Fedora IPv6 testing and improvements - request for ideas

Peter Robinson pbrobinson at gmail.com
Thu Oct 29 19:35:00 UTC 2015


On Thu, Oct 29, 2015 at 3:15 PM, Pavel Simerda <psimerda at redhat.com> wrote:
> Hi all,
>
> I am writing to Fedora development mailing lists to get opinions
> and ideas regarding our project on improving IPv6 support in
> Fedora across its components.
>
> https://fedoraproject.org/wiki/QA/Networking

In the above page:
* Network configuration: I see NetworkManager in there but nothing
about systemd-networkd
* Other: firewalld including zones and other such configurations (you
mention iptables)

> Most prominent subpages:
>
>  * https://fedoraproject.org/wiki/QA/Networking/Test_environment

In this section I see "IPv6 node" but nothing that covers a IPv6 only
routed network with IPv6 to IPv4 gateway ie it runs v6 only internally
but uses 6 to 4 services for legacy services.

>  * https://fedoraproject.org/wiki/QA/Networking/Client_software

Again nothing about a native IPv6 only network with a gateway that
supports 6to4 for legacy services outside the network.

What about a iOS9 style preferring of IPv6 over IPv4 in the general
desktop. In the iOS9 case they do network measurements and favour IPv6
bydefault, and if it's going to be faster but fail back quickly if
it's not, how would we deal with this?

>  * https://fedoraproject.org/wiki/QA/Networking/Server_software

Nothing in here about:
* IPv6 services RA, dhcp6, 6 to 4 proxies, 4 to 6 proxies and other
such transition servers
* what about VPN services like a IPv6 only network connecting to a
dual stack VPN, or a IPv4 only VPN or a number of combinations there
of IE interfaces that are v6 only and ones that are v4 only. What
happens with routing then if there's other 6 to 4 services in play?
* Load balancers ie like facebook uses to bridge external dual stack
to IPv6 only internal services, or providing IPv6 externally to
present internal v4 services externally to v6

There's also nothing I can see from a quick read about offload
engines. A lot of 10Gb+ network interfaces have offloads for generic
IP, TCP, other acceleration to enable to do line speed 10+gb on IPv4,
we obviously want acceleration because IPv6 headers are larger and
hence take up more memory. There's toolkits like dpgk (
http://dpdk.org ) for acceleration of packets across large bandwidth
interfaces but I don't see any mention of that or network IO
virtualisation/offload.

Facebook and others have been testing these sorts of things:

https://code.facebook.com/posts/1123882380960538/linux-ipv6-improvement-routing-cache-on-demand/
https://code.facebook.com/posts/938078729581886/improving-the-linux-kernel-with-upstream-contributions/

Along these lines also I see nothing about Open vSwitch and SND
encapsulation protocols testing such as vxlan, GRE, GENEVE etc

> During the first phase we are interested in getting feedback on
> testing methods and test cases. Any other ideas are of course
> welcome. Even contacts for future collaboration would be great.

A future development would be around 6LoWPAN and the routing protocols
etc for that so we can communicate with IoT devices.

The way I read a lot of the pages above is a "this is how we did it on
IPv4 lets test it on IPv6" rather than a review of how things are
going to change with IPv6, how would I get to a IPv4 site if I'm on a
IPv6 network, visa versa and the whole sets of new use cases that are
appearing as a result of it.

Peter


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