[141566] in North American Network Operators' Group
Re: Cogent IPv6
daemon@ATHENA.MIT.EDU (Owen DeLong)
Thu Jun 9 04:36:24 2011
From: Owen DeLong <owen@delong.com>
In-Reply-To: <BANLkTikJjjyy82XEjkesrh_3yaDixqVQNQ@mail.gmail.com>
Date: Thu, 9 Jun 2011 01:32:58 -0700
To: William Herrin <bill@herrin.us>
Cc: "nanog@nanog.org" <nanog@nanog.org>, Kelly Setzer <Kelly.Setzer@wnco.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Jun 8, 2011, at 7:24 PM, William Herrin wrote:
> On Wed, Jun 8, 2011 at 9:58 PM, Kelly Setzer <Kelly.Setzer@wnco.com> wrote:
>> IPv6 newbie alert!
>>
>> I thought the maximum prefix length for IPv6 was 64 bits,
>> so the comment about a v6 /112 for peering vexed me. I
>> have Googled so much that Larry Page called me and
>> asked me to stop.
>>
>> Can someone please point me to a resource that explains
>> how IPv6 subnets larger than 64 bits function and how
>> they would typically be used?
>
> Hi Kelly,
>
> IPv6 netmasks work exactly like IPv4 netmasks. You can even route
> /128's if you want. Two major caveats:
>
> 1. SLAAC (stateless autoconfiguration, the more or less replacement
> for DHCP) only works if the subnet on your LAN is exactly /64. So
> unless you're manually configuring the IPv6 address on every machine
> on your subnet, you're using a /64.
>
You can actually use DHCPv6 to assign addresses to hosts dynamically
on longer than /64 networks.
However, you may have to go to some effort to add DHCPv6 support to
those hosts first.
Owen
