HP StorageWorks 2/24 FW 07.00.00/HAFM SW 08.06.00 McDATA Products in a SAN Env - Page 96

Planning Considerations for Fibre Channel Topologies 3 FL_Port Connectivity Sphereon 4300 and 4500 Fabric Switches provide loop connectivity through GX ports that are active as FL_Ports. The ports provide port addressing, physical connectivity, and Fibre Channel frame routing. Each FL_Port (and the embedded FL_Port) has a 24-bit address identifier. The address identifier is expressed in hexadecimal format as DD AA PP, where: • DD is the domain identifier. This identifier is assigned one of 31 values (60 through 7F). • AA is the area identifier. Each physical FL_Port (12 or 24 ports) is assigned one of up to 24 values (04 through 1B). • PP is the port identifier. Each device (node) attached to an FL_Port is assigned one of 126 AL_PA values (01 through EF). The embedded FL_Port is assigned an AL_PA of 00. Planning for Private Arbitrated Loop Connectivity Private arbitrated loop topology supports the clustering of isolated servers and storage subsystems into workgroup or departmental SANs. This topology is well-suited to small and mid-sized configurations where modest connectivity levels and high data transmission speeds are required. The topology also supports low-cost switching and connectivity in environments where the per-port cost of a switched fabric director is prohibitive. Private arbitrated loop topology: • Supports the connection of up to 126 NL devices per loop plus the switch's embedded FL_Port (127 connections). • Reduces connection costs by distributing the routing function through each loop port (loop functionality is a small addition to normal Fibre Channel port functionality). • Provides a fully-blocking architecture that allows a single connection between any pair of loop ports. Connections between a third loop port and busy ports are blocked until communication between the first connection pair ends. 3-10 McDATA Products in a SAN Environment - Planning Manual