HP Surestore 64 FW 05.01.00 and SW 07.01.00 HP StorageWorks SAN High Availabil - Page 80

Factors to Consider When Implementing a Fabric Topology, Hop count

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Planning Considerations for Fibre Channel Topologies ■ Hop count - The Fibre Channel theoretical limit of ISL connections traversed (hop count) in a single path through the fabric is seven. The maximum hop count supported by a fabric is based on current design rules. For information, refer to http://h18000.www1.hp.com/products/storageworks/san/documentation.html or contact your local HP sales representative. Note: The hop count is equal to the number of ISL connections traversed in a single path, not the total number of ISL connections between devices. As shown in Figure 35 on page 78, the number of ISL connections between Switch S1 and S2 is 4, while the number of hops is 1. Factors to Consider When Implementing a Fabric Topology Director and switch-based fabrics offer scalable, high-performance, and highavailability connectivity solutions for the enterprise. To enable a multi-switch fabric, all fabric elements must be defined to the HAFM application, and must be physically cabled to form the requisite ISL connections. In addition, HP recommends that each director or switch in the fabric be assigned a unique preferred domain ID. When planning to implement a fabric topology, consider the following connectivity and cabling concepts: ■ Physical characteristics and performance objectives - Most enterprises have unique configurations determined by the characteristics of end devices, fabric elements, cost, and the installation's performance objectives (such as high data transfer rate or high availability). These factors, along with nondisruptive growth and service requirements, must be evaluated when planning an initial fabric. For additional information, refer to "Planning a Fibre Channel Fabric Topology" on page 97. 80 SAN High Availability Planning Guide

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Planning Considerations for Fibre Channel Topologies
80
SAN High Availability Planning Guide
Hop count
The Fibre Channel theoretical limit of ISL connections
traversed (hop count) in a single path through the fabric is seven. The
maximum hop count supported by a fabric is based on current design rules.
For information, refer to
or contact your local HP sales representative.
Note:
The hop count is equal to the number of ISL connections traversed in a single
path, not the total number of ISL connections between devices. As shown in
Figure 35
on page 78, the number of ISL connections between Switch
S
1
and
S
2
is 4, while the
number of hops is 1.
Factors to Consider When Implementing a Fabric Topology
Director and switch-based fabrics offer scalable, high-performance, and high-
availability connectivity solutions for the enterprise. To enable a multi-switch
fabric, all fabric elements must be defined to the
HAFM
application, and must be
physically cabled to form the requisite ISL connections. In addition, HP
recommends that each director or switch in the fabric be assigned a unique
preferred domain ID.
When planning to implement a fabric topology, consider the following
connectivity and cabling concepts:
Physical characteristics and performance objectives
Most enterprises
have unique configurations determined by the characteristics of end devices,
fabric elements, cost, and the installation’s performance objectives (such as
high data transfer rate or high availability). These factors, along with
nondisruptive growth and service requirements, must be evaluated when
planning an initial fabric. For additional information, refer to “
Planning a
Fibre Channel Fabric Topology
” on page 97.