Interconnecting Fibre Channel SANs Over Optical And IP Infrastructures - Technology Information

Computer Technology Review, May, 2001 by Rick Walsworth

Interconnecting Storage Area Networks (SANs) over Optical and Internet Protocol (IP) infrastructures enables cost-effective, high-performance remote storage services. As storage-consolidation, disaster-recovery, and business-continuance applications take advantage of SAN infrastructures, Fibre Channel SAN deployment accelerates and interconnection demand grows. As a result, the requirement for ubiquitous, cost-effective, high-performance network interfaces becomes paramount for delivering mission-critical services. This creates new opportunities and delivers increased benefits to enterprise, service-provider, and carrier markets.

Though transporting Fibre Channel traffic across dedicated fiber networks is possible, remote access to terabyte-storage resources has been cost prohibitive. Network Attached Storage (NAS) provides a solution for transporting file system data over long distances; however, NAS has significant performance limitations when transporting large blocks of storage data. Since NAS is a file-based storage-networking service, it lacks the scalability to meet the performance requirements of today's high-bandwidth remote-storage applications. Requirements for wire-speed throughput, improved cost efficiencies, and aggregation of data and storage services drive the need for better solutions to remote storage applications

Gigabit Ethernet can extend the SAN infrastructure across Metropolitan-Area Networks (MANs) and Wide-Area Networks (WANs). It also addresses performance issues by providing higher bandwidth at greater efficiencies and lower costs. Most telecommunications carriers offer Gigabit speeds through SONET/SDH infrastructures, with OC-48 (2.5Gbps) at most central offices and OC-192 (10Gbps) throughout the core of their fiber-based telecommunications infrastructures. This provides opportunities to transport Gigabit Ethernet links over carrier infrastructures that are more cost effective than dedicated fiber networks, but still too costly for most small-to-medium enterprises.

Next-generation carrier networks offer leased fiber and managed IP services that operate at gigabit speeds--often at lower cost points--and provide optical packet-switched infrastructures, with the inherent reliability of mesh-network architecture. These alternatives empower users to leverage the existing infrastructure for remote access to centralized storage resources, with instant improvements in performance and significant cost reductions over dedicated fiber links.

The evolution from Gigabit Ethernet to 10 Gigabit Ethernet addresses the need of connecting storage to dark-fiber networks and SONET-optical infrastructures. The adoption rate of this technology promises to be an evolutionary rather than a revolutionary process, offering several key advantages with each advance in technology. The initial market opportunity for each of these phases is significant, with SAN-extension services representing well over a multi-billion market opportunity.

SANs are high-speed networks that enable direct connection between heterogeneous storage devices and servers. The high-speed direct connectivity that SANs provide offers:

* Greater flexibility

* Improved data management

* Increased system throughput

* Simplified and reduced costs of storage administration

Conventional enterprise networks can neither protect nor prioritize high-bandwidth storage traffic from existing data traffic. Moreover, storage traffic would choke most Local Area Networks (LANs).

One of the major benefits of a SAN is its ability to provide an independent storage network within the data center, thereby sidestepping traffic and congestion on a company's LAN. IP-SANs extend the benefits of the SAN beyond the data center, enabling the use of cost-effective remote storage applications for Enterprise and Storage Service Provider deployments.

SAN Benefits

The SAN architecture was created to address issues associated with scalability, reliability, and performance within a data center. By externalizing the storage traffic from the LAN, the SAN removes many bottlenecks associated with directly attached storage architectures. Key differentiators between SAN and other storage network architectures are:

* Fast data access

* Scalability

* Higher availability and reliability

* Improved storage resource sharing

* Extensive management capabilities

A SAN solution is ideal for handling a corporation's multiterabyte storage-networking requirements. Fibre Channel SANs have proven scalability to meet the high-end requirements of an Enterprise Data Center. Moreover, initial SAN installations typically range from 100 to 500GB, although a SAN can be a good business decision for companies with as few as two Microsoft Windows NT servers.

SAN application server hardware can be upgraded without taking the shared storage resource out of service. Moreover, storage resources can be upgraded without halting the application.

In addition, Fibre Channel devices--the core technology behind SAN architecture--are often dual-port solutions. Dual-port capability offers multiple redundant data connections, which provide excellent disaster protection for the network.