Specifications

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McDATA Products in a SAN Environment - Planning Manual
Planning Considerations for Fibre Channel Topologies
FL_Port Connectivity
Sphereon 4000-series 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.