Sun Microsystems 96257 FICON Data Transfer Rates, 5. Single-Mode vs. Multi-Mode FICON Cabling

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.

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	Revision A