Stackable switches, long familiar to Ethernet users, were introduced for Fibre Channel by QLogic in 2003. Stacking reduces complexity and cuts costs by providing a stable, highly-expandable transport for aggregate ISL traffic – eliminating the disruption, port waste and management hassles associated with using device ports as ISLs.

In a stackable architecture, each switch features dedicated ports for inter-switch links (ISLs) – that is, for connecting to other switches. These ports run at a much higher bandwidth than the regular data/device ports, and therefore require far fewer connections to achieve specific bandwidth goals.

Need more server or storage ports? Simply add another switch to the stack – no need to move existing cables or to disrupt devices. It’s like having the performance and hands-off convenience of an expensive chassis switch, without the cost overhead of a chassis!

• Low initial cost – Out of the box, dual-speed QLogic 5000 products provide superior performance at a price-per-port competitive with single-speed, non-stacking edge switches.
  
  
• Reduced expansion costs – Multi-switch QLogic networks require up to 50% fewer switches to achieve the same device port counts. And since each stacking port matches the throughput of three device ports, QLogic ISL connections are far less expensive per unit of bandwidth. For instance, a single 20Gb connection (25.5 Gbps actual bandwidth) saves six 8Gb device ports for devices – and eliminates the need for six expensive 8Gb SFPs. Stacking has never made more sense from a budget versus performance perspective!
  
  
• Longer product and topology lifespan – Other vendors force customers to take a non-linear “rip and replace” approach to SAN growth, offering a limited solution at the low end, followed by a radically different (and much more expensive) architecture as the installation matures. QLogic’s modular ISL backbone helps customers pace investments and deployment activities predictably over time, with fewer wrong turns and reversals – even when corporate strategies and directions change.

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