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Virtual Chassis Fabric Overview
The Juniper Networks Virtual Chassis Fabric (VCF) provides a low-latency, high-performance fabric architecture that can be managed as a single device. VCF is an evolution of the Virtual Chassis feature, which enables you to interconnect multiple devices into a single logical device, inside of a fabric architecture. The VCF architecture is optimized to support small and medium-sized data centers that contain a mix of 1-Gbps, 10-Gbps, and 40-Gbps Ethernet interfaces.
Video 1: What is Virtual Chassis Fabric?
A VCF is constructed using a spine-and-leaf architecture. In the spine-and-leaf architecture, each spine device is interconnected to each leaf device. A VCF supports up to twenty total devices, and up to four devices can be configured as spine devices. See Figure 1 for an illustration of the VCF spine-and-leaf architecture.
Figure 1: VCF Spine-and-Leaf Architecture
Each spine device must be a QFX5100 device. In an optimal VCF configuration, the leaf devices are also QFX5100 devices. You can, however, also configure QFX3600, QFX3500, and EX4300 switches as leaf devices. See Understanding Virtual Chassis Fabric Components for more information about the spine-and-leaf architecture.
A VCF provides the following benefits:
- Latency—VCF provides predictable low latency because it uses a fabric architecture that ensures each device is one or two hops away from every other device in the fabric. The algorithm that makes traffic-forwarding decisions in a VCF contains the built-in intelligence to forward traffic by using the optimum available path to the destination, further ensuring predictable low latency for traffic traversing the VCF.
- Resiliency—The VCF architecture provides a resilient framework because traffic has multiple paths across the fabric. Traffic is, therefore, easily diverted within the fabric when a device or link fails.
- Flexibility—You can easily expand the size of your VCF by adding devices to the fabric as your networking needs grow.
- Investment protection—In environments that need to expand because the capabilities of a traditional QFX5100, QFX3600, QFX3500, or EX4300 Virtual Chassis are maximized, a VCF is often a logical upgrade option because it enables the system to evolve without having to remove the existing, previously purchased devices from the network.
- Manageability—VCF provides multiple features that simplify configuration and management. VCF, for instance, has an autoprovisioning feature that enables you to plug and play devices into the fabric after minimal initial configuration. VCF leverages many of the existing configuration procedures from a Virtual Chassis, so that you can configure and maintain a VCF easily if you are already familiar with the procedures for configuring and maintaining a Virtual Chassis.
