Hi Manish Gogna,

I already read that website. He posted this article since 2011.
As I used the read other article, if every tenants use CSR1K instead of vShield Edge, they can configure it as VxLAN, they still move VM to other side, but the traffic still forward the primary site. 
What I want to know the limitation of VxLAN if compare the OTV ?

As I understanding, VxLAN is working based on VLAN. Actually, VLAN comes with 12 bits = 4096. I do know that VxLAN just a temporary use if budget concern, that is not a good solution of DCI. 

Do you have any ideas ?

Best Regards,
Chhayheng

Hi Chhayheng,

VXLAN is an overlay (encapsulation) technology that will allow you to extend your Layer 2 across a Layer 3 routed infrastructure.  NSX and ACI both use VXLAN in that way.  it also has the added benefit of supporting a 24 bit VXLAN network identifier (VNID) so where a VLAN can support 4K "ids" VXLAN can support about 6 million VXLAN segments.

I see VXLAN in use in Data Centers as a Data Center (DC) Fabric (think of this as "do it yourself ACI").

I see OTV most commonly when there is an existing vlan based data center that needs to be safely extended over a routed infrastructure or where two data centers need to be tied together at L2.

• Existing Vlan DC to new ACI DC (or other new  DC/SDN technology) for migration
• New SDN DC1 to New SDN DC2 VLAN Extension
• Traditional DC1 to Traditional DC2

OTV can be temporary while the migration takes place or a permanent part of the design.

While strictly speaking VXLAN can be used to extend a DC across multiple sites, I've not seen it used that way and there seems to be some dialog around its suitability as a true "DCI" solution.  

I just ran across this link and it says what I'm trying to say a bit more clearly.

https://cloudarchitectmusings.com/2013/01/03/word-of-caution-about-overextending-the-use-of-vxlan/

I hope this is useful.   If you can provide details around what you are trying to do the community may be able to better guide you.

Claudia