How to analyze IPv6 issues on Zywall

mwoh

My Zywall is behind a cable modem (home network router) provided by the ISP. The cable modem has hardly any configuration options, but supports IPv6.

If I connect a device directly to the cable modem, it gets an IPv6 address and "everything" works.

The cable modem has the IPv6 prefix 1234:5678:9abc:def00::/56 (IP addresses are to be understood as examples, the prefix is ​​subject to change by the ISP without notice).

I have a Zywall 110 on the cable modem.

####### Zywall WAN1 Configuration #########

The Zywall receives an IPv6 prefix from the cable modem via DHCPv6:

DHCPv6 Prefix Delegation: 1234:5678:9abc:def0::/60

That looks good to me.

# ping6 google.ch -n -c 3
PING google.ch(2a00:1450:4016:80c::2003) 56 data bytes
64 bytes from 2a00:1450:4016:80c::2003: icmp_seq=1 ttl=117 time=31.2 ms
64 bytes from 2a00:1450:4016:80c::2003: icmp_seq=2 ttl=117 time=30.9 ms
64 bytes from 2a00:1450:4016:80c::2003: icmp_seq=3 ttl=117 time=30.8 ms
--- google.ch ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 30.802/30.970/31.207/0.224ms

On the LAN side of the Zywall I have two networks: LAN1 and DMZ.

At first I only care about LAN1.

####### Zywall LAN1 Configuration #########

Under "IPv6 Address Assignment" I assign an IP address for the LAN port.

Address from DHCPv6 Prefix Delegation, Suffix ::1:0:0:0:1/128

Returns address 1234:5678:9abc:def1::1/128

DHCPv6 configuration:

DHCPv6 server

DUID as MAC

DHCPv6 Lease Options: DNS1 and DNS2 on Google DNS Server (This is necessary because my ISP's DNS servers are very slow)

Enable Router Advertisement

Advertised Hosts Get Network Configuration From DHCPv6

Advertised Hosts Get Other Configuration From DHCPv6

Advertised Prefix from DHCPv6 Prefix Delegation:

- Suffix Address ::1/64

- Results in address 1234:5678:9abc:def1::/64

 

 

####### CONNECTED DEVICE (e.g. MACBOOK) ##########

Shown in network preferences (DHCP):

Router: fe80::a2e4:cbff:fe7d:d16d

IP address: 1234:5678:9abc:def1:cf4:8ba5:7a83:9a77

What is striking: no IPv6 DNS servers seem to be transmitted.

Nevertheless, e.g. google.ch can be resolved correctly from the macbook.

What is also noticeable: the IP address displayed by ping6 (1234:5678:9abc:def1:252a:7742:4798:fae4) is not the same as displayed in the system settings of OS-X (1234:5678:9abc:def1: cf4:8ba5:7a83:9a77).

ping6 google.ch -n -c 3
PING6(56=40+8+8 bytes) 1234:5678:9abc:def1:252a:7742:4798:fae4 --> 2a00:1450:4016:80c::2003
--- google.ch ping6 statistics ---
3 packets transmitted, 0 packets received, 100.0% packet loss

ping6 2a00:1450:4016:80c::2003 -n -c 3
PING6(56=40+8+8 bytes) 1234:5678:9abc:def1:252a:7742:4798:fae4 --> 2a00:1450:4016:80c::2003
--- 2a00:1450:4016:80c::2003 ping6 statistics ---
3 packets transmitted, 0 packets received, 100.0% packet loss

I've been working on this issue for a few days now and have read numerous articles from the Zyxel Community. Unfortunately so far without success.

Does anyone have any tips for me on how to further analyze the problem?