[OpenWrt-Devel] disappearing on-link route with RA

Gui Iribarren gui at altermundi.net
Mon Sep 8 08:59:21 EDT 2014


Hello fine folks,
i'm testing bb-rc, compiled by myself from:
git://git.openwrt.org/14.07/openwrt.git at exactly this commit:
git-svn-id: svn://svn.openwrt.org/openwrt/branches/barrier_breaker@42398

so, a little bit more recent than the published bb-rc3 from
http://downloads.openwrt.org/barrier_breaker/14.07-rc3/

and i encounter a behaviour i'm already getting used to :P [0]

with network.iface.proto=dhcpv6, the first RA that arrives creates the
on-link route correctly (2001:db8::/64 on dev blah)
and the second RA, makes it disappear :(
leaving only the "default" route, and producing "triangular" routing
between nodes on the same link-local

you might not notice this immediately on a wired LAN, but on a
geographically widespread batman-adv mesh network like DeltaLibre, it's
the first thing i notice after sysupgrading, and ssh'ing into a node :)

root at palmeras:~# ip -6 r
default from :: via fe80::a2f3:c1ff:fe86:425 dev br-lan  proto static
metric 1024
default from 2a00:1508:1:f004::/64 via fe80::a2f3:c1ff:fe86:425 dev
br-lan  proto static  metric 1024
2a00:1508:1:f004::/64 dev br-lan  proto static  metric 256
fddf:ca97:c78b::/64 dev br-lan  proto kernel  metric 256
fe80::/64 dev br-lan  proto kernel  metric 256
fe80::/64 dev eth0-167  proto kernel  metric 256
fe80::/64 dev wlan0_ap  proto kernel  metric 256
fe80::/64 dev wlan0_adhoc  proto kernel  metric 256
fe80::/64 dev wlan0_adhoc-167  proto kernel  metric 256
root at palmeras:~# rdisc6 br-lan
Soliciting ff02::2 (ff02::2) on br-lan...

Hop limit                 :           64 (      0x40)
Stateful address conf.    :           No
Stateful other conf.      :           No
Mobile home agent         :           No
Router preference         :       medium
Neighbor discovery proxy  :           No
Router lifetime           :         1800 (0x00000708) seconds
Reachable time            :  unspecified (0x00000000)
Retransmit time           :  unspecified (0x00000000)
 Prefix                   : 2a00:1508:1:f004::/64
  On-link                 :          Yes
  Autonomous address conf.:          Yes
  Valid time              :         3600 (0x00000e10) seconds
  Pref. time              :         3600 (0x00000e10) seconds
 MTU                      :         1500 bytes (valid)
 Source link-layer address: A0:F3:C1:86:04:25
 Recursive DNS server     : 2a00:1508:1:f004::1
  DNS server lifetime     :         1200 (0x000004b0) seconds
 from fe80::a2f3:c1ff:fe86:425
root at palmeras:~# ip -6 r
default from :: via fe80::a2f3:c1ff:fe86:425 dev br-lan  proto static
metric 1024
default from 2a00:1508:1:f004::/64 via fe80::a2f3:c1ff:fe86:425 dev
br-lan  proto static  metric 1024
fddf:ca97:c78b::/64 dev br-lan  proto kernel  metric 256
fe80::/64 dev br-lan  proto kernel  metric 256
fe80::/64 dev eth0-167  proto kernel  metric 256
fe80::/64 dev wlan0_ap  proto kernel  metric 256
fe80::/64 dev wlan0_adhoc  proto kernel  metric 256
fe80::/64 dev wlan0_adhoc-167  proto kernel  metric 256
root at palmeras:~# opkg list odhcp6c netifd
odhcp6c - 2014-08-25-0300fe7589a1701361735ac068e4b57bb1a1896f
root at palmeras:~# opkg list netifd
netifd - 2014-08-31-b2dcb02570939d98b92c7c55db1c328693a5d52a


[0]: i recall encountering a similar regression twice already, in the
last couple of years or so, and in both cases it was promptly fixed by
cyrus: much respect for your impressive work on ipv6! /me always thankful :)

[0a] in fact, i was just looking for the last report
https://lists.openwrt.org/pipermail/openwrt-devel/2014-February/023640.html
and I don't recall specifically, but i guess it worked after that fix,
(or i would have noticed). Anyway i'm not sure anymore :$ sorry for not
following up that original thread, now it's gone from my memory

happy to debug this further, provide pcaps, or anything else needed

cheers! gui
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