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This article mainly explains "what is the concept of VXLAN". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Now let the editor take you to learn "what is the concept of VXLAN"?

VXLAN packet forwarding proc

VXLAN establishes tunnels between VTEP to transmit encapsulated Layer 2 data over the Layer 3 network.

The following example demonstrates how data can be transferred over VXLAN:

In the figure, Host-An and Host-B are located in the VXLAN of VNI 10 and communicate through the VXLAN tunnel established between VTEP-1 and VTEP-2.

The data transfer process is as follows:

When Host-A sends data to Host-B, the MAC and IP of Host-B serve as the destination MAC of the packet and the MAC of IP,Host-A serve as the source MAC and IP of the packet, and then send the data through VTEP-1.

VTEP-1 finds the VTEP-2 for MAC-B from the mapping table it maintains, and then performs VXLAN encapsulation, plus VXLAN headers, UDP headers, and outer IP and MAC headers. The outer IP header at this time, the destination address is IP of VTEP-2, and the source address is IP of VTEP-1. At the same time, because the next hop is Router-1, the destination address in the outer MAC header is MAC with Router-1.

After the packet is sent from the VTEP-1, the router of the external network will route the packet according to the outer IP header and finally reach the router Router-2 connected to the VTEP-2.

Router-2 sends the packet to VTEP-2. VTEP-2 is responsible for unblocking the packet, removing the outer MAC header, outer IP header, UDP header and VXLAN header in turn.

VTEP-2 sends the packet to Host-B based on the destination MAC address.

In the above process, we see that VTEP is the core component of VXLAN, which is responsible for the encapsulation and unencapsulation of data. The tunnel is also built between VTEP, and VTEP is responsible for data transmission.

Linux support for VXLAN

VTEP can be implemented with proprietary hardware or pure software. At present, more mature VTEP software implementations include:

Linux with VXLAN kernel module

Open vSwitch

Let's first see how Linux supports VXLAN.

Implementation method:

Linux vxlan creates a UDP Socket, which listens on port 8472 by default.

After receiving the vxlan packet on the UDP socket, Linux vxlan unpacks it and transfers it to a vxlan interface according to the vxlan ID in it, and then transfers it to the virtual machine through the linux bridge to which it is connected.

After receiving the packet from the virtual machine, Linux vxlan encapsulates it as a multicast UDP packet and sends it out from the network card.

At this point, I believe you have a deeper understanding of "what is the concept of VXLAN". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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