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