[AusNOG] IPv6

[Mark Newton]

On 1 Apr 2015, at 5:55 pm, Anthony Bortolotto <a.bortolotto at infinite.net.au> wrote:
> 
> . It is not turned on by default on most customer CPE’s [...]

I beg to differ. IPv6 capable ADSL CPE generally has it enabled by default.

Whether or not it actually does anything depends on whether the ISP's BRAS attempts to negotiate IP6CP during PPP startup (or, conceivably, at some later point).

If it does, IP6CP comes up, then the BRAS does a Radius lookup to work out which /64 it'll use for the PPP link, and SLAAC is used to pick IPv6 addresses for each end. The CPE can then optionally issue a DHCPv6-PD request to get another larger prefix if desired, which will cause the BRAS to do another Radius lookup to see if a Framed-IPv6-Prefix attribute comes back. The CPE will typically assign a /64 from that larger prefix to each of its "internal" network interfaces, which will start sending out RAs to automatically configure IPv6 addresses and default gateways on your hosts.

If no attempt is made to negotiate IP6CP, the IPv6 stack in the CPE remains idle. No harm, no foul.

You should ONLY deploy CPE which has IPv6 features turned on by default at no additional licensing cost, and you should patiently explain to vendors why they should all die in a fire if they don't offer that functionality.  It's 2015, that kind of thing is just. not. on. If your pet vendor doesn't behave themselves, there are plenty of others who will.

If IPv6 is on by default on CPE, then enabling v6 access when you're ready is a relatively painless decision you can make when you're happy to proceed. If it's off by default, you won't get significant take up until you individually contact each and every one of your customers and convince them to turn it on.

Note that IPv6 is enabled by default on every Microsoft Windows host that's been installed since 2008, and it doesn't seem to have done any harm there. If it is harmful in your unique environment, you should be asking what you're doing wrong, rather than wondering how you can turn it off.  

Shorter: If something works just fine literally everywhere in the world except your network, fix your network.

Cheers,

    - mark



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