Welcome back to the third installment of the VxLAN series! We’re excited to have you join us for another dive into the world of VxLAN. In the previous articles, we covered the basics of VxLAN, including encapsulation, tunnels, and VNI’s. In this article, we will focus on the spine-leaf topology, also known as a fabric.
Contents
Traditional Network Architecture
Before we delve into spine-leaf topology, let’s take a quick look back at the traditional network architecture. This architecture consists of core, distribution, and access layers. The access layer connects hosts and devices, while the distribution layer manages traffic control within a specific area. The core layer provides high-speed transport between different areas.
Introducing Spine-Leaf Topology
Spine-leaf topology, also known as a Clos or ‘Cloh’ network, consists of only two layers: the spine layer and the leaf layer. The leaf layer is where hosts and devices connect, while the spine layer serves as a transit layer for passing traffic. The spine switches connect to the leaf switches, but no other devices connect to the spine switches.
In spine-leaf topology, each leaf switch has a link to every spine switch. These links are all routed and operate at layer-3. Each link requires an IP address at both ends and typically uses a /30 or /31 subnet. Routing protocols such as OSPF or EIGRP are used to manage routing.
Advantages of Spine-Leaf Topology
Spine-leaf topology offers several advantages, particularly in data centers. It limits the layer-2 failure domain, making it a suitable choice for routed networks. Additionally, when combined with VxLAN, devices can move within the fabric without needing to change IP addresses.
Another advantage of spine-leaf topology is its scalability. Need to add more hosts? Simply add more leaf switches. Require additional bandwidth? Add a couple of spine switches. The design remains consistent, only requiring the addition of more switches, links, and IP addresses.
Internet and WAN Connectivity
To add internet and WAN connectivity, as well as functionality such as firewalls, load balancers, and routers, these features are incorporated into the leaf layer. Leaf switches that have routers and firewalls attached to them are known as Border Leaves. These switches represent the connectivity to and from the fabric and handle the redistribution of routes from the overlay into the core routing protocol.
Breaking Into Smaller Fabrics
If a fabric becomes too large to manage effectively, it can be divided into smaller fabrics. These smaller fabrics can then be connected using a super-spine, which functions similarly to a regular spine layer. However, it’s worth noting that this topology is typically utilized in very large fabrics.
Conclusion
Spine-leaf topology, along with VxLAN, provides a scalable and flexible solution for building modern networks. Its simplified two-layer structure, coupled with the ability to support mobility without changing IP addresses, makes it an ideal choice for data centers. By incorporating internet and WAN connectivity at the leaf layer, the fabric remains adaptable to evolving networking requirements.
We hope you’ve enjoyed this article on spine-leaf topology in VxLAN networks. If you want to learn more about the fascinating world of technology, be sure to stay tuned to Techal for future articles. Feel free to leave us a comment with your thoughts and suggestions.
