diff options
Diffstat (limited to 'docs/interfaces/vxlan.rst')
| -rw-r--r-- | docs/interfaces/vxlan.rst | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/docs/interfaces/vxlan.rst b/docs/interfaces/vxlan.rst new file mode 100644 index 00000000..4755b7c4 --- /dev/null +++ b/docs/interfaces/vxlan.rst @@ -0,0 +1,283 @@ +VXLAN +----- + +VXLAN is an overlaying Ethernet over IP protocol. +It is described in RFC7348_. + +If configuring VXLAN in a VyOS virtual machine, ensure that MAC spoofing +(Hyper-V) or Forged Transmits (ESX) are permitted, otherwise forwarded frames +may be blocked by the hypervisor. + +Multicast VXLAN +^^^^^^^^^^^^^^^^ + +Example Topology: + +PC4 - Leaf2 - Spine1 - Leaf3 - PC5 + +PC4 has IP 10.0.0.4/24 and PC5 has IP 10.0.0.5/24, so they believe they are in +the same broadcast domain. + +Let's assume PC4 on Leaf2 wants to ping PC5 on Leaf3. Instead of setting Leaf3 +as our remote end manually, Leaf2 encapsulates the packet into a UDP-packet and +sends it to its designated multicast-address via Spine1. When Spine1 receives +this packet it forwards it to all other Leafs who has joined the same +multicast-group, in this case Leaf3. When Leaf3 receives the packet it forwards +it, while at the same time learning that PC4 is reachable behind Leaf2, because +the encapsulated packet had Leaf2's IP-address set as source IP. + +PC5 receives the ping echo, responds with an echo reply that Leaf3 receives and +this time forwards to Leaf2's unicast address directly because it learned the +location of PC4 above. When Leaf2 receives the echo reply from PC5 it sees that +it came from Leaf3 and so remembers that PC5 is reachable via Leaf3. + +Thanks to this discovery, any subsequent traffic between PC4 and PC5 will not +be using the multicast-address between the Leafs as they both know behind which +Leaf the PCs are connected. This saves traffic as less multicast packets sent +reduces the load on the network, which improves scalability when more Leafs are +added. + +For optimal scalability Multicast shouldn't be used at all, but instead use BGP +to signal all connected devices between leafs. Unfortunately, VyOS does not yet +support this. + +Configuration commands +^^^^^^^^^^^^^^^^^^^^^^ + +.. code-block:: sh + + interfaces + vxlan <vxlan[0-16777215]> + address # IP address of the VXLAN interface + bridge-group # Configure a L2 bridge-group + description # Description + group <ipv4> # IPv4 Multicast group address (required) + ip # IPv4 routing options + ipv6 # IPv6 routing options + link <dev> # IP interface for underlay of this vxlan overlay (optional) + mtu # MTU + policy # Policy routing options + remote # Remote address of the VXLAN tunnel, used for PTP instead of multicast + vni <1-16777215> # Virtual Network Identifier (required) + +Configuration Example +^^^^^^^^^^^^^^^^^^^^^ + +The setup is this: + +Leaf2 - Spine1 - Leaf3 + +Spine1 is a Cisco IOS router running version 15.4, Leaf2 and Leaf3 is each a +VyOS router running 1.2. + +This topology was built using GNS3. + +Topology: + +.. code-block:: sh + + Spine1: + fa0/2 towards Leaf2, IP-address: 10.1.2.1/24 + fa0/3 towards Leaf3, IP-address: 10.1.3.1/24 + + Leaf2: + Eth0 towards Spine1, IP-address: 10.1.2.2/24 + Eth1 towards a vlan-aware switch + + Leaf3: + Eth0 towards Spine1, IP-address 10.1.3.3/24 + Eth1 towards a vlan-aware switch + +Spine1 Configuration: + +.. code-block:: sh + + conf t + ip multicast-routing + ! + interface fastethernet0/2 + ip address 10.1.2.1 255.255.255.0 + ip pim sparse-dense-mode + ! + interface fastethernet0/3 + ip address 10.1.3.1 255.255.255.0 + ip pim sparse-dense-mode + ! + router ospf 1 + network 10.0.0.0 0.255.255.255 area 0 + +Multicast-routing is required for the leafs to forward traffic between each +other in a more scalable way. This also requires PIM to be enabled towards the +Leafs so that the Spine can learn what multicast groups each Leaf expect traffic +from. + +Leaf2 configuration: + +.. code-block:: sh + + set interfaces ethernet eth0 address '10.1.2.2/24' + set protocols ospf area 0 network '10.0.0.0/8' + + ! Our first vxlan interface + set interfaces bridge br241 address '172.16.241.1/24' + set interfaces ethernet eth1 vif 241 bridge-group bridge 'br241' + set interfaces vxlan vxlan241 bridge-group bridge 'br241' + set interfaces vxlan vxlan241 group '239.0.0.241' + set interfaces vxlan vxlan241 link 'eth0' + set interfaces vxlan vxlan241 vni '241' + + ! Our seconds vxlan interface + set interfaces bridge br242 address '172.16.242.1/24' + set interfaces ethernet eth1 vif 242 bridge-group bridge 'br242' + set interfaces vxlan vxlan242 bridge-group bridge 'br242' + set interfaces vxlan vxlan242 group '239.0.0.242' + set interfaces vxlan vxlan242 link 'eth0' + set interfaces vxlan vxlan242 vni '242' + +Leaf3 configuration: + +.. code-block:: sh + + set interfaces ethernet eth0 address '10.1.3.3/24' + set protocols ospf area 0 network '10.0.0.0/8' + + ! Our first vxlan interface + set interfaces bridge br241 address '172.16.241.1/24' + set interfaces ethernet eth1 vif 241 bridge-group bridge 'br241' + set interfaces vxlan vxlan241 bridge-group bridge 'br241' + set interfaces vxlan vxlan241 group '239.0.0.241' + set interfaces vxlan vxlan241 link 'eth0' + set interfaces vxlan vxlan241 vni '241' + + ! Our seconds vxlan interface + set interfaces bridge br242 address '172.16.242.1/24' + set interfaces ethernet eth1 vif 242 bridge-group bridge 'br242' + set interfaces vxlan vxlan242 bridge-group bridge 'br242' + set interfaces vxlan vxlan242 group '239.0.0.242' + set interfaces vxlan vxlan242 link 'eth0' + set interfaces vxlan vxlan242 vni '242' + +As you can see, Leaf2 and Leaf3 configuration is almost identical. There are +lots of commands above, I'll try to into more detail below, command +descriptions are placed under the command boxes: + +.. code-block:: sh + + set interfaces bridge br241 address '172.16.241.1/24' + +This commands creates a bridge that is used to bind traffic on eth1 vlan 241 +with the vxlan241-interface. The IP-address is not required. It may however be +used as a default gateway for each Leaf which allows devices on the vlan to +reach other subnets. This requires that the subnets are redistributed by OSPF +so that the Spine will learn how to reach it. To do this you need to change the +OSPF network from '10.0.0.0/8' to '0.0.0.0/0' to allow 172.16/12-networks to be +advertised. + +.. code-block:: sh + + set interfaces ethernet eth1 vif 241 bridge-group bridge 'br241' + set interfaces vxlan vxlan241 bridge-group bridge 'br241' + +Binds eth1 vif 241 and vxlan241 to each other by putting them in the same +bridge-group. Internal VyOS requirement. + +.. code-block:: sh + + set interfaces vxlan vxlan241 group '239.0.0.241' + +The multicast-group used by all Leafs for this vlan extension. Has to be the +same on all Leafs that has this interface. + +.. code-block:: sh + + set interfaces vxlan vxlan241 link 'eth0' + +Sets the interface to listen for multicast packets on. Could be a loopback, not +yet tested. + +.. code-block:: sh + + set interfaces vxlan vxlan241 vni '241' + +Sets the unique id for this vxlan-interface. Not sure how it correlates with +multicast-address. + +.. code-block:: sh + + set interfaces vxlan vxlan241 remote-port 12345 + +The destination port used for creating a VXLAN interface in Linux defaults to +its pre-standard value of 8472 to preserve backwards compatibility. A +configuration directive to support a user-specified destination port to override +that behavior is available using the above command. + +Older Examples +^^^^^^^^^^^^^^ + +Example for bridging normal L2 segment and vxlan overlay network, and using a +vxlan interface as routing interface. + +.. code-block:: sh + + interfaces { + bridge br0 { + } + ethernet eth0 { + address dhcp + } + loopback lo { + } + vxlan vxlan0 { + bridge-group { + bridge br0 + } + group 239.0.0.1 + vni 0 + } + vxlan vxlan1 { + address 192.168.0.1/24 + link eth0 + group 239.0.0.1 + vni 1 + } + } + +Here is a working configuration that creates a VXLAN between two routers. Each +router has a VLAN interface (26) facing the client devices and a VLAN interface +(30) that connects it to the other routers. With this configuration, traffic +can flow between both routers' VLAN 26, but can't escape since there is no L3 +gateway. You can add an IP to a bridge-group to create a gateway. + +.. code-block:: sh + + interfaces { + bridge br0 { + } + ethernet eth0 { + duplex auto + smp-affinity auto + speed auto + vif 26 { + bridge-group { + bridge br0 + } + } + vif 30 { + address 10.7.50.6/24 + } + } + loopback lo { + } + vxlan vxlan0 { + bridge-group { + bridge br0 + } + group 239.0.0.241 + vni 241 + } + } + + +.. target-notes:: + +.. _RFC7348: https://datatracker.ietf.org/doc/rfc7348/ |