IPv6 gateways with Telekom fibre pppoe setup

[SerErris]

Hi,

i have setup my pppoe connection for telekom and it works in all aspects.

However trying to troubleshoot an another issue I recognized I cannot ping link local addresses on LAN, as I would expect:

If i try

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root@firewall:/var/log/dhcpd # ping6 fe80::be24:11ff:febb:b7fc
PING(56=40+8+8 bytes) fe80::6662:66ff:fe21:b957%pppoe0 --> fe80::be24:11ff:febb:b7fc
^C
--- fe80::be24:11ff:febb:b7fc ping statistics ---
4 packets transmitted, 0 packets received, 100.0% packet loss

The firewall tries to route the traffic via the pppoe link to the internet gateway - probably default route.

However any fe80 traffic (other than the gateway) should be routed to LAN and not to WAN.

if I specify the interface it works:

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root@firewall:/var/log/dhcpd # ping6 fe80::be24:11ff:febb:b7fc%igc0
PING(56=40+8+8 bytes) fe80::6662:66ff:fe21:b957%igc0 --> fe80::be24:11ff:febb:b7fc%igc0
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=0 hlim=64 time=0.338 ms
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=1 hlim=64 time=0.206 ms
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=2 hlim=64 time=0.247 ms
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=3 hlim=64 time=0.231 ms
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=4 hlim=64 time=0.409 ms
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=5 hlim=64 time=0.428 ms
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=6 hlim=64 time=0.270 ms
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=7 hlim=64 time=0.238 ms
16 bytes from fe80::be24:11ff:febb:b7fc%igc0, icmp_seq=8 hlim=64 time=0.263 ms
I am still new to IPv6 and have more questions than awnsers, but should the automatic setup with all of that not automatically route any FE80 addresses to LAN instead of at all sending it out of the WAN interface?

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root@firewall:/var/log/dhcpd # route -6 show fe80::be24:11ff:febb:b7fc
   route to: fe80::be24:11ff:febb:b7fc
destination: default
       mask: default
    gateway: fe80::c203:80ff:fe67:8d43%pppoe0
        fib: 0
  interface: pppoe0
      flags: <UP,GATEWAY,DONE>
 recvpipe  sendpipe  ssthresh  rtt,msec    mtu        weight    expire
       0         0         0         0      1492         1         0

Do I hunt a ghost? Or is there anything I missed?

Please see attached the overview. The default rout for fe80 network points to the WAN interface (pppoe) and not to the LAN interace.

Also what I observed is that the pppoe interface got the physical MAC address of the LAN interface igc0 ... the WAN interface is igc1 and I would have guessed, that the pppoe interface is actually using another one?

So question is? How do I actually get the default route for FE80 to point to LAN? And why is this not the case by default?

Or is this because Telekom is so great to assign a link local address to its gateway and we are communicating over the exact same network externally and internally?

With my knowledge from IPv4 that would be totally confused and not working.

[mooh]

I think that's exactly the right behaviour. Link local addresses are only valid on a certain interface, i.e. that address is reachable only via that interface. This has nothing to do with LAN or WAN. I think what you are complaining about is the default use of the pppoe interface and I agree. Maybe a link local address should not be accepted without a "%interface" postfix. Any automatic selection is guesswork.