Tip

This is the documentation for the 19.02 version. Looking for the documentation of the latest version? Have a look here.

VXLAN Interfaces

Virtual Extensible LAN, or VXLAN, interfaces can be used to encapsulate Layer 2 frames inside UDP, carrying traffic for multiple L2 networks across Layer 3 connections such as between routed areas of a datacenter, leased lines, or VPNs.

VXLAN tunnels are commonly used to bypass limitations of traditional VLANs on multi-tenant networks and other areas that require large scale L2 connectivity without direct connections.

There are two main components to a VXLAN tunnel: The VXLAN tunnel itself, and the bridge domain used to terminate the tunneled traffic to another local interface.

VXLAN Settings

A new VXLAN tunnel is created with the vxlan <tunnel-name> command in config mode, which then enters config-vxlan mode.

Given the instance identifier configured on the VXLAN tunnel, a new interface will be available in TNSR named vxlan_tunnel<id>. For example, with instance 0 the interface is named vxlan_tunnel0.

In config-vxlan mode, the following commands are available:

destination <ip-addr>

Destination IP address for the far side of the tunnel. This can be a multicast address, but if it is, then the multicast interface must also be defined.

encapsulation route-table <rt-table-name>

Routing table used for VXLAN encapsulation.

instance <id>

An instance identifier, typically numbered starting at 0.

multicast interface <if-name>

Interface used for multicast. Required if the destination address is a multicast address.

source <ip-addr>

Source IP address on TNSR used to send VXLAN tunnel traffic.

vni <u24>

VXLAN Network Identifier

Note

The source IP address, destination IP address and encapsulation route table must all be of the same address family, either IPv4 or IPv6.

VXLAN-Related Settings

In addition to the VXLAN settings, there are related settings in bridges and interfaces which are used with VXLAN tunnels.

In config-bridge mode, the arp term command to enable ARP termination is needed for bridges used with VXLAN tunnels.

In config-interface mode, when adding an interface to a bridge, the shg (Split Horizon Group) parameter is required for VXLAN tunnels. This number must be non-zero and the same number must be used on each VXLAN tunnel added to a bridge domain. This prevents packets from looping back across VXLAN interfaces which are meshed between peers.

VXLAN Example

First, create the bridge with the desired set of options:

tnsr(config)# interface bridge domain 10
tnsr(config-bridge)# arp term
tnsr(config-bridge)# flood
tnsr(config-bridge)# uu-flood
tnsr(config-bridge)# forward
tnsr(config-bridge)# learn
tnsr(config-bridge)# exit

Add host interface to bridge domain:

tnsr(config)# int GigabitEthernet3/0/0
tnsr(config-interface)# bridge domain 10 shg 1
tnsr(config-interface)# exit

Create the VXLAN tunnel:

tnsr(config)# vxlan xmpl
tnsr(config-vxlan)# instance 0
tnsr(config-vxlan)# vni 10
tnsr(config-vxlan)# source 203.0.110.2
tnsr(config-vxlan)# destination 203.0.110.25
tnsr(config-vxlan)# exit

Add the VXLAN tunnel to bridge domain:

tnsr(config)# int vxlan_tunnel0
tnsr(config-interface)# bridge domain 10 shg 1
tnsr(config-interface)# exit

VXLAN Status

To view the status of VXLAN tunnels, use the show vxlan command:

tnsr# show vxlan
Name Instance Source IP   Dest IP      Encap Rt   Decap Node IF Name       Mcast IF VNI
---- -------- ----------- ------------ ---------- ---------- ------------- -------- ---
xmpl 0        203.0.110.2 203.0.110.25 ipv4-VRF:0 1          vxlan_tunnel0          10