I have configured in a lab logical switch, distributed router, distributed firewall and everything is work fine.

But then I thing about real live environment I am a little bit confused about VTEPs and VXLAN. I understand that VTEP encapsulate the original frame with outer header with VXLAN IP and MAC to deliver the original frame over L3 transport network. But I don't understand requirements for physical network. Does every switch, for example cisco 2900 or cisco 3750 will understand vxlan encapsulated frames from VTEp adapters? Do I need to do some extra configuration on physical switch except of MTU 1600? Then I google I always see nexus 9000 switch which support VXLAN and has VTEP.

So my question is: can my logical switch distributed over physical environment with catalyst 2900, 3700 and etc series switch and routers like 2900 or ASR/ISR routers? will my "non-data center equipment" understand vxlan encapsulated frames or I need only NEXUS series switch to do this?

Thank you very much )

  • To your non-VXLAN switches, the traffic is just jumbo (>1500) multicast frames. I'll have to see if I can find the uber-diagram of how all this crap interoperates. (it's an eye watering, complex mess.)
    – Ricky
    Dec 2, 2018 at 3:48
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer.
    – Ron Maupin
    Dec 25, 2018 at 10:12

1 Answer 1


Figure 3

Figure 3 (above) in this Cisco Whitepaper shows part of the story, but as they say, "this example assumes that address learning has been done on both sides, and corresponding MAC-to-VTEP mappings exist on both VTEPs." Unfortunately, that mapping is 99% of the Magic(tm) that is VXLAN. (See figure 5)

In the simplest terms, VXLAN is a mechanism for making intelligent layer-2 bridges. It does for ethernet what IPSec does for IP. ('tho not necessarily with any encryption) The VTEP's are the end-points for tunnels connecting various layer-2 domains. In the example above, host-a and host-b may not be in the same datacenter, or even on the same continent.

  • Dear Ricky, thank you for your reply, As I understand from the link the vxlan header is a part of inner header? The outer header is the same standart format for Ip and Ethernet header? So catalyst switch will forward this frame as normal frame, we only need to extend MTU to 1600? Do I understand correctly or not ?
    – orkhan
    Dec 2, 2018 at 9:56
  • Mostly yes. The VTEP mapping process uses multicast, so you need to make sure the switches are ok with it. In more complex configurations, multicast routing is needed so the VTEP's can see each other.
    – Ricky
    Dec 2, 2018 at 22:36

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