.Part 4 SAN Extension and Bridging HP SAN Design Reference Guide 785354-001

FC-SONET IP link configurations
Using FC-SONET, you can configure the SANs through a single link, dual links, or shared ISL links.
FC-SONET dual-link configuration
A dual-link configuration is the benchmark for disaster protection (Figure 93 (page 271)). If one link
fails, the other link temporarily handles all data replication. For enhanced fault tolerance, you use
two IP providers, accessing the data center through two links.
Figure 93 FC-SONET dual-link configuration
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In a dual-link configuration, HP recommends that you limit the maximum sustained I/O load to
40% of the maximum available bandwidth for each link. This allows for instantaneous bursts of
I/O activity and minimizes the effect of a link failure on performance.
FC-SONET shared-link configuration
A shared-link configuration uses only one ISL between fabrics (Figure 94 (page 271)).
Figure 94 FC-SONET shared-link configuration
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NOTE: Do not use the shared-link configuration if you require high availability because it does
not provide redundancy between fabrics. It can also decrease performance because the total
bandwidth available for storage is shared by the two fabrics.
FC-SONET network considerations
Implementing FC-SONET with your existing network depends on the expected storage replication
application load and existing network traffic. The key consideration is whether you have enough
unused or available bandwidth from your network to support the current network load, accommodate
future growth, and handle replication load demands.
HP supports the use of SONET with HP P9000 (XP) Continuous Access. See “ATM and SONET/SDH”
(page 311).
Third-party SONET gateways
For a list of HP-certified third-party SONET gateways, see “Certified third-party WDM, iFCP, and
SONET products” (page 317).
Multi-protocol long-distance technology 271