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1.. SPDX-License-Identifier: GPL-2.02 3======================================================4Virtual eXtensible Local Area Networking documentation5======================================================6 7The VXLAN protocol is a tunnelling protocol designed to solve the8problem of limited VLAN IDs (4096) in IEEE 802.1q. With VXLAN the9size of the identifier is expanded to 24 bits (16777216).10 11VXLAN is described by IETF RFC 7348, and has been implemented by a12number of vendors. The protocol runs over UDP using a single13destination port. This document describes the Linux kernel tunnel14device, there is also a separate implementation of VXLAN for15Openvswitch.16 17Unlike most tunnels, a VXLAN is a 1 to N network, not just point to18point. A VXLAN device can learn the IP address of the other endpoint19either dynamically in a manner similar to a learning bridge, or make20use of statically-configured forwarding entries.21 22The management of vxlan is done in a manner similar to its two closest23neighbors GRE and VLAN. Configuring VXLAN requires the version of24iproute2 that matches the kernel release where VXLAN was first merged25upstream.26 271. Create vxlan device::28 29 # ip link add vxlan0 type vxlan id 42 group 239.1.1.1 dev eth1 dstport 478930 31This creates a new device named vxlan0. The device uses the multicast32group 239.1.1.1 over eth1 to handle traffic for which there is no33entry in the forwarding table. The destination port number is set to34the IANA-assigned value of 4789. The Linux implementation of VXLAN35pre-dates the IANA's selection of a standard destination port number36and uses the Linux-selected value by default to maintain backwards37compatibility.38 392. Delete vxlan device::40 41 # ip link delete vxlan042 433. Show vxlan info::44 45 # ip -d link show vxlan046 47It is possible to create, destroy and display the vxlan48forwarding table using the new bridge command.49 501. Create forwarding table entry::51 52 # bridge fdb add to 00:17:42:8a:b4:05 dst 192.19.0.2 dev vxlan053 542. Delete forwarding table entry::55 56 # bridge fdb delete 00:17:42:8a:b4:05 dev vxlan057 583. Show forwarding table::59 60 # bridge fdb show dev vxlan061 62The following NIC features may indicate support for UDP tunnel-related63offloads (most commonly VXLAN features, but support for a particular64encapsulation protocol is NIC specific):65 66 - `tx-udp_tnl-segmentation`67 - `tx-udp_tnl-csum-segmentation`68 ability to perform TCP segmentation offload of UDP encapsulated frames69 70 - `rx-udp_tunnel-port-offload`71 receive side parsing of UDP encapsulated frames which allows NICs to72 perform protocol-aware offloads, like checksum validation offload of73 inner frames (only needed by NICs without protocol-agnostic offloads)74 75For devices supporting `rx-udp_tunnel-port-offload` the list of currently76offloaded ports can be interrogated with `ethtool`::77 78 $ ethtool --show-tunnels eth079 Tunnel information for eth0:80 UDP port table 0:81 Size: 482 Types: vxlan83 No entries84 UDP port table 1:85 Size: 486 Types: geneve, vxlan-gpe87 Entries (1):88 port 1230, vxlan-gpe89