Introduction to VXLANBy Mohammed Umair

VXLAN Overview VXLAN provides large number of

broadcast segments as many as 16 million segments

Data-traffic will be forwarded loop free. Data-traffic using VXLAN can be load-

balanced on ECMP.

VXLAN Terminologies (As per RFC-7348) VXLAN - Virtual eXtensible Local Area

Network VM - Virtual Machine VNI – Virtual Network Identifier (or

VXLAN Segment ID) VTEP - VXLAN Tunnel End Point. An

entity that originates and/or terminates VXLAN tunnels

Why VXLAN A Physical Server can have multiple Virtual

machines with its own MAC Current VLAN limit of 4094 is inadequate,

when traffic isolation is required between the group of VM’s across the Data-Center

Further to avoid Loops STP blocks redundant links connected between switches, this is problem since data-center operators pay for each and every port.

Why VXLAN Contd.. Further using STP, one cannot achieve

load-balancing of Data-Traffic. With current Layer2 model, all the

switches in Data-center must have to learn all MAC address for proper forwarding of traffic.

How VXLAN Works VXLAN is a overlay technology, that

works on Layer3 underlay A native/original Data packet will be

encapsulated with VXLAN and IP header in VTEP (VXLAN tunnel end points).

A VTEP is as device that supports VXLAN, they can be end hosts or Network switches/routers.

How VXLAN Works contd… A VTEP will encapsulate a data-packet by adding number of

fields as belowa) Outer media access control (MAC) destination address (MAC address of the tunnel endpoint VTEP, or next Router)b) Outer MAC source address (MAC address of the tunnel source VTEP)c) Outer IP destination address (IP address of the tunnel endpoint VTEP)d) Outer IP source address (IP address of the tunnel source VTEP)e) Outer UDP headerf) A VXLAN header that includes a 24-bit field—called the VXLAN network identifier (VNI)

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