8G FC versus FCoE--distinguishing myth from reality.

Over the last several years, network convergence has evolved as the almighty solution to all problems in the data centre network. Struggling against rising energy bills and operating expenditures, IT managers have been pushed to believe that only a converged Ethernet infrastructure can solve their problems.

By converging LAN, SAN and other data centre networks onto a single underlying infrastructure, enterprises can realise profound cost savings. But in a typical data centre environment, the consolidation of sites, hardware and expertise into a seamless network means bringing together a wide variety of protocols--including FC (Fibre Channel), Ethernet, ESCON (Enterprise Systems Connection) and FICON (Fibre Connection).

Merely converging FC and Ethernet onto a single platform isn't the solution that will satisfy enterprise customers. It's true that those are the two highest-volume interfaces in today's data centres. However, pushing for a new single standard like Converged Enhanced Ethernet (CEE) will not cause the other interfaces and their respective legacy equipment to disappear over night.

It is important to consider the security and stability of a single converged platform. Multiple networks may require more management, but if problems occur, it is much easier to isolate the problem without affecting other networks. However, it is conceivable that if a single converged platform was in operation and problems were to occur, there would be significantly greater risk that more downtime and more issues would arise as staff tried to isolate problems. Despite concerns, the future looks bright for convergence and the Ethernet protocol in the SAN market. However, today's market still shows that 8G FC interfaces continue to grow, even though some analysts never expected 8G FC to become a commercial success. Skyrocketing sales numbers for 8G FC have helped BROCADE to gain significant market share from its rivals. Cisco learned the hard way that just having FCoE and Data Centre Ethernet switches was not enough. Today even Cisco, the biggest proponent of Data Centre Ethernet, is offering 8G FC as an interface on its FC switches.

Service providers are beginning to support 8G FC as the standard for WAN transport over their networks, too. In January 2009, ADVA Optical Networking and COLT, a leading provider of data, voice and managed enterprise services, announced the market's first deployment of an 8G FC service over distance. Featured within a customer's SAN, the new service, built specifically upon the ADVA FSP 3000 system, provided a point-to-point link that stretched beyond 135km.

At that time, ADVA Optical Networking and COLT Telecom were the only companies capable of deploying 8Gbit/s FC over distance. Since then, the landscape has incorporated even more 8G FC. The previously dominant 2G FC and 4G FC interfaces have been replaced with 8G FC connectivity, while support for 8G FC transport has become mandatory for all data centre networking environments.

But what about FCoE and Data Centre Ethernet? They still remain, but now only as interconnect protocols for rack-mounted servers that minimize the amount of required network adapters and cables. The new FCoE switches are now just top-of-the-rack FCoE aggregators that feed signals to the legacy LAN and SAN-switches still in use. Today there is no standard that defines how to implement Inter-Switch-Links between those new Ethernet switches. And even if this standard were to become available, the typical bandwidth would not exceed the bandwidth that can be achieved with 8G FC.

So what's the lesson learned from all this? Don't believe all the marketing slides your network vendor presents to you--reality is a different beast. And ultimately, look out for 16G FC, it could be on your doorstep sooner than you expect!

ADVA Optical Networking is exhibiting at Storage Expo.

Christian Illmer, Senior Director Application and Solution Management Enterprise, ADVA Optical Networking