[pve-devel] [PATCH] fabrics: fix IPv6 section

[Hannes Duerr]

reads very well.

Reviewed-by: Hannes Duerr <h.duerr at proxmox.com>

On 7/18/25 10:08, Gabriel Goller wrote:
> Fix the IPv6 section, now we don't enable IPv6 forwarding anymore, but
> the user has to manually enable it. Also add some more info on how to do
> it.
>
> When applying the last fabrics series, this patch was missed, so update
> the old docs to the latest version.
>
> Signed-off-by: Gabriel Goller <g.goller at proxmox.com>
> ---
>   pvesdn.adoc | 33 +++++++++++++++++++++++++--------
>   1 file changed, 25 insertions(+), 8 deletions(-)
>
> diff --git a/pvesdn.adoc b/pvesdn.adoc
> index ab3caebd2519..0826b335badc 100644
> --- a/pvesdn.adoc
> +++ b/pvesdn.adoc
> @@ -575,7 +575,7 @@ Loopback Prefix
>   ^^^^^^^^^^^^^^^
>   
>   You can specify a CIDR network range (e.g., 192.0.2.0/24) as a loopback prefix
> -for the fabric.  When configured, the system will automatically verify that all
> +for the fabric. When configured, the system will automatically verify that all
>   router-IDs are contained within this prefix. This ensures consistency in your
>   addressing scheme and helps prevent addressing conflicts or errors.
>   
> @@ -599,6 +599,28 @@ ensures that traffic originates from the local dummy interface's IP address
>   rather than from the physical interface. This provides consistent routing
>   behavior and proper source address selection throughout the fabric.
>   
> +[[pvesdn_config_fabrics_ipv6]]
> +Notes on IPv6
> +^^^^^^^^^^^^^
> +
> +IPv6 is currently only usable on OpenFabric fabrics. These IPv6 Fabrics need
> +global IPv6 forwarding enabled on all nodes contained in the fabric. Without
> +IPv6 forwarding, non-full-mesh fabrics won't work because the transit nodes
> +don't forward packets to the outer nodes. Currently there isn't an easy way to
> +enable IPv6 forwarding per-interface like with IPv4, so it has to be enabled
> +globally. This can be accomplished by appending this line:
> +
> +----
> +post-up sysctl -w net.ipv6.conf.all.forwarding=1
> +----
> +
> +to a fabric interface in the `/etc/network/interfaces` file. This will enable
> +IPv6 forwarding globally once that interface comes up. Note that this affects
> +how your interfaces handle automatic IPv6 setup (SLAAC), Neighbour
> +Advertisements, Router Solicitations, and Router Advertisements. More details
> +here: https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt under
> +`net.ipv6.conf.all.forwarding`.
> +
>   [[pvesdn_openfabric]]
>   OpenFabric
>   ~~~~~~~~~~
> @@ -623,13 +645,8 @@ all router-IDs in the fabric are contained within this prefix.
>   IPv6 Prefix:: IPv6 CIDR network range (e.g., 2001:db8::/64) used to verify that
>   all router-IDs in the fabric are contained within this prefix.
>   
> -WARNING: This will turn on IPv6 forwarding for all interfaces on all nodes.
> -IPv6 forwarding doesn't have a per-interface switch, it must be turned on
> -globally. This affects how your interfaces handle automatic IPv6 setup (SLAAC),
> -Neighbour Advertisements, Router Solicitations, and Router Advertisements. More
> -details here:
> -https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt under
> -`net.ipv6.conf.all.forwarding`.
> +WARNING: For IPv6 fabrics to work, global forwarding needs to be enabled on all
> +nodes. Check xref:pvesdn_config_fabrics_ipv6[Notes on IPv6] for how to do it and additional info.
>   
>   Hello Interval:: Controls how frequently (in seconds) hello packets are sent to
>   discover and maintain connections with neighboring nodes. Lower values detect