Re: Enterprise Analysis DSTM Issue

[Stig Venaas <Stig.Venaas@uninett.no>]

On Wed, Aug 10, 2005 at 06:31:45PM +0300, Pekka Savola wrote:
[...]
> On Wed, 10 Aug 2005, Tim Chown wrote:
> >We can state in the analysis that we need
> >a protocol for that scenario (#3 of RFC4057) that supports:
> >
> > a) v4-in-v6 tunnels
> > b) automatic set up of v4-in-v6 tunnels when the host
> >    doesn't have v4 address and an app wants to create a v4 socket
> > c) authentication for tunnel setup
> 
> OK, this is good.  Let's try to separate b) into three:
> 
>   b1) automatic set up of v4-in-v6 tunnels
> 
>   b2) automatic set up of v4-in-v6 tunnels when the host
>      doesn't have v4 address
> 
>   b3) automatic set up of v4-in-v6 tunnels when the host
>      doesn't have v4 address and an app wants to create a v4 socket
> 
> What are the requirements, exactly?

If you have sufficient amount of IPv4 addresses you could probably
use several mechanisms where you set up tunnels and assign addresses
to every client in the network. As I understand it, DSTM is in
particularly useful when you have hosts that rarely need IPv4
communications, you have enough IPv4 addresses to serve the hosts
using IPv4 at any given time, but not for all the IPv4-capable
hosts simultaneously. Hence the idea of being triggered by apps
trying to use IPv4 (e.g. creation of v4 socket).

I'm not sure b2 makes sense above. You could automatic setup
v4-in-v6 tunnel when hosts boots provided you have enough IPv4
addresses. However, I think IPv6-only core only makes sense if
IPv4 is rarely used. In that case it makes sense to have tunneling
state only when needed. And as I said above, this may also make
sense if you have lack of addresses. So the tunnel setup and the
assignment of IPv4 address should only be done when needed. One
way of detecting need, is request an IPv4 socket.

I think several networks could manage with little IPv4 traffic
already today. In particular if you have dual-stack mailservers,
dual-stack web proxies etc. You would only need IPv4 to the
internet when using more rare applications.

There are also some networks today that struggle getting enough
IPv4 addresses for the network infrastructure...

Stig