[Wien] ipv6 with olsrd2?

[Markus Kittenberger]

my 2 cents are that bridges without WDS already cause ipv4 problems and not
only issues with ipv6, so they should never have been used.

Unfortunately i fear there are still quite a few of them in our network.

lg Markus

On Tue, Aug 15, 2017 at 12:07 PM, Erich N. Pekarek <(spam-protected)> wrote:

> Hi!
> Am 2017-08-15 um 11:43 schrieb Matthias Šubik:
>
>> let me have a guess ...
>>
> Let me guess a bit further...
>
>> On 11 Aug 2017, at 15:37, Gui Iribarren <(spam-protected)> wrote:
>>>
>>> On 11/08/17 13:43, Christian Pock wrote:
>>>
>> ...
>>
>>>
>>>> For some reason, not all routers running olsr2 are reachable via IPv6.
>>>> As far as we found out, this is related to the  setting "WDS bridge" on
>>>> Ubiquiti-Antennas running AirOS 6 or earlier (with must be enabled). So in
>>>> case there's a node listed in the "olsr2 cloud", a missing
>>>> WDS-bridge-enabled setting could cause that the node is not available
>>>> (highlighted blue in the listing and map).
>>>>
>>> yeah, "WDS" must always be enabled on all bridges (in some AirOs
>>> versions is called "Transparent bridge mode") or funny things happen in
>>> IPv6 world
>>>
>> I don’t know AirOS, but I guess if disabled, it filters ethernet
>> multicast, this kills neighbour discovery, which is essential for normal
>> IPv6 operation.
>> If you debug IPv6, please take into account the subtile differences
>> between IPv4 and IPv6 on layer two.
>>
> Multicast is not the only problem. Since AirOS is used in bridged mode,
> you'd then have 'foreign' MAC addresses leaving the Wireless Interface.
> This is, what WDS is usually for: it resembles 4-address mode, that
> rewrites packets.
>
> The effect of using a non-WDS-bridge would be, that ip neigh show would
> list the neighbours correctly, but all of them will be STALE in the first
> place.
> If you try to ping them, you will fail, which will be represented by a
> FAILED link in die neighbour table.
> The funny thing is, that you could still ping6 the link local address from
> a direct 1 hop neighbour.
>
> So you may be lead to believe it's a mere multicast problem. But debugging
> that, you will see, that proxying the multicast won't help.
> The problem resides in NDP failing to resolve devices behind the bridge,
> since it will only discover the wrong originator MAC - that is the one of
> the AP on non-WDS-enabled devices.
>
>
>> TL;DR: ARP reachability is not v6 reachability.
>>
> Full Ack.
>
>>
>> just a little reminder,
>> Matthias
>>
>>
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>> Best regards
>>
> Erich
>
>
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