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Add VXLAN to network interfaces chapter
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Christian Poessinger
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@ -471,6 +471,285 @@ Results in:
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description "Description"
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}
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VXLAN
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-----
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VXLAN is an overlaying Ethernet over IP protocol. It is described in RFC7348_.
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If configuring VXLAN in a VyOS virtual machine, ensure that MAC spoofing
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(Hyper-V) or Forged Transmits (ESX) are permitted, otherwise forwarded frames
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may be blocked by the hypervisor.
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Multicast VXLAN
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^^^^^^^^^^^^^^^^
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Example Topology:
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PC4 - Leaf2 - Spine1 - Leaf3 - PC5
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PC4 has IP 10.0.0.4/24 and PC5 has IP 10.0.0.5/24, so they believe they are in
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the same broadcast domain.
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Let's assume PC4 on Leaf2 wants to ping PC5 on Leaf3. Instead of setting Leaf3
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as our remote end manually, Leaf2 encapsulates the packet into a UDP-packet and
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sends it to its designated multicast-address via Spine1. When Spine1 receives
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this packet it forwards it to all other Leafs who has joined the same
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multicast-group, in this case Leaf3. When Leaf3 receives the packet it forwards
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it, while at the same time learning that PC4 is reachable behind Leaf2, because
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the encapsulated packet had Leaf2's IP-address set as source IP.
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PC5 receives the ping echo, responds with an echo reply that Leaf3 receives and
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this time forwards to Leaf2's unicast address directly because it learned the
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location of PC4 above. When Leaf2 receives the echo reply from PC5 it sees that
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it came from Leaf3 and so remembers that PC5 is reachable via Leaf3.
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Thanks to this discovery, any subsequent traffic between PC4 and PC5 will not
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be using the multicast-address between the Leafs as they both know behind which
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Leaf the PCs are connected. This saves traffic as less multicast packets sent
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reduces the load on the network, which improves scalability when more Leafs are
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added.
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For optimal scalability Multicast shouldn't be used at all, but instead use BGP
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to signal all connected devices between leafs. Unfortunately, VyOS does not yet
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support this.
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Configuration commands
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^^^^^^^^^^^^^^^^^^^^^^
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.. code-block:: sh
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interfaces
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vxlan <vxlan[0-16777215]>
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address # IP address of the VXLAN interface
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bridge-group # Configure a L2 bridge-group
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description # Description
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group <ipv4> # IPv4 Multicast group address (required)
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ip # IPv4 routing options
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ipv6 # IPv6 routing options
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link <dev> # IP interface for underlay of this vxlan overlay (optional)
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mtu # MTU
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policy # Policy routing options
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remote # Remote address of the VXLAN tunnel, used for PTP instead of multicast
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vni <1-16777215> # Virtual Network Identifier (required)
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Configuration Example
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^^^^^^^^^^^^^^^^^^^^^
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The setup is this:
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Leaf2 - Spine1 - Leaf3
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Spine1 is a Cisco IOS router running version 15.4, Leaf2 and Leaf3 is each a
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VyOS router running 1.2.
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This topology was built using GNS3.
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Topology:
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.. code-block:: sh
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Spine1:
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fa0/2 towards Leaf2, IP-address: 10.1.2.1/24
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fa0/3 towards Leaf3, IP-address: 10.1.3.1/24
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Leaf2:
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Eth0 towards Spine1, IP-address: 10.1.2.2/24
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Eth1 towards a vlan-aware switch
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Leaf3:
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Eth0 towards Spine1, IP-address 10.1.3.3/24
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Eth1 towards a vlan-aware switch
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Spine1 Configuration:
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.. code-block:: sh
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conf t
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ip multicast-routing
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!
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interface fastethernet0/2
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ip address 10.1.2.1 255.255.255.0
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ip pim sparse-dense-mode
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!
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interface fastethernet0/3
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ip address 10.1.3.1 255.255.255.0
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ip pim sparse-dense-mode
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!
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router ospf 1
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network 10.0.0.0 0.255.255.255 area 0
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Multicast-routing is required for the leafs to forward traffic between each
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other in a more scalable way. This also requires PIM to be enabled towards the
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Leafs so that the Spine can learn what multicast groups each Leaf expect traffic
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from.
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Leaf2 configuration:
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.. code-block:: sh
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set interfaces ethernet eth0 address '10.1.2.2/24'
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set protocols ospf area 0 network '10.0.0.0/8'
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! Our first vxlan interface
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set interfaces bridge br241 address '172.16.241.1/24'
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set interfaces ethernet eth1 vif 241 bridge-group bridge 'br241'
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set interfaces vxlan vxlan241 bridge-group bridge 'br241'
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set interfaces vxlan vxlan241 group '239.0.0.241'
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set interfaces vxlan vxlan241 link 'eth0'
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set interfaces vxlan vxlan241 vni '241'
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! Our seconds vxlan interface
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set interfaces bridge br242 address '172.16.242.1/24'
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set interfaces ethernet eth1 vif 242 bridge-group bridge 'br242'
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set interfaces vxlan vxlan242 bridge-group bridge 'br242'
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set interfaces vxlan vxlan242 group '239.0.0.242'
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set interfaces vxlan vxlan242 link 'eth0'
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set interfaces vxlan vxlan242 vni '242'
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Leaf3 configuration:
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.. code-block:: sh
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set interfaces ethernet eth0 address '10.1.3.3/24'
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set protocols ospf area 0 network '10.0.0.0/8'
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! Our first vxlan interface
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set interfaces bridge br241 address '172.16.241.1/24'
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set interfaces ethernet eth1 vif 241 bridge-group bridge 'br241'
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set interfaces vxlan vxlan241 bridge-group bridge 'br241'
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set interfaces vxlan vxlan241 group '239.0.0.241'
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set interfaces vxlan vxlan241 link 'eth0'
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set interfaces vxlan vxlan241 vni '241'
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! Our seconds vxlan interface
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set interfaces bridge br242 address '172.16.242.1/24'
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set interfaces ethernet eth1 vif 242 bridge-group bridge 'br242'
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set interfaces vxlan vxlan242 bridge-group bridge 'br242'
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set interfaces vxlan vxlan242 group '239.0.0.242'
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set interfaces vxlan vxlan242 link 'eth0'
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set interfaces vxlan vxlan242 vni '242'
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As you can see, Leaf2 and Leaf3 configuration is almost identical. There are
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lots of commands above, I'll try to into more detail below, command
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descriptions are placed under the command boxes:
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.. code-block:: sh
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set interfaces bridge br241 address '172.16.241.1/24'
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This commands creates a bridge that is used to bind traffic on eth1 vlan 241
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with the vxlan241-interface. The IP-address is not required. It may however be
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used as a default gateway for each Leaf which allows devices on the vlan to
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reach other subnets. This requires that the subnets are redistributed by OSPF
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so that the Spine will learn how to reach it. To do this you need to change the
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OSPF network from '10.0.0.0/8' to '0.0.0.0/0' to allow 172.16/12-networks to be
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advertised.
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.. code-block:: sh
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set interfaces ethernet eth1 vif 241 bridge-group bridge 'br241'
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set interfaces vxlan vxlan241 bridge-group bridge 'br241'
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Binds eth1 vif 241 and vxlan241 to each other by putting them in the same
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bridge-group. Internal VyOS requirement.
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.. code-block:: sh
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set interfaces vxlan vxlan241 group '239.0.0.241'
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The multicast-group used by all Leafs for this vlan extension. Has to be the
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same on all Leafs that has this interface.
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.. code-block:: sh
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set interfaces vxlan vxlan241 link 'eth0'
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Sets the interface to listen for multicast packets on. Could be a loopback, not
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yet tested.
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.. code-block:: sh
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set interfaces vxlan vxlan241 vni '241'
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Sets the unique id for this vxlan-interface. Not sure how it correlates with
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multicast-address.
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.. code-block:: sh
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set interfaces vxlan vxlan241 remote-port 12345
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The destination port used for creating a VXLAN interface in Linux defaults to
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its pre-standard value of 8472 to preserve backwards compatibility. A
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configuration directive to support a user-specified destination port to override
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that behavior is available using the above command.
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Older Examples
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^^^^^^^^^^^^^^
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Example for bridging normal L2 segment and vxlan overlay network, and using a
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vxlan interface as routing interface.
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.. code-block:: sh
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interfaces {
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bridge br0 {
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}
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ethernet eth0 {
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address dhcp
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}
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loopback lo {
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}
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vxlan vxlan0 {
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bridge-group {
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bridge br0
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}
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group 239.0.0.1
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vni 0
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}
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vxlan vxlan1 {
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address 192.168.0.1/24
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link eth0
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group 239.0.0.1
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vni 1
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}
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}
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Here is a working configuration that creates a VXLAN between two routers. Each
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router has a VLAN interface (26) facing the client devices and a VLAN interface
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(30) that connects it to the other routers. With this configuration, traffic
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can flow between both routers' VLAN 26, but can't escape since there is no L3
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gateway. You can add an IP to a bridge-group to create a gateway.
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.. code-block:: sh
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interfaces {
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bridge br0 {
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}
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ethernet eth0 {
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duplex auto
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smp-affinity auto
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speed auto
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vif 26 {
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bridge-group {
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bridge br0
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}
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}
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vif 30 {
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address 10.7.50.6/24
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}
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}
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loopback lo {
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}
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vxlan vxlan0 {
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bridge-group {
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bridge br0
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}
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group 239.0.0.241
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vni 241
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}
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}
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WireGuard VPN Interface
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-----------------------
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@ -572,4 +851,5 @@ your peer should have knowledge if its content.
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.. _RFC4862: https://tools.ietf.org/html/rfc4862
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.. _RFC4291: http://tools.ietf.org/html/rfc4291#section-2.5.1
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.. _RFC7348: https://datatracker.ietf.org/doc/rfc7348/
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.. _WireGuard: https://www.wireguard.com
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