Re: [sig-policy] Need to understand logic behind assigning /64 IPv6 addr
On Sep 17, 2011, at 8:44 AM, Mark Tinka wrote:
> On Friday, September 16, 2011 10:07:38 PM Skeeve Stevens
> wrote:
>
>> Thing is… I agree with you when it comes to
>> Interconnects, and so on, where I am much more
>> conservative, using /112's where a lot of people are
>> using much larger (64s, etc).
>
> I've never quite understood why a point-to-point link would
> have anything other than a /126 (I've seen some folks doing
> a /127, a little too risque for me).
>
/127s should be fine if you're so inclined. /64s work well too.
IPv6 does not use the subnet and broadcast addresses like IPv4, so
the reservation of first and last address is unnecessary in IPv6.
In some older stacks, there was an issue where a /127 could have
problems due to a deprecated use of a "unknown" address which
could allow the host on one side of the link to claim both addresses,
but that shouldn't be the case with any up to date implementation.
> We use /112's for BMA LAN's (like among various routers in a
> production network). It's more than we shall ever need on a
> single LAN, but it's not as perverse as a /64, given that we
> manually assign our devices their v6 addresses.
>
You're welcome to do as you wish, but, I see no point in doing so.
It just complicates your administration without providing any
benefit.
> I'm just not sure how many devices you can address on a
> point-to-point link that has only two devices on either end
> of it.
>
Any value of n where 2≤n≤18e+18 if you use a /64.
Any value of n where 2≤n≤65,536 if you use a /112
Any value of n where 2≤n≤4 if you use a /126
and n=2 if you use a /127
Owen