FW 05.01.00 and SW 07.01.00 HP StorageWorks SAN High Availability Planning Guide (AA-RS2DC-TE, June 2003)

Planning Considerations for Fibre Channel Topologies
74 SAN High Availability Planning Guide
The switch B_Port provides a single 1.0625 Gbps ISL to an E_Port on a director
or edge switch. Direct ISL connectivity between loop switches (with or without a
redundant B_Port connection to a director or edge switch) is generally not
supported. However, a director or edge switch does support the connection of
multiple, independent switches. Figure 31 shows a configuration of two loop
switches attached to a director.
Figure 31: Arbitrated loop to switched fabric connectivity
Consider the following when planning arbitrated loop-to-switched fabric
connectivity and incorporating FC-AL devices into the enterprise SAN
environment:
■ B_Port traffic is routed through a user-transparent FL_Port that is embedded
on the switch’s control processor (CTP) card. Switch mode (shared or
switched) has no impact on B_Port operation. However, because all
switch-attached FC-AL devices must arbitrate for access to the embedded
FL_Port, loop performance issues (loop round-trip time, number of loop
tenancies, service rate, and loop utilization) must be evaluated.