[6bone] Problem with Autoconfiguration when using 802.1Q encapsulation

[Enric Corominas i Bosch]

Dear All,

I'm trying to configure a Debian host as an IPv6 firewall. I have just one ethernet card, so I've been playing with
802.1Q, configuring three let's call "subinterfaces".

I use the software from candelatech (http://www.candelatech.com/~greear/vlan.html) to create the subinterfaces, and everything seems to work fine, the interfaces creates link local addresses, they are recognized by the switch, and the communication is fine.

Also I can give the subinterfaces an IPv6 address, and announce it with "radvd" (latest version, 0.7.2). 

>=======================================>
almodis:/home/enric/vlan/vlan# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:00:E8:79:C0:43  
          inet6 addr: fe80::200:e8ff:fe79:c043/10 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:140467 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6546 errors:36 dropped:0 overruns:0 carrier:72
          collisions:623 txqueuelen:100 
          RX bytes:10607455 (10.1 MiB)  TX bytes:1022885 (998.9 KiB)
          Interrupt:5 Base address:0xe400 

eth0.2    Link encap:Ethernet  HWaddr 00:00:E8:79:C0:43  
          inet addr:213.164.61.200  Bcast:213.164.61.255  Mask:255.255.255.192
          inet6 addr: fe80::200:e8ff:fe79:c043/10 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:36645 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6497 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:3711593 (3.5 MiB)  TX bytes:1002537 (979.0 KiB)
>=======================================>


But I've detected that the interface is not able to autoconfigure when receiving an "Router Advertisement"
The RA is received correctly, but is ignored.


>=======================================>
Router advertisement from fe80::230:94ff:fe0a:b420 (hoplimit 255)
Received by interface eth0.2
        # Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump
        AdvCurHopLimit: 64
        AdvManagedFlag: off
        AdvOtherConfigFlag: off
        AdvHomeAgentFlag: off
        AdvReachableTime: 0
        AdvRetransTimer: 0
        AdvSourceLLAddress: 00 30 94 0A B4 20 
        Prefix 3ffe:400a:0:803::/64
                AdvValidLifetime: 2592000
                AdvPreferredLifetime: 604800
                AdvOnLink: on
                AdvAutonomous: on
                AdvRouterAddr: off
>=======================================>


I have looked into "/proc/sys/net/ipv6/conf/eth0.2", and "accept_ra" is set to "1", it is TRUE, so it should autoconfigure to the received prefix.

If I try to set the value to "1" or "0" by hand using "sysctl", it gives a syntax error, as it seems not to recognize the "." in the name of the interface, changing it for a "/"


>=======================================>
almodis:/proc/net# sysctl -w net/ipv6/conf/eth0.2/accept_ra=1
error: 'net/ipv6/conf/eth0/2/accept_ra' is an unknown key
almodis:/proc/net# 
>=======================================>

This make me think of a kind of bug, but I can't imagine how to resolve it.

Another point I have seen is that the LINK LOCAL address has the same value in both "eth0" and "eth0.2", I don't know if this can have any relation with the ignoring of the router advertisement.

Any one has tried a similar configuration ? Any ideas ?

Thanks in advance,

Enric Corominas i Bosch
****************************************************************
Enric Corominas i Bosch             enric@satec.es
Network Engineer        

Satec S.A   http://www.satec.es
Edif. TESTA Sant Cugat
Ṃdul A, Planta 1                      Tlf:  +34 93 581 67 00
C/Alcalde Barnils, 64-68             Fax:+34 93 581 67 01
Sant Cugat del Valles                 08190 BARCELONA 
****************************************************************