# ip -6 route get xxxxxx::1
xxxxxx:17::1 from :: via xxxxxx:17::1 dev br1 src xxxxxx:17:a:: metric 0
cache mtu 1500 advmss 1440 hoplimit 0

 

force all/accept_ra to 1

 

XC.v8.5.8# echo 1 > /proc/sys/net/ipv6/conf/all/accept_ra
XC.v8.5.8# cat /proc/sys/net/ipv6/conf/all/accept_ra
1

 

receive an RA:


XC.v8.5.8# tcpdump -i br1 -v icmp6 and ip6[40] == 134
tcpdump: listening on br1, link-type EN10MB (Ethernet), capture size 262144 bytes
12:53:25.091543 IP6 (class 0xc0, hlim 255, next-header ICMPv6 (58) payload length: 96) fe80::xxxxxx > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 96
hop limit 0, Flags [none], pref medium, router lifetime 1800s, reachable time 0s, retrans time 0s
source link-address option (1), length 8 (1): xx:xx:xx:xx:xx:xx
rdnss option (25), length 40 (5): lifetime 900s, addr: xxxxxx addr: xxxxxx
prefix info option (3), length 32 (4): xxxxxx:17::/64, Flags [onlink, auto], valid time 2592000s, pref. time 604800s
^C
1 packet captured
1 packet received by filter
0 packets dropped by kernel

 

but still no gateway:

 

XC.v8.5.8#
XC.v8.5.8# ip -6 route get 2001:db8::1
unreachable 2001:db8::1 from :: dev lo table 0 proto kernel src xxxxxx:17:a:: metric 4294967295 error -128 hoplimit 255
XC.v8.5.8# ping6 2001:db8::1
PING 2001:db8::1 (2001:db8::1): 56 data bytes
ping6: sendto: Network is unreachable

 

accept_ra still 1:

 

XC.v8.5.8#
XC.v8.5.8# find /proc -name accept_ra -print -exec cat {} \;
/proc/sys/net/ipv6/conf/all/accept_ra
1
/proc/sys/net/ipv6/conf/default/accept_ra
0
/proc/sys/net/ipv6/conf/lo/accept_ra
1
/proc/sys/net/ipv6/conf/tunl0/accept_ra
1
/proc/sys/net/ipv6/conf/sit0/accept_ra
1
/proc/sys/net/ipv6/conf/eth0/accept_ra
1
/proc/sys/net/ipv6/conf/eth1/accept_ra
1
/proc/sys/net/ipv6/conf/gre0/accept_ra
1
/proc/sys/net/ipv6/conf/wifi1/accept_ra
1
/proc/sys/net/ipv6/conf/teql0/accept_ra
1
/proc/sys/net/ipv6/conf/wifi0/accept_ra
1
/proc/sys/net/ipv6/conf/ath0/accept_ra
1
/proc/sys/net/ipv6/conf/ath0.17/accept_ra
1
/proc/sys/net/ipv6/conf/eth0.17/accept_ra
1
/proc/sys/net/ipv6/conf/br0/accept_ra
1
/proc/sys/net/ipv6/conf/br1/accept_ra
1
/proc/sys/net/ipv6/conf/airview1/accept_ra
0

 

but no default gateway present:

 

XC.v8.5.8# ip -6 route
xxxxxx:17::/64 dev br1 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev ath0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev ath0.17 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev eth0.17 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev br0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev br1 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 0
XC.v8.5.8#

Ubiquiti Employee
Posts: 11,657
Registered: ‎04-14-2017
Kudos: 2169
Solutions: 335

Re: IPv6 router advertisement ignored after "apply" (no default gateway)

Thanks for your feedback, I will add this to our bug system.