On 2011-07-13 12:09 , Mikael Abrahamsson wrote:
> On Wed, 13 Jul 2011, Jeroen Massar wrote:
> 
>> Heck, some people pick a /120 for it or whatever they find nice.
>> Configuration wise and counting wise /64 is just handy. And if one day
>> you have multi-access on that link, well, no re-numbering, just enable
>> it.
> 
> That's why /125 is nice for renumbering, and no ND issue.

Yeah, pick whatever you like I would say. Just stay away from actually
putting a /127 on the link. Two /128s works like a charm though as then
subnet anycast is not involved anymore.

>>>> The "ND" issue now lies at the CPE device of the user, who will most
>>>> likely not be able to handle 1GB/s anyway when somebody wants to DDoS
>>>> them off the net...
>>>
>>> No it doesn't, if I am ::1 then if someone sends 10kpps to random values
>>> of ::X:Y:Z:W on that subnet I have to ND all those.
>>
>> There is no subnet, only ::2, the rest you can ignore.
> 
> What should the router do when someone sends a packet to ::3 on that
> subnet? If it's a /64, then it's a subnet with 2^64 active addresses, I
> don't understand how you can call it a non-subnet.

To take this little thing called SixXS as an example, we allocate a /64
per tunnel, but only use <tunnel>::1 (PoP) and <tunnel>::2 (user).

We actually only configure ::1 on the tunnel and route ::2 to the
tunnel, thus effectively two /128's. Thus for everything else there will
be directly an ICMP unreachable. Simple as that.

>> Test it out today and complain to your vendor ;)
> 
> Wow.

What else would you do? :)

Greets,
 Jeroen
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