HP Mainframe Connectivity Design Guide

2 FICON SAN fabric topologies
This chapter discusses HP FICON SAN fabric topologies. The terms FICON director and FICON
switch are used interchangeably. The terms director and switch refer to a FICON director-class
product and a FICON switch-class product, respectively.
Fabric topologies
A FICON fabric is a single-switch fabric or a cascaded fabric. Single-switch and cascaded refer
to the number of directors in the data path, not the actual number of directors in the fabric.
A FICON fabric has a maximum of one hop between the mainframe channel and the CU, or
between two mainframe channels, using CTC. A maximum of two FICON directors are allowed
in the path. Additional directors are allowed in the same fabric (up to the maximum allowed by
the director series), with the one-hop maximum.
In addition to the information presented in this chapter, FICON fabrics must comply with the SAN
design rules described in the following chapters:
• “B-series FICON directors and fabric rules” (page 29)
• “C-series FICON directors and fabric rules” (page 46)
• “McDATA FICON directors and fabric rules” (page 63)
• “Mainframe rules” (page 86)
• “P9500 storage system rules” (page 103)
• “XP storage system rules” (page 110)
A SAN fabric topology defines the arrangement of FICON directors in a fabric. HP supports the
following SAN fabric topologies to meet your data access and connectivity requirements:
• Single-switch FICON fabric
• Cascaded FICON fabric
Regardless of which topology you use, the following general rules apply to all FICON SANs:
• FICON CHPIDs can be directly attached to storage (point-to-point) or can be attached through
a FICON SAN.
• All FICON mainframes support point-to-point and single-switch fabric configurations. zSeries,
z9, or z10 processors are required for cascaded fabrics (one-hop ISLs). See “Mainframe
rules” (page 86).
• Multiple FICON directors can be configured in the same fabric, as long as the routing maintains
the one-hop maximum between the mainframe channel and the CU.
• In general, B-series FICON directors are supported only with other B-series or Brocade directors.
However, certain B-series directors can coexist in the same fabric as certain McDATA directors.
See “B-series FICON directors and fabric rules” (page 29).
• C-series FICON directors are supported only with other C-series or Cisco directors. See “C-series
FICON directors and fabric rules” (page 46).
• In general, McDATA FICON directors are supported only with other McDATA directors.
However, certain McDATA directors can coexist in the same fabric as certain B-series directors.
See “McDATA FICON directors and fabric rules” (page 63).
Single-switch FICON fabric
A single-switch fabric is the simplest FICON SAN design. It consists of a FICON director, mainframe,
and storage system as shown in Figure 1 (page 16). In a single-switch fabric, there are no ISLs in
the data path from the mainframe to the storage system.
Fabric topologies 15