Re: About IPv6 private address

[Remi Denis-Courmont <rdenis@simphalempin.com>]

On Mon, 04 Feb 2008 10:59:57 +0800, blue <susan.lan@zyxel.com.tw> wrote:

> I want to ask if there's any reserved private IPv6 address? I know

> RFC4193 has defined Unique Local IPv6 Unicast Addresses, which is used

> to replace deprecated site-local address. However, in user's

> perspective, a device will need a well-known address, such as

> 192.168.1.1 in IPv4, for a customer to connect to without any

> configuration. In RFC 4193, the address' "global ID" is generated

> randomly, and the address could not be known in advance.

> 

> After examing all the special purposed IPv6 address, I could not find

> one for this kind of purpose.



In principle, fixed link-local address are possible. Though you'd need to

know the interface identifier on the client, which makes this, as you

noted, not very workable a solution.



I note that this, in any case, can only work for a gateway device. Any

other IP-based appliance (networked printer, networked Hi-Fi, networked

toast-maker) can anyway not use a fixed address, and has to resort to

multicast discovery.



So... in the gateway case, you could probably use a fixed local DNS name

provided by the router DNS cache, that resolves to the ULA of the router.

This means the router needs to have local DNS caching server. Or then, as

already proposed, you can use a fixed ULA, but that kind sucks as it kills

the whole idea UNIQUENESS of ULA.



-- 

Rémi Denis-Courmont

http://www.remlab.net