Managing long-distance fabrics, Long-distance fabrics overview, Managing long-distance – Brocade Fabric OS Administrators Guide (Supporting Fabric OS v7.3.0) User Manual
Page 527: Fabrics
Managing Long-Distance Fabrics
Long-distance fabrics overview
The most effective configuration for implementing long-distance SAN fabrics is to deploy Fibre Channel
switches at each location in the SAN. Each switch handles local interconnectivity and multiplexes traffic
across long-distance dark fiber or wave-length division multiplexing (WDM) links, while the Brocade
Extended Fabrics software enables SAN management over long distances.
Brocade Extended Fabrics is an optional licensed feature for Brocade SAN deployment over distances
beyond 10 km. A Brocade Extended Fabrics license is required before you can implement long-distance
dynamic (LD) and long-distance static (LS) distance levels. The LD and LS settings are necessary to
achieve maximum performance results over inter-switch links (ISLs) that are greater than 10 km.
For details about obtaining and installing licensed features, refer to the Fabric OS Software Licensing
Guide.
The Extended Fabrics feature enables the following functionality:
• Fabric interconnectivity over Fibre Channel at longer distances
ISLs can use long-distance dark fiber connections to transfer data. Wavelength-division multiplexing,
such as dense wavelength-division multiplexing (DWDM), coarse wavelength-division multiplexing
(CWDM), and time-division multiplexing (TDM), can be used to increase the capacity of the links. As
Fibre Channel speeds increase, the maximum distance decreases for each switch.
The Extended Fabrics feature extends the distance the ISLs can reach over an extended fiber. This
extension is accomplished by providing enough buffer credits on each side of the link to compensate for
latency introduced by the extended distance.
• Simplified management over distance
Each device attached to the SAN appears as a local device, which simplifies deployment and
administration.
• Optimized switch buffering
When Extended Fabrics is installed on gateway switches (with E_Port connectivity from one switch to
another), the ISLs (E_Ports) are configured with a large pool of buffer credits. The enhanced switch
buffers help ensure that data transfer can occur at near-full bandwidth to use the connection over the
extended links efficiently. This efficiency ensures the highest possible performance on ISLs.
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