Subject: Re: ipv6 over PPP
To: None <>
From: Robert Elz <kre@munnari.OZ.AU>
List: tech-net
Date: 09/25/2003 16:37:52
    Date:        Thu, 25 Sep 2003 11:16:18 +0200
    Message-ID:  <>

  | I use IPv6 over PPP here (great ISP).

Is your basic model of operations the same as the one I described?

That is, how do you configure your PPP client?

  | The thing I don't understand is you want your router to act as an
  | auto-configured host WRT the PPP connection, and as a complete router
  | for the rest of the network.


  | Shouldn't the router use a static configuration?

How?   From where does it determine its IPv6 address?   It will only
discover that once it gets the PPP connection.   Sure, while I am only
ever connecting to one destination (as people who use PPP over hard
wired links do) I'm always going to get the same address - or in my
situation I can force that, but I don't want to be constrained to
only dialing one provider - I want to be able to dial anyone, and
if they support IPv6, I want them to tell me what addresses I should

  | Or a routing protocol to handle dynamic links?

A routing protocol is no problem, but that is only effective after
I have addresses that work.

  | I really think this is the point here. You seem to want to push the
  | auto-configuration to a very high level.

Only as high as it works (using totally different mechanisms admittedly)
using IPv4.

With IPv4, all this works using NAT - the ISP tells me what IPv4 address
to use, then my ppp client (router) uses that address, and arranges for
all the other systems to look like they're also using the same address.

Of course, I could do NAT for IPv6, and do everything the same way, but
much of the point of IPv6 is supposed to be to avoid that.   Hence, I
want something for IPv6 that gives equivalent functionality.
  | I don't think a setup where you have a mobile setup connecting randomly
  | to several ISPs concurrently is reasonable.

Why?    As it happens, "concurrently" I don't need - just serially,
but I can't think of any particularly good reason I shouldn't just
be able to use several at once.

  | If the network is mobile,
  | you'll have a default route to the link you're connected to, and if it
  | is only about having multiple links, then you have to go with a routing
  | protocol.

For me it isn't about either at the minute - the network is 'mobile'
in the sense that it can connect to the topology at different points.
Geographically it is quite fixed in place however (not that that should
make a difference to anything - since the phone system (POTS) allows
anyone to connect to anywhere from anywhere, possibly except from on
planes, the attachment point can appear fixed, even if the system is
moving rapidly - or for the same reason, the attachment point can vary
wildly, even though the system is bolted to a large slab of concrete).