Fcp And Ficon In A Single Fabric - HP StorageWorks 64 - SAN Director Switch Planning Manual

Planning Considerations for Fibre Channel Topologies
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However, fabric initialization is not a serial process. The process executes
concurrently across all ISLs in the fabric, causing a massive flood of Class F
traffic that must processed to the embedded port of each fabric element within a
specified (fabric-wide) error detect time- out value (E_D_TOV). If the fabric
consists of a large number of elements (and therefore ISLs), Class F traffic may
not be processed within the E_D_TOV, resulting in error recovery operations,
timeouts, segmented links, or fabric failure.
Because of these problems, a fabric with a high ISL count is more difficult to
build. Note that the fabric problem is not directly related to the large number of
fabric elements, but to the large number of ISLs associated with the elements.
Fabric build concerns currently limit the combined number of directors and
switches to about 24.

FCP and FICON in a Single Fabric

Fibre Channel Layer 4 (FC-4) describes the interface between Fibre Channel and
various upper-level protocols. FCP and FICON are the major FC-4 protocols. FCP
is the Fibre Channel protocol that supports the small computer system interface
(SCSI) upper-level transport protocol. FICON is the IBM successor to the
enterprise systems connection (ESCON) protocol, and adds increased reliability
and integrity to that provided by the FCP protocol.
Because FCP and FICON are both FC-4 protocols, routing of Fibre Channel
frames is not affected when the protocols are mixed in a single fabric
environment. However, management differences in the protocols arise when a user
changes director or edge switch parameters through zoning or connectivity
control. In particular:
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Employ a routing protocol to establish the shortest path through the fabric and
program route tables for each fabric element.
Exchange the active zone set to ensure uniform zoning is enforced between all
fabric elements.
FCP communication parameters are port number and name-centric, discovery
oriented, and assigned by the fabric, and they use the Fibre Channel name
server to control device communication.
FICON communication parameters are logical port address-centric, definition
oriented, and assigned by the attached host, and they use host assignment to
control device communication.
SAN High Availability Planning Guide