HP StorageWorks 2/24 FW 07.00.00/HAFM SW 08.06.00 McDATA Products in a SAN Env - Page 116
Fabric Initialization, Installing high-port count directors such as the Intrepid 10000
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Planning Considerations for Fibre Channel Topologies 3 Fabric Initialization When multiple directors or switches are connected, E_Port (ISL) communication must be established between fabric elements and the fabric must be initialized. During fabric initialization, the fabric elements: • Establish the operating mode for connected E_Port pairs and exchange link parameters (E_Port names, timeout values, classspecific information, and flow control parameters). • Exchange fabric parameters, select a principal switch, and assign Domain_IDs to all switches. • Employ a routing protocol to establish the shortest path through the fabric and program route tables for each fabric element. • Exchange the active zone set to ensure uniform zoning is enforced between all fabric elements. Fabric initialization is not a serial process. The process executes concurrently across all ISLs in the fabric, causing a massive flood of Class F traffic that must processed to the embedded port of each fabric element within a specified (fabric-wide) E_D_TOV. If the fabric consists of a large number of elements (and therefore ISLs), Class F traffic may not be processed within the E_D_TOV, resulting in error recovery operations, timeouts, segmented links, or fabric failure. Because of these problems, a fabric with a high ISL count is more difficult to build. Problems associated with a large fabric are not directly related to the large number of fabric elements but to the large number of ISLs associated with the elements. Installing high-port count directors (such as the Intrepid 10000 Director) as SAN building blocks provides a larger number of non-blocking Fibre Channel ports. Large fabrics built around these directors require fewer additional fabric elements (smaller directors and fabric switches) and ISLs. The Intrepid 10000 Director also supports high-bandwidth (10.2000 Gbps) ISLs that reduce the fabric's total ISL count. In addition, fabrics and sub-fabrics can be merged or maintained as separate entities through flexible partitioning provided by the Intrepid 10000 Director. Large fabrics benefit from deterministic non-blocking performance, less ISL congestion, and better cable management - performance that is not possible from a fabric constructed with smaller port-count switches interconnected with multiple ISLs. 3-30 McDATA Products in a SAN Environment - Planning Manual