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Using debian stretch and I think that my link provider send me a prefix /56 (at least it is what they told me).

Using RA I can use ipv6, but using another ip within prefix I doesn't work. Let me explain my tests:

prefix 2804:431:8840:3000::/56

ip -6 a l

inet6 2804:431:8840:3000::1/56 scope global 
valid_lft forever preferred_lft forever
inet6 fe80::52e5:49ff:fe30:492c/64 scope link 
valid_lft forever preferred_lft forever

ip -6 r l

2804:431:8840:3000::/56 dev wan1 proto kernel metric 256  pref medium
2804:431:8840:3000::/56 via fe80::1272:23ff:fe88:8b1b dev wan1 metric 1024  pref medium
fe80::/64 dev wan1 proto kernel metric 256  pref medium
default via fe80::1272:23ff:fe88:8b1b dev wan1 metric 1024  pref medium

ping6 -c1 registro.br

PING registro.br(registro.br (2001:12ff:0:2::3)) 56 data bytes
64 bytes from registro.br (2001:12ff:0:2::3): icmp_seq=1 ttl=54 time=5.33 ms

so far so good.

Now if I change ip6 to another ip within prefix it does not work...

ip -6 a l

wan1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
inet6 2804:431:8840:300**1**::1/56 scope global  
valid_lft forever preferred_lft forever  
inet6 fe80::52e5:49ff:fe30:492c/64 scope link   
valid_lft forever preferred_lft forever  

ip -6 r l

2804:431:8840:3000::/56 dev wan1 proto kernel metric 256  pref medium  
2804:431:8840:3000::/56 via fe80::1272:23ff:fe88:8b1b dev wan1 metric 1024  pref medium  
fe80::/64 dev wan1 proto kernel metric 256  pref medium   
default via fe80::1272:23ff:fe88:8b1b dev wan1 metric 1024 pref medium  

ping6 -c1 registro.br

PING registro.br(registro.br (2001:12ff:0:2::3)) 56 data bytes

--- registro.br ping statistics --- 1 packets transmitted, 0 received, 100% packet loss, time 0ms

Am I doing something wrong????

I teste with

2804:431:8840:3000::1/64 it works

2804:431:8840:3000:ffff:ffff:ffff:fff/64 it works

2804:431:8840:3000::1/56 it works

Ahh another spec

radvdump gives me:

    interface wan1
    {
    AdvSendAdvert on;
    # Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump
    AdvManagedFlag off;
    AdvOtherConfigFlag on;
    AdvReachableTime 0;
    AdvRetransTimer 0;
    AdvCurHopLimit 64;
    AdvDefaultLifetime 180;
    AdvHomeAgentFlag off;
    AdvDefaultPreference medium;
    AdvLinkMTU 1500;
    AdvSourceLLAddress on;

    prefix 2804:431:8840:3000::/64
    {
            AdvValidLifetime 259200;
            AdvPreferredLifetime 172800;
            AdvOnLink on;
            AdvAutonomous on;
            AdvRouterAddr off;
    }; # End of prefix definition


    route 2804:431:8840:3000::/56
    {
            AdvRoutePreference high;
            AdvRouteLifetime 259200;
    }; # End of route definition

    RDNSS fe80::1272:23ff:fe88:8b1b
    {
            AdvRDNSSLifetime 1200;
    }; # End of RDNSS definition


    DNSSL br
    {
            AdvDNSSLLifetime 1200;
    }; # End of DNSSL definition
  • which address you set it does not work? – AtomiX84 Jan 10 at 13:07
  • Hy any address that is not whithin 2804:431:8840:3000::/64 works.. speeking w/ Telefonica who is my provider they told me that I could only use the first /64 block, but I buy a /56 from tham... it is a mess this provider......8-( – Paulo Ricardo Bruck Jan 11 at 15:33
5

IPv6 auto configuration (which is used by most devices) only works with a /64 on the LAN. Using any other size will indeed not work.

The reason you get a /56 is so that you can have multiple /64 LANs if you want. For example a home LAN, an office LAN, a home automation LAN, an extra strict LAN for the kids etc etc. With a /56 you have enough address space to configure 256 LANs.

If you just want to use one LAN, pick a /64 that you like (anything between 2804:431:8840:3000::/64 and 2804:431:8840:30ff::/64) and configure that.

1

Thanks for response

Yesterday talking w/ a technician from vivo fibra/telefonica he explain that they only delivery a /64 for their clients , but when I bought the link I ask for a /56 and them conffirmed that I would receive a /56... Unfortunately here they do not keep their word......

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