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SONET and SDH are globally standardized technologies, more
widely deployed than dark fiber or WDM, and provide a protected
connection between two locations. SONET and SDH rings are also
self-healing. This means a link is usually restored within 50 ms of
break detection without user intervention. This makes SONET and
SDH highly-available services.
Generic Framing Procedure (GFP) is a protocol-independent SONET
and SDH standard that defines a mapping scheme for storage
protocols such as native FCP, FICON, and iFCP. The standard
includes a forward error-correction scheme that enables low bit-error
rates critical for storage connectivity. Additionally, the protocol
mapping to SONET or SDH requires little overhead and has minimal
impact on latency and throughput. GFP is deployed with virtual
concatenation (VCAT), a standard that increases bandwidth
efficiency by flexibly extending bandwidth allocation in 50-Mbps
increments. This extends the bandwidth range from 50 Mbps to full
Fibre Channel rates. To support storage extension over long
distances, GFP provides buffering and flow control to ensure high
throughput without the need for Fibre Channel BB_Credit buffering.
Figure 4-10
through a SONET interface.
Figure 4-10
SONET Extended-Distance Connectivity
The technology:
•
Is widely deployed and highly-available, and is well suited as an
extension technology for ADR applications over thousands of
kilometers.
illustrates multiple extended-distance connections
Implementing SAN Internetworking Solutions
Implementing SAN Internetworking Solutions
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