DHCPv6 relay doesn't configure a working route

Installing and Using OpenWrt Network and Wireless Configuration
1

So this is my /etc/config/network:

config interface 'loopback'
        option ifname 'lo'
        option proto 'static'
        option ipaddr '127.0.0.1'
        option netmask '255.0.0.0'

config globals 'globals'
        option ula_prefix 'fd46:ed01:2a30::/48'

config interface 'lan'
        option type 'bridge'
        option ifname 'eth1.1'
        option proto 'static'
        option netmask '255.255.255.0'
        option ip6assign '60'
        option ipaddr '192.168.2.1'

config interface 'wan'
        option ifname 'eth0.2'
        option proto 'dhcp'

config interface 'wan6'
        option ifname 'eth0.2'
        option proto 'dhcpv6'
        option reqaddress 'try'
        option reqprefix 'auto'

config switch
        option name 'switch0'
        option reset '1'
        option enable_vlan '1'

config switch_vlan
        option device 'switch0'
        option vlan '1'
        option ports '1 2 3 4 0t'

config switch_vlan
        option device 'switch0'
        option vlan '2'
        option ports '5 6t'

config interface 'relay_bridge'
        option proto 'relay'
        list network 'lan'
        list network 'wan'
        option ipaddr '192.168.178.2'
        option force_link '1'

config interface 'relay6_master'
        option ifname 'eth0.2'
        option proto 'static'
        option netmask '255.255.255.0'
        option ipaddr '192.168.2.1'
        option force_link '0'

and my /etc/config/dhcp:

config dnsmasq
        option domainneeded '1'
        option localise_queries '1'
        option rebind_protection '1'
        option rebind_localhost '1'
        option local '/lan/'
        option domain 'lan'
        option expandhosts '1'
        option readethers '1'
        option leasefile '/tmp/dhcp.leases'
        option resolvfile '/tmp/resolv.conf.auto'
        option localservice '1'

config dhcp 'lan'
        option interface 'lan'
        option ignore '1'
        option ra 'relay'
        option dhcpv6 'relay'
        option ndp 'hybrid' # Also tried relay here

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'
        option loglevel '4'

config dhcp 'wan6'
        option interface 'wan6'
        option ignore '1'

config dhcp 'relay6_master'
        option interface 'relay6_master'
        option ra 'relay'
        option ndp 'relay'
        option dhcpv6 'relay'
        option master '1'
        option ignore '1'

Clients get IPv6 adresses correctly, the default route also seems to be valid:

C:\Users\V10lator>ipconfig

Windows-IP-Konfiguration


Ethernet-Adapter Ethernet:

   Verbindungsspezifisches DNS-Suffix: fritz.box
   IPv6-Adresse. . . . . . . . . . . : 2001:a61:347e:901:dc88:af04:6e33:3b45
   IPv6-Adresse. . . . . . . . . . . : fd00::dc88:af04:6e33:3b45
   IPv6-Adresse. . . . . . . . . . . : fd46:ed01:2a30::507
   IPv6-Adresse. . . . . . . . . . . : fdf8:b879:e2a8::507
   Temporäre IPv6-Adresse. . . . . . : 2001:a61:347e:901:b172:4133:eec2:221f
   Temporäre IPv6-Adresse. . . . . . : fd00::b172:4133:eec2:221f
   Verbindungslokale IPv6-Adresse  . : fe80::dc88:af04:6e33:3b45%14
   IPv4-Adresse  . . . . . . . . . . : 192.168.178.42
   Subnetzmaske  . . . . . . . . . . : 255.255.255.0
   Standardgateway . . . . . . . . . : fe80::1aa6:f7ff:feeb:6624%14
                                       192.168.178.1

C:\Users\V10lator>ping fe80::1aa6:f7ff:feeb:6624%14

Ping wird ausgeführt für fe80::1aa6:f7ff:feeb:6624%14 mit 32 Bytes Daten:
Antwort von fe80::1aa6:f7ff:feeb:6624%14: Zeit=2ms
Antwort von fe80::1aa6:f7ff:feeb:6624%14: Zeit=1ms
Antwort von fe80::1aa6:f7ff:feeb:6624%14: Zeit=1ms
Antwort von fe80::1aa6:f7ff:feeb:6624%14: Zeit=1ms

Ping-Statistik für fe80::1aa6:f7ff:feeb:6624%14:
    Pakete: Gesendet = 4, Empfangen = 4, Verloren = 0
    (0% Verlust),
Ca. Zeitangaben in Millisek.:
    Minimum = 1ms, Maximum = 2ms, Mittelwert = 1ms

but I can't reach any global address:

C:\Users\V10lator>ping -6 google.de

Ping wird ausgeführt für google.de [2001:4860:4802:36::75] mit 32 Bytes Daten:
Zielnetz nicht erreichbar.
Zielnetz nicht erreichbar.
Zielnetz nicht erreichbar.
Zielnetz nicht erreichbar.

Ping-Statistik für 2001:4860:4802:36::75:
    Pakete: Gesendet = 4, Empfangen = 0, Verloren = 4
    (100% Verlust),

The OpenWRT router itself has perfect IPv6 connectivity:

C:\Users\V10lator>ssh root@192.168.178.2
root@192.168.178.2's password:


BusyBox v1.30.1 () built-in shell (ash)

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 -----------------------------------------------------
 OpenWrt 19.07.2, r10947-65030d81f3
 -----------------------------------------------------
root@OpenWrt:~# ping6 google.de
PING google.de (2001:4860:4802:36::75): 56 data bytes
64 bytes from 2001:4860:4802:36::75: seq=0 ttl=57 time=7.897 ms
64 bytes from 2001:4860:4802:36::75: seq=1 ttl=57 time=6.270 ms
64 bytes from 2001:4860:4802:36::75: seq=2 ttl=57 time=6.988 ms
64 bytes from 2001:4860:4802:36::75: seq=3 ttl=57 time=7.284 ms
^C
--- google.de ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 6.270/7.109/7.897 ms

So why is IPv6 routing broken for clients?

2

The DHCPv6 protocol isn't used for route distribution. For that you use the Neighbor Discovery Protocol (ICMPv6 NDP), in particular Router Solicitation and Router Advertisement.

I would run tcpdump -i eth1.1 and tcpdump -i eth0.2 on openwrt to see what happens when you ping from windows.

1 Like
3

Why is there a relay in the first place? Your wan is an ethernet port, not a wifi client and this complicates things with IPv6.

1 Like
4

After rebooting every network component it works but now wifi clients are loosing connection after some time.

//EDIT: And this has been fixed by setting both APs of the roaming network to the same channel.

//EDIT²: Was too fast with this: Drops are still there.

//EDIT³: The WiFi is stable if I disable the DHCPv6 relay (on lan). What's going on here?