Ethernet switches are the plumbing of data center environments. The increased adoption of virtualization and the addition of new applications to Ethernet environments are requiring a re-architecture of data center switching environment. Scalability, simplification and flexibility are the main criteria for these new environments. The solutions that move beyond a single or small group of switches to this new architecture are known as fabrics. While there are standards in process for some of the functionality that enable new fabric architectures (most notably the Layer 2 multipathing technologies of TRILL from IETF and SPB from IEEE), current fabrics are single vendor offerings. All of the offerings described here are Ethernet based, so they can connect to legacy Ethernet environments that are outside of the fabric boundaries. This article will look at the three current fabric solutions that are shipping today; see What is the entry point for networking fabric technology for a discussion of non-fabric alternatives.
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Brocade VCS
Brocade claims the first shipping fabric solutions in the market, VCS technology which ships on VDX switches. The VCS fabric architecture is built with small building blocks; VDX switches are 1U and 2U in height and have flexible “port on demand (PoD)” up to 24 or 60 ports on the latest VDX6730 models. Brocade says that a high percentage of customers that buy VDX switches are using the VCS functionality. The solution can grow to 24 switches managed as a “single chassis”; this does not equate to 1440 usable ports due to connectivity between switches. VCS includes auto-provisioning, greatly decreasing the time to deployment and simplifies management. To use the analogy of a Lego set, Brocade VCS fabrics are small kits that are easy to put together. It is expected that Brocade will expand the offering; in the meantime, hundreds of customers are deploying real fabric solutions using the technology.
VCS technology is TRILL-based, while Brocade has stated that it will support the standard in the future, the upgrade path is not currently known.
Cisco FabricPath
Cisco’s fabric architecture, which is also based on TRILL, is known as FabricPath. Cisco recently did a significant update to its fabric offering. On the Nexus 7000, the second-generation line card supports 48 line-rate 10Gb Ethernet ports and the fabric modules can drive 550Gb/slot. FabricPath is added to the Nexus 5500 family of switches. In the Lego analogy, Cisco has the most diverse set of building blocks, including special pieces to meet specific application requirements. Starting with the Nexus 7000 family, the new Nexus 7009 supports 336 ports of 10Gb Ethernet in 14RU and the largest Nexus 7018 can support up to 768 10Gb ports in 25RU chassis. With the latest updates, Cisco’s fabric can scale to over 12,000 ports in a single fabric. Customers will need to work with their Cisco solution providers to understand the proper architecture to build these environments and the subsequent performance and latency that will result from building the fabric.
The Nexus 7000 family is often the backbone of customer 10Gb Ethernet environments. FabricPath has been deployed in over 500 customer locations; while this may be the most deployed fabric technology, it is a small percentage of Cisco’s Nexus install base (Cisco has NX-OS products – which includes Nexus and MDS products - in over 19,000 customer locations). Cisco continues to expand its portfolio, the recent announcement added to the Nexus 2000 (edge connectivity that are the equivalent of a stand-alone chassis blade, including one in HP blade servers) and Nexus 3000 (low latency switches including increased buffering for Big Data applications) families. The broad portfolio of Nexus products helps users meet the varied technology requirements without splintering operations by having a single OS. Cisco has a strong channel that can help sort out what can be a daunting task of choosing and architecting a proper solution.
Juniper QFabric
Juniper announced its QFabric architecture earlier this year and recently started shipping. The simplicity of the high-level architecture, a switch fabric is managed as a single switch, has a lot of people trying to reconcile the configuration with traditional architectures. In essence, QFabric’s interconnect chassis is equivalent to a large switch chassis and the QFX3500 switches are the blades. Using the Lego analogy, Juniper has a large green foundation on which it can build structures.
Unlike VCS and FabricPath, QFabric is not based on TRILL. Customers are making a commitment to the architecture (starting at around $450,000 for system with a pair of directors and interconnects), but this is similar to buying a large chassis-based environment. Juniper’s architecture is elegant in its design, the edge switches have 40Gb ports to attach to interconnect chassis, and performance and latency stays constant up to the full 6,000-port scale. While Cisco can build a larger single fabric, Juniper could connect a pair of QFabric environments, it would just look like two switches rather than one.
Conclusion
Since growth and change define the reality of data centers, CIOs need to consider new architectures that can deliver high utility and streamline operations. Fabric architectures require significant changes from traditional environments to meet these high demands. Customers that adopt these new architectures can derive a competitive advantage through increased agility and streamlined operations.
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Footnotes: Also see Architecting a Network for Hadoop
Stu Miniman is a Principal Research Contributor for Wikibon. He focuses on networking, virtualization, Infrastructure 2.0 and cloud technologies. Stu can be reached via email (stu@wikibon.org) or twitter (@stu).
Photos by Stuart Miniman, Lego construction with help from his son.
