HP StorageWorks 2/140 FW 08.01.00 McDATA Products in a SAN Environment Plannin - Page 210
Extended-Distance Ports, High-Availability Considerations, Existing cable restrictions
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Physical Planning Considerations 5 • Existing cable restrictions - The enterprise may contain only one type of fiber-optic cable (multimode or singlemode), and the customer may be required to use the existing cables. Customers may also be required to use existing copper cables for some arbitrated loop devices. Extended-Distance Ports Through longwave laser transceivers and repeaters or wavelength division multiplexing (WDM) equipment, directors and fabric switches support Fibre Channel data transmission distances of over 100 km. The extended distance feature is enabled on a port-by-port basis by using entries in the RX BB Credit column for a specified port at the Element Manager application's Configure Ports dialog box. This feature provides extended distance support using Fibre Channel protocol. Refer to Distance Extension Through BB_Credit for additional information. When a director or fabric switch port is configured to support extended link distances, the attached device (or attached fabric element) must also support extended distance operation and be configured to use a higher BB_Credit value to maintain link efficiency. If the extended distance feature is enabled for a port that is not installed or does not support extended distance operation, the configuration for the feature is ignored. High-Availability Considerations To provide high device availability, critical servers, storage devices, or applications should be connected to more than one fabric element (director or switch) or to more than one fabric. To determine if dual-connection capability exists for a device, refer to the associated device documentation. To provide high fabric availability, consider the use of multiple fabric elements (directors and switches), multiple ISLs, or redundant fabrics. Refer to Fabric Availability for information. Plan to maintain unused (spare) director and switch ports if port connections must be quickly moved and re-established after a failure. If an individual port or an entire port card fails, optical transceivers or port cards can be removed and replaced, spare port connections identified (through the Element Manager application), and fiber-optic cables rerouted and reconnected while the director or switch is operational. 5-6 McDATA Products in a SAN Environment - Planning Manual
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