dhclient6, IA_PD hints, Comcast, and a "pd hint"

[Troy Telford]

On 2013-08-23 02:12:47 +0000, Steven Carr said:

> So the client wouldn't get a /60 subnet mask, you'd need to subnet and
> route the /60 into (16) individual /64s. All IPv6 LANs that end
> clients live on should be /64.
> 
> Steve

Great.  How do I request the /60 to begin with?

> 
> 
> On 23 August 2013 01:26, Troy Telford <ttelford.groups at gmail.com> wrote:
>> I'm using ISC dhclient 4.2.4
>> 
>> Comcast has rolled out native IPv6 in my area.
>> 
>> By default, Comcast assigns a /64 prefix to users. I'm not too happy about
>> this, as I have a few subnets I'd like to keep separated, and you can't do
>> that with a /64 from what I understand.
>> 
>> According to the thread at:
>> http://forums.comcast.com/t5/Home-Networking-Router-WiFi/IPv6-prefix-size-and-home-routing/td-p/1495933 
>> 
>> 
>> Comcast will provide a /60 if the DHCP client requests it in IA_PD. (I'm
>> less familiar with the details of what that actually means, so bear with
>> me).
>> 
>> The instructions given by Comcast are for Cisco iOS, and are something along
>> the lines of:
>> interface GigabitEthernet0/0
>> description Comcast Public
>> ipv6 address dhcp
>> ipv6 enable
>> ipv6 dhcp client pd hint ::/60
>> ipv6 dhcp client pd prefix-from-Comcast
>> ipv6 traffic-filter ipv6_inbound in
>> 
>> The same thread has working configurations for wide-dhcpv6-client (the
>> bottom of the thread), where the prefix size is set by:
>> 
>> id-assoc pd 1 {
>> prefix ::/60 infinity
>> 
>> I've been unable to find any documentation that describes how to configure
>> ISC dhclient to request a prefix size of /60.  (I can only find references
>> to 'dhclient -6 -P ethxyz' - which results in a /64 being assigned.
>> 
>> Does anybody know how to configure dhclient to request a /60 instead of
>> letting the server use its default of /64?
>> 
>> It'd be nice to know and have documented (and easy to find), as Comcast is
>> in the process of deploying IPv6 across their network. I'm sure I'm not the
>> only or last person who will ask to be able to subnet my IPv6 network.
>> 
>> Thanks.
>> --
>> Troy Telford
>> 
>> 
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-- 
Troy Telford