From the SAN to the WAN

Arthur Cole

The ever increasing need for more storage is driving the popularity of online storage services even as questions over their security and reliability linger. For larger enterprises unwilling to entrust their data to a third party, the ability to extend SAN functionality over the wide area has gained a strong following over the past few years.


Now, it seems that SAN extension technology is heading downmarket as new technologies and networking protocols allow for optimized performance even on a limited budget. The news is particularly good for Fibre Channel users; new IP-based protocols promise to expand their SANs over metropolitan networks.


Just last month, Brocade introduced the 7500E SAN router, an extension for the 7500 device that uses the Fibre Channel over IP (FCIP) protocol to provide entry-level remote data replication. The system is designed for fast deployment for low-end users, and as such has a limited port density and bandwidth capacity -- initially two 4G FC ports and two 50 Mb Ethernet ports -- although it does come with redundant power, compression technology and fabric isolation.


FCIP and a related standard called Internet Fibre Channel Protocol (iFPC) are the two main avenues to extending FC SANS over IP networks. The main difference is that FCIP tunnels data traffic aboard an FC fabric within the IP network, while iFCP handles all routing and fabric services on IP itself, much like iSCSI. A good overview of the two protocols can be found here.


These advances are coinciding with additional developments in optical networking, which can be used for either local enterprise networks or over metro networks. Finisar recently demoed a new laser at the Optical Fiber Communications Conference in San Diego capable of supporting 16 G Fibre Channel networks. The Vertical Cavity Surface-Emitting Laser (VCSEL) is earmarked for optical transceivers for multimode fibre applications. Another recent development is the WRT-780 dual transponder from JDSU, which is capable of either Ethernet or Fibre Channel connectivity between 125 Mbps and 4.25 Gbps.


Extending storage networks over the wide area is the easiest way to ensure that all users have access to an organization's institutional data, not to mention the obvious benefits to data backup and disaster recovery. Access and security issues still remain, but they can be better maintained on a network that's still your own.

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