interfaces-vxlan - VXLAN extensions for the interfaces(5) file format

Maximilian Wilhelm <max@sdn.clinic> 2025-03-25 interfaces-vxlan(5)

Virtual eXtensible LAN (VXLAN) is an overlay network to carry Layer 2 over an IP network while accommodating a very large number of tenants. It is defined in RFC 7348. Be aware that VXLAN encapsulation adds 50 bytes of overhead to the IP packet header (inner Ethernet header + VXLAN + UDP + IP). This should be taken into consideration when setting up overlay networks, particularly on underlay networks with a conventional 1500 byte MTU. The following options set up VXLAN Tunnel EndPoints (VTEP) interfaces with ifupdown-ng. See https://www.kernel.org/doc/Documentation/networking/vxlan.rst and https://vincent.bernat.ch/en/blog/2017-vxlan-linux for more information.

A VTEP with multiple peers addressed via a multicast group: auto vx_v1001_padcty iface vx_v1001_padcty vxlan-id 655617 vxlan-physdev vlan1001 vxlan-remote-group 225.10.1.1 # hwaddress f2:00:c1:01:10:01 mtu 1560 The same works just fine with IPv6 in the underlay: auto vx_v1400_padcty iface vx_v1400_padcty vxlan-id 917505 vxlan-physdev vlan1400 vxlan-peer-group ff42:1400::1 # hwaddress f2:00:0d:01:14:00 mtu 1560 Note that the underlay must have an MTU of at least 1610 to carry the encapsulated packets of the two VTEPs above. A VTEP with one peer (unicast point-to-point configuration): auto vx_ptp1 iface vx_ptp1 vxlan-id 2342 vxlan-local-ip 192.0.2.42 vxlan-peer-ips 198.51.100.23 # hwaddress f2:00:c1:01:10:01 A VTEP with multiple peers (unicast point-to-multipoint with ingress / head-end replication): auto vx_her iface vx_her vxlan-id 1337 vxlan-local-ip 2001:db8:1::1 vxlan-peer-ips 2001:db8:2::23 2001:db8:3::42 2001:db8:4::84

interfaces-vxlan - VXLAN extensions for the interfaces(5) file format

A VXLAN Virtual Tunnel Endpoint (VTEP) interface must an ID set. All other options are optional. vxlan-idVNIID Denotes the VXLAN Network Identifier (VNI) ID for this interface. This parameter is required for VTEP interfaces. vxlan-physdevinterface Specifies the physical ("underlay") device to use for tunnel endpoint communication. This is required for setups using multicast. vxlan-local-ipaddress Specifies the source IP address to use in outgoing packets. For compatiblity with ifupdown2 vxlan-local-tunnelip is an alias for this parameter. vxlan-peer-ipslistofIPaddresses Specifies the unicast destination IP address(es) to use in outgoing packets when the destination link layer address is not known in the VXLAN device forwarding database. This option can be used to form Point-to-Point as well as Point-to-Multipoint VXLAN tunnels/ overlays depending on how many peer IPs are given. If more than one IP address is given a Point-to-Multipoint overlay is being set up and ingress / head-end replication will be used by the Linux Kernel. This option cannot be used together with vxlan-peer-group option. For compatiblity with ifupdown2 vxlan-remoteip is an alias for this option and for compatibility with previos versions of ifupdown-ng vxlan-remote-ip is an alias for this option, too. vxlan-peer-groupmulticastgroup Specifies the multicast group address to join, requires vxlan-phsydev to be set as well. This parameter cannot be specified in combination with the vxlan-peer-ips parameter. For compatibility with ifupdown2 vxlan-svcnodeip is an alias for this option and for compatibility with previos version of ifupdown-ng vxlan-remote-group is an alias, too. vxlan-learningon/off Specifies if unknown source link layer addresses and IP addresses are entered into the VXLAN device forwarding database. vxlan-ageingseconds Specifies the lifetime in seconds of FDB entries learnt by the kernel. vxlan-dstportport Specifies the UDP destination port of the remote VXLAN tunnel endpoint. The default is 4789.