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SONET well-suited to carry storage traffic

Posted: 16 Jan 2004 ?? ?Print Version ?Bookmark and Share

Keywords:sonet? fibre channel? data traffic? d-wdm? ip?

The inexorable growth of data and its associated management continue to challenge today's IT managers. Data has become a valuable business commodity and, as such, must be catalogued and secured, available for use at a moment's notice.

Heightened awareness of the economic costs associated with any loss of real-time access to data and its attendant interruption of business continuity - along with a recognition of the privacy issues associated with data, such as patient records, e-mails and electronic transaction records - has led to a tightening of the regulatory requirements governing the storage of information.

Underscoring the new face of regulation as it pertains to stored data are two recent events: the implementation of the Health Insurance Portability and Accountability Act, which governs access to patient records, and the levying of an $8.35 million fine by the Securities and Exchange Commission, in tandem with Massachusetts securities regulators and the National Association of Securities Dealers, against six firms for failure to retain e-mail records.

With prescriptive regulation, data growth, privacy and business self-interest driving the ongoing demand for storage, there has been a corresponding growth in the demand on network storage assets. Further, in the post-9/11 environment, businesses are taking a closer look at technologies that support the networking of SANs over distance, particularly to support business continuity and disaster recovery initiatives.

According to a research report recently published by Infonetics, the proportion of businesses interconnecting their geographically separated SANs is expected to increase from 18 percent today to 33 percent by 2005. Such a forecast provides additional evidence of the need for a cost-effective solution for the networking of SANs over distance.

Going the distance

Most existing SANs are based on Fibre Channel, a data management protocol that encapsulates the command systems used to control disk arrays. Included in the protocols supported by Fibre Channel are SCSI, which is used to connect RAID storage, as well as Enterprise Systems Connection and Fibre Connection - IBM-developed protocols that are used for mainframe-attached storage.

Before the need arose to extend storage traffic over distance, legacy storage protocols like Fibre Channel were the unquestioned standards for connecting devices within a SAN. As business continuity and disaster recovery concerns have fueled the need to extend SAN connectivity, two methods for extending the distance between storage devices have been implemented.

One is to transport the native Fibre Channel traffic using a mechanism that does not interfere with the Fibre Channel stream. SONET and DWDM transport satisfy that approach. The other method is to employ some form of adaptation that modifies the information being transported to facilitate its transport using an established protocol such as IP.

The trade-off between the two approaches centers on efficiency and cost. Adaptation reduces transport efficiency and potentially can affect the performance of the underlying application. The ideal option would be to support the transport of the native Fibre Channel traffic, since that would offer the greatest probability for preserving application performance.

Up to now, most SAN extension applications across metro-wide distances have used DWDM, which supports native Fibre Channel extension. But DWDM typically requires dedicated fiber, which can be expensive, and it is limited to MAN distances. IP-based extension methods such as Fibre Channel-over-IP support transport over WAN distances but require adaptation. SONET-based connectivity takes both the cost and adaptation impediments off the table and allows native Fibre Channel extension over WAN distances.

SONET connectivity is among the most widely available, affordable and well-understood networking technologies in existence. With more than 230,000 network elements deployed in North America alone, SONET stands as the logical choice for all kinds of networking applications. The key to leveraging SONET successfully is to optimize the transport of different types of traffic over the network. The networking of storage islands using SONET infrastructure presents an opportunity to exploit a proven, widely distributed asset.

- Richard Orgias

Director, Optical Networks Marketing

Nortel Networks Ltd

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