vxlan.rst 3.0 KB

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  1. .. SPDX-License-Identifier: GPL-2.0
  2. ======================================================
  3. Virtual eXtensible Local Area Networking documentation
  4. ======================================================
  5. The VXLAN protocol is a tunnelling protocol designed to solve the
  6. problem of limited VLAN IDs (4096) in IEEE 802.1q. With VXLAN the
  7. size of the identifier is expanded to 24 bits (16777216).
  8. VXLAN is described by IETF RFC 7348, and has been implemented by a
  9. number of vendors. The protocol runs over UDP using a single
  10. destination port. This document describes the Linux kernel tunnel
  11. device, there is also a separate implementation of VXLAN for
  12. Openvswitch.
  13. Unlike most tunnels, a VXLAN is a 1 to N network, not just point to
  14. point. A VXLAN device can learn the IP address of the other endpoint
  15. either dynamically in a manner similar to a learning bridge, or make
  16. use of statically-configured forwarding entries.
  17. The management of vxlan is done in a manner similar to its two closest
  18. neighbors GRE and VLAN. Configuring VXLAN requires the version of
  19. iproute2 that matches the kernel release where VXLAN was first merged
  20. upstream.
  21. 1. Create vxlan device::
  22. # ip link add vxlan0 type vxlan id 42 group 239.1.1.1 dev eth1 dstport 4789
  23. This creates a new device named vxlan0. The device uses the multicast
  24. group 239.1.1.1 over eth1 to handle traffic for which there is no
  25. entry in the forwarding table. The destination port number is set to
  26. the IANA-assigned value of 4789. The Linux implementation of VXLAN
  27. pre-dates the IANA's selection of a standard destination port number
  28. and uses the Linux-selected value by default to maintain backwards
  29. compatibility.
  30. 2. Delete vxlan device::
  31. # ip link delete vxlan0
  32. 3. Show vxlan info::
  33. # ip -d link show vxlan0
  34. It is possible to create, destroy and display the vxlan
  35. forwarding table using the new bridge command.
  36. 1. Create forwarding table entry::
  37. # bridge fdb add to 00:17:42:8a:b4:05 dst 192.19.0.2 dev vxlan0
  38. 2. Delete forwarding table entry::
  39. # bridge fdb delete 00:17:42:8a:b4:05 dev vxlan0
  40. 3. Show forwarding table::
  41. # bridge fdb show dev vxlan0
  42. The following NIC features may indicate support for UDP tunnel-related
  43. offloads (most commonly VXLAN features, but support for a particular
  44. encapsulation protocol is NIC specific):
  45. - `tx-udp_tnl-segmentation`
  46. - `tx-udp_tnl-csum-segmentation`
  47. ability to perform TCP segmentation offload of UDP encapsulated frames
  48. - `rx-udp_tunnel-port-offload`
  49. receive side parsing of UDP encapsulated frames which allows NICs to
  50. perform protocol-aware offloads, like checksum validation offload of
  51. inner frames (only needed by NICs without protocol-agnostic offloads)
  52. For devices supporting `rx-udp_tunnel-port-offload` the list of currently
  53. offloaded ports can be interrogated with `ethtool`::
  54. $ ethtool --show-tunnels eth0
  55. Tunnel information for eth0:
  56. UDP port table 0:
  57. Size: 4
  58. Types: vxlan
  59. No entries
  60. UDP port table 1:
  61. Size: 4
  62. Types: geneve, vxlan-gpe
  63. Entries (1):
  64. port 1230, vxlan-gpe