Re: Disabling ip4 and IPV6 on F20RC1

[Pavel Simerda <psimerda redhat com>]

----- Original Message -----
> From: "Bjørn Mork" <bjorn mork no>
> To: "Pavel Simerda" <psimerda redhat com>
> Both link local and global addresses can be manually configured
> in the sense that the interface identifier can be manually configured.

Obviously.

In context of NetworkManager features, static/manual addressing refers to global addresses, configured by the 
user, that are added to the network interface, while link-local adresses are configured by the kernel. See 
below.

> I don't know anything about OpenVZ,

Works pretty well.

“venet devices are not fully IPv6 compliant, but still works if you statically assign IPv6 addresses. They do 
not properly support MAC addresses and consequently link local addresses and can not play nice with neighbor 
discovery or router advertisements, router discovery, or auto-conf.”

(source: http://openvz.org/IPv6)

OpenVZ venet interfaces work as expected, you can't distinguish them from compliant IPv6 on Ethernet from the 
network. Therefore it's 100% interoperable but not compliant. That sounds like the standard which is there to 
ensure interoperability imposes restrictions that are not necessary for a specific case. Of course OpenVZ 
could add a pair of link-local adresses for each network but they would never be used in practice.

> but ppp links do of course distinguish between link-local and global addresses.

I don't have an IPv6-enabled PPP connection right at hand but I think I've seen a working setup without one. 
But I'm not going to set up one right now, so there's no point in arguing over that. I guess the simple fact 
that you technically don't need link-local addresses for global routing doesn't help you.

> The Linux kernel does of course also distinguish between link-local and
> global addresses, regardless of interface type.

Obviously.

> Link local and global addresses are not interchangable.

Obviously.

> > There's actually no reason you would need link-local addresses for
> > static configuration.
>
> I hear you say that.  You are wrong.

It's actually trivial to test that by either:

a) Simply configuring global addresses using iproute and using tools like ping to communicate over the 
network.

b) Actually learning about the protocols and/or watching packet flow using tcpdump or a similar tool.

IPv6 routing works exactly the same as IPv4 routing except that ARP packets for the first hop resolution are 
replaced with ICMP packets. When communicating over global IPv6 addresses, you never need to use a link-local 
one. If you can challenge that on technical ground, I'm buying you a dinner.

----- Original Message -----
> From: "Bjørn Mork" <bjorn mork no>
> To: "Pavel Simerda" <psimerda redhat com>
> Cc: "Tore Anderson" <tore fud no>, networkmanager-list gnome org, "Dan Winship" <danw redhat com>
> Sent: Tuesday, December 17, 2013 3:20:10 PM
> Subject: Re: Disabling ip4 and IPV6 on F20RC1
> > But unfortunately we need to be a little bit careful about the theory
> > written down on paper and the actual needs. Linux has the long history
> > of allowing more than just blind following of what's written down.
>
> I was writing a longer reply to this, but I think I'd better not.  This
> is just stupid.

Please don't call something stupid just because you didn't get it. I'm here to answer any questions if needed.

Cheers,

Pavel