HP Mainframe Connectivity Design Guide

The configuration in Figure 27 (page 135) costs more, but is fully redundant.
Figure 27 Fully redundant WDM configuration using two long-distance fiber optic links
WDM
connection
WDM
connection
25145a
Fabric A1
Local
Fabric A1
Remote
Fabric B1
Local
Fabric B1
Remote
HP recommends that you use multiple fiber links between the two FICON directors in a FICON
extension or FICON SAN extension. This provides redundancy in the event of a fiber link or WDM
component failure. The fiber links should be on separate paths in case there is a cable failure.
HP supports the following third-party WDM products and configurations:
• CWDM and DWDM systems supported by the director vendors.
• WDM devices that are configurable to a data rate of 1 Gb/s, 2 Gb/s, 4 Gb/s, 8 Gb/s, or
10 Gb/s.
• Up to 300 km for FICON extension or FICON SAN extension over a WDM link (director-model
dependent). Some FICON directors may experience reduced performance at this distance.
Distances greater than 100 km may require an approved IBM RPQ.
Performance levels depend on the number of buffers available in the FICON director and the
volume of data.
For information about HP-certified third-party WDM products, see “Certified third-party WDM and
FCIP products” (page 152).
Extended fabric settings for FICON directors
When using extended fabrics with FICON directors that have long-distance transceivers or WDM,
it is important to maintain the performance of ISL connections. This section describes the FICON
director settings that enhance performance over extended ISLs. An extended ISL is greater than 10
km at 1, 2, 4, 8, or 10 Gb/s.
The longer the ISL is between two communicating devices, the more BB_credits are required to
maintain data throughput. As the ISL speed increases, more BB_credits are required. Table 84 (page
135) lists the BB_credit values for different ISL speeds. These values apply to all FICON director
models when extending ISLs with long-distance transceivers or WDM products.
Table 84 BB_credit guidelines
Minimum number of
nl
Minimum number of
nl
ISL speed BB_credits for a 100 km ISLBB_credits for a 1 km ISL
500.51 Gb/s
10012 Gb/s
20024 Gb/s
40048 Gb/s
600610 Gb/s
800816 Gb/s
FICON long-distance technology 135