Re: [PATCH perl-rs 3/4] fabrics: openfabric: enable force_forwarding for ipv6 transit traffic

[Gabriel Goller <g.goller@proxmox.com>]

On 01.06.2026 17:15, Lukas Sichert wrote:
> In a non-full-mesh OpenFabric setup, nodes may need to relay traffic
> between peers that are not directly connected. This requires forwarding
> ipv6 packets between fabric bridges. With the addition of
> 'force_forwarding' to the Linux kernel, this can be done without
> enabling 'all.forwarding', which disables Router Advertisements.
> 
> Configure fabric bridges with the required 'post-up'/'post-down'
> commands to enable 'force_forwarding'.
> 
> Signed-off-by: Lukas Sichert <l.sichert@proxmox.com>
> ---
>  pve-rs/src/bindings/sdn/fabrics.rs | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/pve-rs/src/bindings/sdn/fabrics.rs b/pve-rs/src/bindings/sdn/fabrics.rs
> index f96b6b1..785b537 100644
> --- a/pve-rs/src/bindings/sdn/fabrics.rs
> +++ b/pve-rs/src/bindings/sdn/fabrics.rs
> @@ -596,6 +596,16 @@ pub mod pve_rs_sdn_fabrics {
>              writeln!(interface, "\tlink-type {link_type}")?;
>          }
>          writeln!(interface, "\tip-forward 1")?;
> +        if cidr.is_ipv6() {
> +            writeln!(
> +                interface,
> +                "\tpost-up echo 1 > /proc/sys/net/ipv6/conf/{name}/force_forwarding"
> +            )?;
> +            writeln!(
> +                interface,
> +                "\tpost-down echo 0 > /proc/sys/net/ipv6/conf/{name}/force_forwarding"
> +            )?;
> +        }
>  
>          Ok(interface)
>      }

The bgp fabric also needs force_forwarding AFAIK. @Hannes?

Also I just noticed on the bgp fabric we put ipv6 addresses in ifupdown2 inet
blocks (instead of inet6) -- shouldn't cause any problems though.