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
58 SAN High Availability Planning Guide
Fibre Channel Topologies
The Director 2/64, Director 2/140, Edge Switch 2/16, Edge Switch 2/24, and Edge
Switch 2/32 support point-to-point and multi-switch fabric topologies, and
indirectly support arbitrated loop topology. A combination of these topologies
(hybrid topology) is also supported.
Related HP switches support switched mode and traditional (shared mode)
arbitrated loop topologies, and indirectly support a switched fabric topology.
These topologies are described as follows:
■ Point-to-point — This topology provides a single direct connection between
two device node ports (N_Ports), and supports bidirectional transmission
between the source and destination ports. Through dynamic switching, a
director or edge switch configures different point-to-point transmission paths.
In all cases, connected N_Ports use 100% of the available bandwidth. For
additional information, refer to “Planning for Point-to-Point Connectivity” on
page 59.
■ Arbitrated loop — This topology uses arbitrated loop switches (offered by
HP but not described in this publication) to connect multiple device node loop
ports (NL_Ports) in an FC-AL or hub configuration without benefit of a
multiswitch fabric. The following modes of operation are supported:
— Switched mode topology provides a single, logical connection between
two device NL_Ports. The switch dynamically configures different logical
transmission paths, and in all cases, connected NL_Ports have access to
100% of the available bandwidth.
— Shared mode arbitrated loop topology connects multiple device NL_Ports
in a hub (or star) configuration without benefit of a switched fabric. The
switch supports connection of up to 125 arbitrated loop devices and
cascaded hubs.
Although directors and edge switches do not support direct connection of
arbitrated loop devices, the loop devices can communicate with fabric
elements through and arbitrated loop switch bridge port (B_Port). If
peripheral loop devices are expected to communicate with fabric-attached
devices, consider installation of a loop switch (with a director or edge switch)
to form a fabric-loop hybrid topology. For additional information, refer to
“Characteristics of Arbitrated Loop Operation” on page 60, “Planning for
Private Arbitrated Loop Connectivity” on page 66, and “Planning for
Fabric-Attached Loop Connectivity” on page 73.