VTSS Configuration Planning
FICON Data Transfer Rates
The fastest native FICON channels are rated at 200 MB/sec., but actually can achieve a maximum data rate of only 170 MB/sec. under optimum conditions. In actual practice, FI- CON typically operates at 40-60 MB/sec. using the 32 KB block size commonly found in tape workloads.
VCF3 cards support 2 Gb link speeds; actual throughput speed is determined by many factors including block size, microcode level, etc.
FICON Cabling — Short-Wave vs. Long-Wave Connections
Currently, FICON channels send data via fiber-optic cables only; copper-wire cables are not supported. Fiber-optic data communiction cables are either single-mode or multi- mode, as summarized in Table 2-5, and have these characteristics:
•Single-mode cables have a smaller core size than multi-mode, typically 8.5 or 9 microns, and use long wavelengths to transmit data over greater distances (up to 10 km; 20 km with an RPQ)1
•Multi-mode cables have a larger core size than single-mode cables, typically 50 or 62.5 microns, and use short wavelengths, which limits transmission range to distances less than 500 m (1640 ft.). Multi-mode cables are more economical when long transmission distances are not a requirement.
VCF2 (FICON) cards support both short- and long-wave connections through different SFP connectors, which can be intermixed on individual cards. By default, VCF2 cards ship with long-wave (LX) SFP connectors; an orderable option allows field upgrades to short- wave (SX) connections.
LC Fibre connectors are used on both short- and long-wave SFPs, which requires use of LC-LC or LC-SC cables for all VTSS-to-host connections.
Table 2-5. Single-Mode vs. Multi-Mode FICON Cabling
| Mode Type | Core Size | Wavelength | Color | Max. Transmission Distance | Relative Cost |
| Single-mode | 8.5 to 9 | | | • 10 km (6.2 mi.) | |
| Long (LX) | Yellow | • 20 km (12.4 mi.) with RPQ | More |
| (SM) | microns |
| | | • 100 km (62 mi.) with repeaters | |
| | | | | |
| | | | | | |
| Multi-mode | 50 to 62.5 | Short (SX) | Orange | • 50 micron: ≤500 m (1640 ft.) | Less |
| (MM) | microns | ≤ |
| | | | | • 62.5 micron: 175 m (574 ft.)* | |
Note: * Requires mode-conditioner patch (MCP) cables, used in pairs. Data rates >100 MB/sec. are not supported when MCP cables are used.
1. RPQ is not available with FICON channels rated at 200 MB/sec.
