Introduction to Virtual Extensible LAN (VXLAN)

This topic is to discuss the following lesson:

Hi Rene, this is a very good lesson on VXLAN, straight to the point and well written.
I’m particularly passionate to this topic because I worked on a VXLAN EVPN Fabric the last year and love this technology.
If I had done a lesson like this when I started It would have been easier to learn the topic…


Hi Rene,
How can we configure vxlan. Could you please explain.

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Hello Bikram

Take a look at the following lesson in order to further understand how to implement a VXLAN topology.

I hope this has been helpful!


This is the BEST explanation document on VXlan available on internet.

Hello Syed

Thanks so much for your positive feedback, it gives us the drive to continue to do our best!


I’m not sure if I posted this question to the correct topic area. My apology if I didn’t. I tried to access “Cisco CSR1000V VXLAN Unicast Configuration” a few minutes ago, but receive an error message. Below is the following error message from Firefox:

404 – Page not found
The page you trying to reach does not exist or has been moved. Please use the navigation menus, the search box, or try one of these instead:


Hello Timothy

Thanks for taking the time to share this with us. Can you clarify from where you tried to access this content? There is no lesson called “Cisco CSR1000V VXLAN Unicast Configuration.” Can you send us the page from which you tried to connect to the failed link?




Please see URL below.

I received periodic topic discussions via email, but for some reason when I click the link I’m unable to access.


Hi Timothy

Thanks for sharing that, I’ll let @ReneMolenaar know.


I fixed this, somehow a draft post got published :slight_smile: Thanks for letting us know!

Thanks for this lesson.

<Traditional layer 2 networks have issues because of three main reasons:

Limited amount of VLANs.
Large MAC address tables.>

My understanding is as follows. Could you please explain ?

  1. Spine-leaf topology solved the Spanning tree issue. STP is not an issue in VxLAN.
  2. Limited amount of VLANs : This is the essential why vxlan needs.
  3. Large MAC address tables : I’am not sure how vxlan solve this problem. This issue is common in virtualization.

Spine-leaf was not ip network. It becomes ip underlay to bind MAC learning to a multicast group and to deliver VxLAN frame efficiently. Is it true ?


Hello Michael

First of all, we must make a distinction between VXLAN and spine-leaf. The first is a tunnelling protocol while the second is a network topology/architecture. They can work together, but they don’t necessarily have to be implemented together.

Actually, the spine-leaf topology doesn’t solve the inefficiency of STP. If you create an L2 spine-leaf topology, without any additional configuration parameters, STP will severely limit the available bandwidth. The solutions to the STP problem (regardless of the topology underneath) is:

  • to employ VXLAN
  • to break the network into smaller network segments/subnets
  • to introduce what is known as Transparent Interconnection of Lots of Links (TRILL) or shortest path bridging (SPB) to replace STP.

You can choose which solution to use depending on your requirements and what your equipment supports.

This is one of the basic problems that VXLAN solves, allowing extensively large datacenters to have more than the 4096 VLANs that normal Ethernet provides.

Because you are able to segment the datacenter network into tens of thousands of subnets, you can keep the number of hosts per subnet very small. The result is that the MAC address tables created for each subnet remain small.

Again, spine-leaf is a particular architecture, not necessarily associated with VXLAN. If you choose to use it, you can. If not, you don’t have to. But if you do, yes, it becomes the underlay routed network.

I hope this has been helpful!