Simplifying with Network Convergence and FCoE
By Mike McNamara, FCIA Marketing Chair (NetApp) and Ahmad Zamer, FCIA Member (Brocade)

Many enterprise data Centres rely on Ethernet for their LAN and data traffic and on Fibre Channel (FC) networks for their storage infrastructure. With the increased adoption of 10GbE in the data Centre, the availability of Fibre Channel over Ethernet (FCoE), and new lossless 10GbE technologies, it is now possible to consolidate FC storage SAN data flows with LAN and data traffic onto the same shared Ethernet cable. Network I/O convergence will enable enterprises to preserve their existing investments in FC storage, reduce data centre costs and complexity, and simplify network management.

IT Challenges: Maintaining Multiple Networks

Managing two separate networks for IP data and storage adds complexity and costs to the data centre. Enterprises are now looking for new ways to converge their IP and SAN networks to enable the data centre to run more efficiently and cost-effectively while preserving their investments in the FC infrastructure.

Ethernet IP data networks and FC SANs each fill an essential role in the data centre, but they are very different in design and functionality. The two networks have their own security constraints and traffic patterns and utilize separate management toolsets. As a result, each network must be built and maintained on its own dedicated, isolated infrastructure, requiring separate cabling and network interfaces on each server.

The majority of today’s data centres maintain multiple networks for separate purposes. Most use Ethernet for their local area networks (LANs) to transfer small amounts of information across short or long distances or in clustered computing environments. Ethernet provides a lower cost way to support a variety of data types, including corporate LANs, voice-over-IP telephony, and storage with NFS, CIFS, and iSCSI.

Others use Fibre Channel for storage area networks (SANs) to provide access to block I/O for applications like booting over SANs, mail servers, and large data-intensive databases. FC SANs are an excellent solution for storage consolidation, centralized storage management, high performance, reliability, and business continuance. The nature of purpose built networks may result in higher costs than general-purpose network technologies like Ethernet.

Organizational Issues

In traditional data centre environments, the storage group owns and operates the FC SAN and the networking group owns the Ethernet LAN. Since the two groups have been historically separate, introducing FCoE into the data centre may bring with it the possibility of streamlining some IT practices.

Cultural, political, organizational, and behavioral concerns in data centre and provisioning paradigms need to be taken into consideration when introducing FCoE into data. Some new business processes and procedures may need to be adopted to ensure that proper control mechanisms are in place for networks with server I/O consolidation. Purchasing patterns may also change and the reliability of Ethernet networks will have to be increased.

With the convergence of FC and LAN traffic over lossless Ethernet with FCoE, these two traditionally separate network realms overlap. Implementing FCoE requires little if any additional IT training. FCoE leverage the existing IT expertise and skill sets of the enterprise’s IP data and FC teams. Role-based management features in management applications allow the FC group to continue owning and operating the SAN, and the IP networking group to continue owning and operating the data network.

Fibre Channel over Ethernet

Fibre Channel over Ethernet enables organizations to transport LAN and FC SAN storage traffic on a single, shared Ethernet cable. In this way, the converged network can support LAN and SAN data types, reducing adapters and cabling requirements in the data centre while simultaneously lowering the power and cooling loads associated with that equipment. There are also fewer support points when converging to a unified network, which helps reduce the management burden.

FCoE is enabled by an enhanced 10GbE Ethernet technology commonly referred to as Data Center Bridging (DCB) or Converged Enhanced Ethernet (CEE). Tunneling protocols, such as FCiP and iFCP, use IP to transmit FC traffic over long distances; however, FCoE is a layer-2 encapsulation protocol that uses Ethernet physical transport to transmit FC data. Planned enhancements in Ethernet standard, such as the ability to provide lossless fabric characteristics over a 10-Gigabit link, will enable FCoE.

FCoE delivers significant value to organizations that are looking to consolidate server I/O, network, and storage interconnects by converging onto a single network storage technology. For data centres with large investments even the simplest reduction in the amount of equipment to manage can reap benefits. Sharing the same converged network fabricremoves the requirement of dedicated networks, significantly reducing TCO by preserving existing infrastructure investments and maintaining backward compatibility with familiar IT procedures and processes.

When and Where to Deploy

While the benefits of using FCoE are certainly compelling, many customers are still waiting to deploy the technology end to end across the enterprise. Fortunately, FCoE convergence does not require a “rip and replace” upgrade in the data Centre and is not a disruptive process. Moving to FCoE can be conducted in a gradual, phased approach. Early FCoE deployments will take place mostly as part of new server deployments in Windows® and Linux® environments where virtualized tier-3 and some tier-2 applications are deployed.

Considering that FCoE is a relatively new technology, initial FCoE deployment will be best suited for access layer server I/O consolidation. As storage traffic requires the new lossless Ethernet, the 10GbE transport remains in need of Link Layer (L2) multipathing and multi hop capabilities. Such features are currently under development, and should become available later in 2010. These capabilities will enable the deployment of larger FCoE networks, which will expand the reach of FCoE beyond access layer server connectivity and I/O consolidation.

Best practices for determining where to deploy FCoE in the enterprise include:

• Environments that already have a Fibre Channel skill base and FC infrastructure
• “Green-field” deployments, where new infrastructure is being introduced to accommodate data growth

Many enterprises will begin the transition to FCoE in their tier-3 or tier-2 applications; with the experience gained in labs or other less mission-critical environments, knowledge may then be applied to some tier-2 and, in somerare instances, tier-1 applications

Enterprises should start implementing FCoE on the access layer server I/O consolidation side–that step may be combined with native FCoE storage deployment; extending FCoE beyond access layer servers should wait for multipathing and multi hop standards to become practical.

Components needed in the data centre

Below is a list of some of the components needed to implement FCoE in the data centre.

• Converged network adapters (CNAs). These combine the functionality of Ethernet NICs and Fibre Channel host bus adapters (HBAs) in an FCoE environment, enabling users to reduce the number of server adapters they need to buy, cut their port count, and eliminate a healthy number of cables.
• FCoE cables. There are currently two options for FCoE cables: the optical cabling generally found in FC SANs and a new type of Twinax copper cabling. FCoE twin cables require less power and are less expensive, but because their distance is limited to fewer than 10 meters, users will likely use optical cabling to go from the top-of-rack switches to the LAN.
• FCoE switches. Users can't go to FCoE directly from their servers to their storage arrays, so they must buy switches that support FCoE/DCB, which connect servers to corporate LANs, SANs, or FCoE storage systems. For the early adopters, that means top-of-rack switches or end or row blades where possible.
• FCoE/DCB storage systems. These are storage systems that support FCoE and converged traffic natively. There are also storage systems that support Fibre Channel to an FCoE switch and FCoE from the switch to the host servers.

Summary

FCoE brings together two leading technologies: the Fibre Channel protocol and an enhanced 10-Gigabit Ethernet physical transport to provide a compelling option for SAN connectivity and networking. And to simplify administration and protect FC SAN investments, FCoE enables IT team members to use the same tools and techniques they use today for managing both the IP and FC storage networks.

The benefits of converged data and storage networks will drive increased adoption of 10GbE in the data centre. FCoE will fuel a new wave of data centre consolidation as it lowers complexity, increases efficiency, improves utilization, and, ultimately, reduces power, space, and cooling requirements.

Companies that are planning new data centres or are upgrading their storage networks should take a serious look at FCoE today. By taking a phased approach to consolidating their data centres networks around Ethernet, customers can economically build out their Ethernet infrastructure over time while protecting investments in FC infrastructure.

For more information about please visit the FCIA website at www.fibrechannel.org and SNIA Europe website at www.snia-europe.org/ethernet_storage.

Back to front page..