What Is VXLAN and Why Do We Need It?

With cloud initiatives and virtualization technologies continually shaping our understanding and demands for networks, VXLAN, as a key technology, is quietly emerging, altering the constraints of traditional networks, and bringing forth entirely new possibilities for network architecture. This article will provide you with a comprehensive understanding of VXLAN, its role in networking, and the reasons why we need it.

What Is VXLAN, Is It Necessity?

VXLAN is a virtualization network technology created by the Internet Engineering Task Force in 2014. It is an extension of layer two VLAN, designed to provide similar functionality as VLAN but with greater scalability and flexibility. VXLAN allows multiple organizations or users to share a single physical network, with each user unable to see the network traffic of any other organization. Essentially, VXLAN is a tunneling technology that establishes a logical tunnel on an IP network between the original network device and the target network device, encapsulating and forwarding packets from the user side through the tunnel.

So, why is VXLAN technology necessary? This needs to be explained from several aspects:

Scalability:

Due to VLAN's limitation of only having 12-bit identifiers, it can support a maximum of 4096 unique VLANs. This limitation makes it inadequate for large-scale data centers or cloud computing applications. VXLAN, on the other hand, uses 24-bit VXLAN Network Identifiers (VNIs) and can support up to 16777215 unique VXLAN identifiers. This feature provides greater scalability to meet the demands of any scenario.

Adaptation to Large-Scale Virtualization:

With VXLAN offering up to 16777215 unique identifiers, far exceeding VLAN's 4096. VLAN, as the network scales, requires individual configuration and management for each user. VXLAN introduces logical isolation, simplifying management. VXLAN also allows virtual machines and containers to communicate across different subnets, increasing flexibility and enabling more unrestricted migration of virtual machines and containers, not constrained by physical topology.

Overcoming Physical Network Limitations:

VXLAN's packet encapsulation using UDP allows it to operate on any network capable of transmitting UDP packets. As long as UDP packets can be forwarded from the encapsulating VXLAN tunnel endpoint to the de-encapsulating VTEP, the physical layout and distance between underlying network nodes become less important. This is a crucial factor enabling VXLAN to overcome limitations imposed by the physical network.

What is the difference between VLAN and VXLAN?

VXLAN, as an extension of VLAN, exhibits differences between them that are much more significant than they might initially appear. While both belong to the realm of network virtualization, they differ significantly in aspects such as network isolation and flexibility. Let me guide you through their distinctions:

Layer of Operation:

VLAN, implemented at the data link layer (Layer 2), achieves logical network isolation by segregating different ports into distinct virtual networks on a switch. On the other hand, VXLAN, operating at the network layer (Layer 3), establishes logical tunnels on an IP network, encapsulating and transmitting data packets from one VXLAN network endpoint to another, facilitating communication between virtual networks.

Identifier Bit Size:

As mentioned earlier, VLAN is confined to a 12-bit VLAN identifier, supporting at most 4096 unique VLANs. While sufficient for some small-scale applications, VLAN proves inadequate for large-scale deployments. In contrast, VXLAN boasts a 24-bit VXLAN network identifier (VNI), supporting a whopping 16777215 unique VXLAN identifiers, making it well-suited for more extensive and complex network requirements.

Network Isolation and Flexibility:

VLAN provides only basic network isolation, requiring separate configuration and management for each user in large-scale network environments. Additionally, VLAN imposes limitations on cross-subnet communication. VXLAN, however, introduces the concept of logical isolation, simplifying management. Furthermore, VXLAN allows virtual machines and containers to communicate across different subnets, providing greater flexibility and facilitating easier migration.

Operational Mechanism:

VLAN utilizes the 802.1Q standard, adding VLAN tags to the frame header to mark the virtual network to which a data packet belongs. In contrast, VXLAN employs UDP encapsulation, creating a logical tunnel on an IP network between the source and destination network devices. It encapsulates Layer 2 Ethernet frames into UDP and transmits them through Layer 3 networks. VXLAN's advantage lies in its ability to operate on any network supporting UDP packet transmission, with the physical layout and distance between underlying network nodes posing no limitations, as long as UDP packets can be forwarded from the encapsulating VXLAN tunnel endpoint (VTEP) to the de-encapsulating VTEP.

Application of VXLAN

In data center networks, the deployment of a spine-leaf architecture is employed to realize VXLAN-based data centers. The incorporation of MLAG enhances the reliability of the network architecture while ensuring optimal performance. With the presence of VXLAN, this solution ensures flexible deployment of extensive virtual machine migrations and user services. Tailored for large-scale data centers or cloud computing environments, it addresses the demands of larger and more complex network requirements.

Conclusion

In conclusion, VXLAN emerges as a crucial technology for modernizing network architectures, addressing scalability limitations, and enabling flexible deployments in large-scale data centers and cloud computing environments. As a layer 3 network virtualization technology, VXLAN not only ensures user privacy and security but also guarantees the independence of traffic data. For any additional inquiries or clarification, please feel free to contact QSFPTEK's CCIE/HCIE engineers at [email protected].