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The intelligent switch, which is currently creating a lot of buzz in the field of storage networking, dates back to the 1980s in the field of telephony. It made its first appearance in voice networks as a means of automating certain aspects of network management, such as provisioning and call handling, to lower administrative costs.
Similarly, when data networks became ubiquitous in the mid-1990s, the intelligent switch once again appeared. In this incarnation, the main purpose of the intelligent switch was to reduce the complexity of network management by automating certain functions. But, the intelligence in the switches was, initially, rudimentary at best. However, over time, the intelligent switch evolved into the super smart routing switches that are available today from vendors such as Extreme Networks, Foundry Networks, and Riverstone Networks.
As storage networks become more complex, the concept of the intelligent switch is again being pressed into service. And, as was the case with local area networks (LANs), vendors are touting automation of management functions as the answer to the problem of the escalating costs of storage area network (SAN) management.
In its reincarnation, the intelligent switch is taking the form of a sophisticated routing switch, which closely parallels many of the LAN routing switches. A recent study authored by Tom Curlin, a principal analyst with the Royal Bank of Canada Capital Markets defines these new routing switches as "devices that combine multiprotocol switching architecture with port-level I/O routing intelligence."
Vendors are introducing intelligent switches to permit heterogeneous SANs - SANs comprised of storage arrays from different vendors - to be managed easily and affordably. While vendors are initially providing embedded virtualization, multiprotocol capability and port-level I/O intelligence, the ultimate goal is to automate SAN storage management through rules-based policies.
Blazing the trail
Thus far, only one SAN routing switch has appeared in the marketplace - the PSX-1000, which was introduced in March 2002 by Pirus Networks of Acton, MA. The PSX-1000 comprises a six-slot carrier-class chassis with redundant power supplies, fans and optional modules. It consists of a networking component, a system component and a storage component layer.
The networking component layer module, which Pirus calls a LAN Resource Card, houses four network processors, providing TCP acceleration, Ethernet switching and security in the LAN environment. In addition, this layer contains eight Gigabit Ethernet ports, which allow the Pirus switch to attach to eight IP-based LANs or SANs.
The system component layer consists of two modules: the 40GB crossbar switch and a Management Interface Card. The crossbar switch, along with associated software, provides the multiprotocol capability in the PSX-1000. The Management Interface Card contains a dedicated microprocessor for system management, and an out-of-band management port.
The storage component layer contains a Storage Resource Card and a Storage I/O Card. The Storage Resource Card consists of four processors that provide file services, iSCSI protocol support and security functions in the SAN domain and 1GB of RAM for data caching. The Storage I/O Card contains four Fibre Channel ports and four gigabit interface converters (GBICs) that support those ports.
All of the hardware functionality is controlled by the PirusView software suite of management software that mainly resides in the Management Information Card (some is distributed to other modules in the system). Specifically, the PirusView software suite supports virtualized block and file services, logical file servers, file system point-in-time copy and browser-based management.
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