VXLAN and OTV - What is the difference ?

Thanks for the previous responses on the various topics i posted in this blogs. I knew there are lot of topics on the Data-center discussion and people are moving more to the datacenter technologies. It has been seen that there are lot of changes done in the design of the datacenter environment.

Many Vendor started with the concept of  OTV in datacenter environment where they extend the layer-2 traffic across the datacenter or you can say it is the interlinking between two datacenter.
I am sure you all knew about the concept of OTV in detail. If no, let me explain you again.

"OTV(Overlay Transport Virtualization) is a technology that provide layer2 extension capabilities between different data centers. In its most simplest form OTV is a new DCI (Data Center Interconnect) technology that routes MAC-based information by encapsulating traffic in normal IP packets for transit"

Fig 1.1- OTV Traffic Flow

I will not discussed in detail regarding the OTV. The 3 kinds of interfaces and the roles and responsibilities of these interfaces. I am also not going to talk about the design and the recommendations of the OTV in the DCI environment. Please let me know if you required the detail post on this, i will write another article on this.

Let's talk about the other part of the story, VXLAN ( Virtual extensible LAN )  There are lot of questions on VXLAN, If there is OTV then why VXLAN ?

VXLAN (Virtual extensible LAN ) an open IETF specification designed to standardise an overlay encapsulation protocol, capable of relaying layer-2 traffic over IP networks. 

I never touch upon the VXLAN anywhere, i explain a little bit on it, I mean the architecture of the VXLAN.VXLAN identifies individual layer-2 domains using a 24-bit virtual network identifier (VNI), allowing for up to 16 million independent domains to be specified. 

layer-2 Ethernet frames are encapsulated in IP UDP datagrams and are relayed transparently over the IP network. It is the inherent ability to relay unmodified layer-2 traffic transparently over any IP network that makes VXLAN an ideal technology for data center interconnection.

Fig 1.2- VXLAN

Within the VXLAN architecture, virtual tunnel end points (VTEP) perform the encapsulation and de-encapsulation of layer-2 traffic. Each VTEP is identified by an IP address, which is assigned to a virtual tunnel interface (VTI). The VTEP receives standard layer-2 Ethernet frames, selects the correct VNI and forms an IP UDP packet for transmission to one or more destination VTEPs. 

The source IP address is that of the sending VTI; the destination IP address is that of the receiving VTI.The VNI is typically determined based on the IEEE 802.1Q VLAN tag of the frame received. The destination VTEP (or VTEPs in the case of multicast or broadcast traffic) is selected using a destination-to-VTEP map. This map is very similar to the MAC bridging table, except MAC addresses are associated with IP addresses rather than switch interfaces. 

Many People says, Why VXLAN ?
Well VXLAN is extending the VLANs or layer 2 traffic within the datacenter while OTV is the extension of the layer 2 Traffic across the datacenter. VXLAN comes into mind when there is east-west traffic fundamentals comes into picture. It says that every source to the destination with in a network will one hop count far with the help of VXLAN, it means there is a tunnel between the source and destination ( VXLAN-Tunnel ) on the fabric network. 

Fig 1.3- TRILL, VXLAN, OTV and LISP Difference

Cisco is using the concept of VXLAN in ACI infrastructure for the datacenter environment and also used in the SDA infrastructure in Campus or Enterprise networks. Although the concept is same taking the Layer 2 traffic over IP networks.

Fig 1.4 - InterDC and IntraDC extension
This is the main concept of VXLAN and OTV if you are looking for the difference between the same.  It is only the way of deployment of these protocols in the network while some of the enhancements done in one or the other protocol so that it can work accordingly to the demand and the solution of the customer requirement.

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