[plug] IPv6 revisited

[Adrian Woodley]

G'day Andrew,

The /64 is used to allocate the IP for the end-point of your PPP 
session; ie one IP from this subnet will be used for your router's ppp0 
and another will be used for the BBA/BRAS interface. This is the 
analogous to the dynamic IPv4 address allocated to your router. This IP 
will change every time you reconnect.

The /56 is a static subnet which is permanently allocated to your 
account. You can either allocate the entire /56 to your LAN 
(4,722,366,482,869,645,213,696 IPs!) or break that subnet up into one or 
more /64s (a mere 18,446,744,073,709,551,616 IPs). This is the analogous 
to the private IP space in IPv4 (ie 192.168.1.0/24). This subnet will 
remain static across reconnections. It is from this range that you 
should allocate IPs to your LAN machines, either via radvd (Neighbour 
Discovery Protocol) or DHCPv6.

I would recommend using a single /64 for your LAN - this leaves you 
options to later on allocate other /64s for networks connected to your 
LAN. For example, I use a second /64 for my laptop, which is routed via 
an IPsec tunnel, giving me IPv6 when I'm away from home. You could even 
do more interesting (paranoid?) things, such as using on /64 for your 
services and another more tightly firewalled /64 for your client machines.

Cheers,

Adrian

On 13/01/14 16:39, Andrew Cooks wrote:
> Hi Plug
>
> I recently implemented IPv4 firewalling on our devices at work and
> Phillip Smith's talk on 'husk' for firewalling both IPv4 and IPv6 at
> the LCA Sysadmin miniconf [1] reminded me again that I really need to
> get a proper grip on IPv6.
>
> So, I followed Adrian Woodley's advice and got an Internode account.
> Internode says I got:
> + A dynamic /64 IPv6 prefix for your PPP session.
> + A static /56 IPv6 prefix for your LAN (if you are using a router
> with Prefix Delegation).
>
> What's the difference between these two prefixes?
>
> Adrian's Plug talk on IPv6 could probably answer some of my questions,
> but is still 'private' on youtube.
>
> Cheers!
>
> a.
>
> 1. http://sysadmin.miniconf.org/presentations14.html#PhillipSmith
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