FW V06.XX/HAFM SW V08.02.00 HP StorageWorks SAN High Availability Planning Guide (AA-RS2DD-TE, July 2004)

Table Of Contents
Planning Considerations for Fibre Channel Topologies
124 SAN High Availability Planning Guide
FICON Cascading
The initial FICON architecture did not permit connection of multiple directors or
switches, because the protocol specified a single byte for the link (port) address
definition in the input-output configuration program (IOCP). The link address
only defined the Port_ID for a unique domain (director or switch).
The current FICON architecture provides two-byte addressing that allows the
IOCP to specify link (port) addresses for any number of domains by including the
domain address with the Port_ID. FICON fabrics can now be configured using
multiple director and switches (FICON cascading). In a cascaded FICON
environment, at least three Fibre Channel links are involved:
The first link is between the FICON channel card (N_Port) of an IBM eServer
zSeries processor and a director or switch F_Port.
The second link is an ISL between two director or switch E_Ports.
The final link is from a director or switch F_Port to a FICON adapter card
(control unit N_Port) in a storage device, tape device, or other peripheral.
These Fibre Channel links connect FICON fabric elements and provide a physical
transmission path between a channel and control unit. Users may configure
multiple ISLs between cascaded FICON directors or switches to ensure
redundancy and adequate bandwidth.
High-Integrity Fabrics
Cascaded FICON directors and switches must support high-integrity fabrics.
Fabric elements must have the SANtegrity Binding feature installed and
operational with Enterprise Fabric Mode enabled. High-integrity fabric
architecture support includes:
Fabric binding — Only directors or switches with fabric binding installed
are allowed to attach to specified fabrics in a SAN. Specifically:
Fabric elements without a SANtegrity Binding feature key are prohibited
from connecting to fabric elements with an active SANtegrity Binding
feature key.
Inherent to directors and switches with an active SANtegrity Binding
feature key is a fabric membership list (comprised of acceptable WWNs
and domain IDs) of the elements logged into the fabric. This membership
list is exchanged between fabric elements, and an element with an