Re: [PATCH network] sdn: vxlan: always set local tunnel IP

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

On 02.07.2026 16:33, Gabriel Goller wrote:
> Frr 10.6 changed the evpn advertise-all-vni handling and no longer
> falls back to the BGP router-id to derive the local vtep address for
> vxlan interfaces without an explicit local tunnel IP.
> 
> This breaks setups where an evpn controller is used together with a
> vxlan zone to get plain L2VNIs. In that setup, the vxlan zone creates
> the linux vxlan devices, while the evpn controller advertises them
> via frr's advertise-all-vni. Without a local vxlan tunnel IP on the
> interface, frr 10.6 cannot reliably determine the local vtep address and
> the VNI is not advertised/handled correctly.
> 
> Explicitly emit the ifupdown2 `vxlan-local-tunnelip` stanza for vxlan
> zones, using the local peer/fabric underlay address that is already
> determined while generating the zone configuration. Fail generation if
> no local tunnel IP can be determined, since generating such an interface
> would result in a broken evpn/vxlan setup with current frr.
> 
> evpn zones already emit `vxlan-local-tunnelip` for their vxlan devices
> when the local vtep address is known.
> 
> Fixes: #7766.
> Signed-off-by: Gabriel Goller <g.goller@proxmox.com>
> ---
>  src/PVE/Network/SDN/Zones/VxlanPlugin.pm                   | 4 ++++
>  src/test/zones/vxlan/basic/expected_sdn_interfaces         | 1 +
>  src/test/zones/vxlan/ipv6/expected_sdn_interfaces          | 1 +
>  src/test/zones/vxlan/vlanawarevnet/expected_sdn_interfaces | 1 +
>  src/test/zones/vxlan/vxlanport/expected_sdn_interfaces     | 1 +
>  5 files changed, 8 insertions(+)
> 
> diff --git a/src/PVE/Network/SDN/Zones/VxlanPlugin.pm b/src/PVE/Network/SDN/Zones/VxlanPlugin.pm
> index a40826153d9c..b1bd56db6ea9 100644
> --- a/src/PVE/Network/SDN/Zones/VxlanPlugin.pm
> +++ b/src/PVE/Network/SDN/Zones/VxlanPlugin.pm
> @@ -117,6 +117,9 @@ sub generate_sdn_config {
>          die "neither peers nor fabric configured for VXLAN zone $plugin_config->{id}";
>      }
>  
> +    die "could not determine local tunnel IP for VXLAN zone $zoneid"
> +        if !$ifaceip;
> +
>      my $mtu = 1450;
>      if ($iface) {
>          $mtu = $interfaces_config->{$iface}->{mtu} - 50 if $interfaces_config->{$iface}->{mtu};
> @@ -126,6 +129,7 @@ sub generate_sdn_config {
>      #vxlan interface
>      my @iface_config = ();
>      push @iface_config, "vxlan-id $tag";
> +    push @iface_config, "vxlan-local-tunnelip $ifaceip";
>  
>      for my $address (sort @peers) {
>          next if $address eq $ifaceip;

Just for completeness sake:
If we do not have the `$ifaceip` for some reason, the local ip will be inserted
into the vxlan-remote-ip list, which breaks the vxlan setup completely. So we
should be safe to assume here that any working setup has an `$ifaceip`.

Still we can either backport the frr pr, merge this, or pull in both patches.

> diff --git a/src/test/zones/vxlan/basic/expected_sdn_interfaces b/src/test/zones/vxlan/basic/expected_sdn_interfaces
> index 7b73c3e3ca60..ed6869dfa9e6 100644
> --- a/src/test/zones/vxlan/basic/expected_sdn_interfaces
> +++ b/src/test/zones/vxlan/basic/expected_sdn_interfaces
> @@ -10,6 +10,7 @@ iface myvnet
>  auto vxlan_myvnet
>  iface vxlan_myvnet
>  	vxlan-id 100
> +	vxlan-local-tunnelip 192.168.0.1
>  	vxlan_remoteip 192.168.0.2
>  	vxlan_remoteip 192.168.0.3
>  	mtu 1450
> diff --git a/src/test/zones/vxlan/ipv6/expected_sdn_interfaces b/src/test/zones/vxlan/ipv6/expected_sdn_interfaces
> index 032ab991826c..14354f61f923 100644
> --- a/src/test/zones/vxlan/ipv6/expected_sdn_interfaces
> +++ b/src/test/zones/vxlan/ipv6/expected_sdn_interfaces
> @@ -10,6 +10,7 @@ iface myvnet
>  auto vxlan_myvnet
>  iface vxlan_myvnet
>  	vxlan-id 100
> +	vxlan-local-tunnelip 2a08:2200:100:1::10
>  	vxlan_remoteip 2a08:2200:100:1::11
>  	vxlan_remoteip 2a08:2200:100:1::12
>  	mtu 1450
> diff --git a/src/test/zones/vxlan/vlanawarevnet/expected_sdn_interfaces b/src/test/zones/vxlan/vlanawarevnet/expected_sdn_interfaces
> index 55cdf9cb8887..e6331d2e3807 100644
> --- a/src/test/zones/vxlan/vlanawarevnet/expected_sdn_interfaces
> +++ b/src/test/zones/vxlan/vlanawarevnet/expected_sdn_interfaces
> @@ -12,6 +12,7 @@ iface myvnet
>  auto vxlan_myvnet
>  iface vxlan_myvnet
>  	vxlan-id 100
> +	vxlan-local-tunnelip 192.168.0.1
>  	vxlan_remoteip 192.168.0.2
>  	vxlan_remoteip 192.168.0.3
>  	mtu 1450
> diff --git a/src/test/zones/vxlan/vxlanport/expected_sdn_interfaces b/src/test/zones/vxlan/vxlanport/expected_sdn_interfaces
> index 572550a438e7..a3147b66a9c1 100644
> --- a/src/test/zones/vxlan/vxlanport/expected_sdn_interfaces
> +++ b/src/test/zones/vxlan/vxlanport/expected_sdn_interfaces
> @@ -10,6 +10,7 @@ iface myvnet
>  auto vxlan_myvnet
>  iface vxlan_myvnet
>  	vxlan-id 100
> +	vxlan-local-tunnelip 192.168.0.1
>  	vxlan_remoteip 192.168.0.2
>  	vxlan_remoteip 192.168.0.3
>  	vxlan-port 6000
> -- 
> 2.47.3
> 
> 
> 
> 
>