VXLAN Technical Analysis-(1) VXLAN Brief introduction

VXLAN Technical Analysis-(1) VXLAN Brief introduction

Vxlan Brief Introduction

The vxlan,virtual extensible LAN, as the name implies, is an extended version of VLANs. Vxlan technology is primarily used to enhance the network's ability to expand in cloud computing environments.

The Vxlan uses UDP packets to encapsulate the Ethernet message, which enables cross-IP data transmission with a UDP port number of 4789. The end device of the VXLAN is called the Vtep,vxlan tunnel endpoint, which is generally assumed by the ports of the physical switch (Nexus 5600/9000) or Virtual switch (Open Vswitch/nexus 1000v), Responsible for encapsulation and encapsulation of VXLAN messages.

VLANs provide a logical layer of two-tier boundaries and broadcast domains. Compared to traditional VLANs, Vxlan extends the following features:

1. Provide two-layer connectivity across three levels, in popular parlance is the two-layer tunnel.

2. Using the 24bit Vnid, the two-tier logic domain provided by the original 12bit VLAN ID is greatly expanded.

3. Use ECMP routing instead of STP to better utilize link bandwidth within data center fabric.

Vxlan was first proposed by VMware and Cisco and has been successively supported by other vendors such as Arista, Broadcom, Citrix, Intel and Redhat. It is now standardized as an IETF RFC7348.

Vxlan Message Format

The Vxlan introduces a 8-byte Vxlan header that contains 24bit of Vnid and some reserved bits. Plus the udp/ip/ethernet header, which adds 50 bytes of overhead compared to the original Ethernet frame.

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Vxlan packet encapsulation and unpacking path (unicast as an example)

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VXLAN Technical Analysis-(1) VXLAN Brief introduction