HP StorageWorks 2/16V HP StorageWorks Fabric OS 5.X Procedures User Guide (AA- - Page 168

Standard trunking criteria, Fabric considerations, Evaluate the traffic patterns within the fabric.

Page 168 highlights

The maximum number of ports per trunk and trunks per switch depends on the HP StorageWorks model. For detailed information about trunking commands, see online help or the HP StorageWorks Fabric OS 5.x command reference guide. Standard trunking criteria Observe the following criteria for standard distance trunking: • There must be a direct connection between participating switches. • Trunk ports must reside in the same port group. • Trunk ports must run at the same speed (either 2 Gbit/sec or 4 Gbit/sec). • Trunk ports must be set to the same ISL mode (L0 is the default). For details on extended ISL modes, see Table 30 on page 164. • Trunk ports must be E_Ports. • Cable lengths for participating links should differ by no more than 550 meters. • The switch.interopMode parameter must be set to 0. See "Configuring interoperability mode" on page 229 for information and procedures related to interoperability mode. • The port ISL mode must be disabled (using the portCfgIslMode command). Fabric considerations The ISL trunking feature is provided with the Fabric OS and can be activated by entering a license key, available from the switch supplier. When the ISL Trunking license is activated (after you have entered the switchDisable and switchEnable commands), trunking is implemented for any eligible ISLs. A license must be activated on each switch that participates in trunking. For the Core Switch 2/64, a single license key enables the feature on both logical switches. To use ISL trunking in the fabric, the fabric must be designed to allow trunking groups to form. To identify the most useful trunking groups, evaluate the traffic patterns before designing or redesigning the fabric. This also applies to the SAN Director 2/128 configured with two domains, and the 4/256 SAN Director, which does not support two domains. ISL Trunking can be used to simplify SAN design and improve performance. When designing the SAN, consider the following recommendations in addition to the standard guidelines for SAN design: • Evaluate the traffic patterns within the fabric. • Place trunking-capable switches adjacent to each other. This maximizes the number of trunking groups that can form. If you are using a core/edge topology, place trunking-capable switches at the core of the fabric and place any switches that are not trunking-capable at the edge of the fabric. • Activate an ISL Trunking license on each switch that is to participate in a trunking group. • Cable lengths for participating links should differ by no more than 550 meters. • When connecting two switches with two or more ISLs, ensure that all trunking requirements are met to allow a trunking group to form. • Determine the optimal number of trunking groups between each set of linked switches, depending on traffic patterns and port availability. The goal is to avoid traffic congestion without unnecessarily using ports that could be used to attach other switches or devices. Consider these points: • Each physical ISL uses two ports that could otherwise be used to attach node devices or other switches. • Trunking groups can be used to resolve ISL oversubscription if the total capability of the trunking group is not exceeded. 168 Administering ISL trunking

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168
Administering ISL trunking
The maximum number of ports per trunk and trunks per switch depends on the HP StorageWorks model.
For detailed information about trunking commands, see online help or the
HP StorageWorks Fabric OS
5.x command reference guide
.
Standard trunking criteria
Observe the following criteria for standard distance trunking:
There must be a direct connection between participating switches.
Trunk ports must reside in the same port group.
Trunk ports must run at the same speed (either 2 Gbit/sec or 4 Gbit/sec).
Trunk ports must be set to the same ISL mode (L0 is the default). For details on extended ISL modes, see
Table 30
on page 164.
Trunk ports must be E_Ports.
Cable lengths for participating links should differ by no more than 550 meters.
The
switch.interopMode
parameter must be set to 0. See ”
Configuring interoperability mode
” on
page 229 for information and procedures related to interoperability mode.
The port ISL mode must be disabled (using the
portCfgIslMode
command).
Fabric considerations
The ISL trunking feature is provided with the Fabric OS and can be activated by entering a license key,
available from the switch supplier. When the ISL Trunking license is activated (after you have entered the
switchDisable
and
switchEnable
commands), trunking is implemented for any eligible ISLs.
A license must be activated on each switch that participates in trunking. For the Core Switch 2/64, a
single license key enables the feature on both logical switches.
To use ISL trunking in the fabric, the fabric must be designed to allow trunking groups to form. To identify
the most useful trunking groups, evaluate the traffic patterns before designing or redesigning the fabric.
This also applies to the SAN Director 2/128 configured with two domains, and the 4/256 SAN Director,
which does not support two domains.
ISL Trunking can be used to simplify SAN design and improve performance. When designing the SAN,
consider the following recommendations in addition to the standard guidelines for SAN design:
Evaluate the traffic patterns within the fabric.
Place trunking-capable switches adjacent to each other.
This maximizes the number of trunking groups that can form. If you are using a core/edge topology,
place trunking-capable switches at the core of the fabric and place any switches that are not
trunking-capable at the edge of the fabric.
Activate an ISL Trunking license on each switch that is to participate in a trunking group.
Cable lengths for participating links should differ by no more than 550 meters.
When connecting two switches with two or more ISLs, ensure that all trunking requirements are met to
allow a trunking group to form.
Determine the optimal number of trunking groups between each set of linked switches, depending on
traffic patterns and port availability.
The goal is to avoid traffic congestion without unnecessarily using ports that could be used to attach
other switches or devices. Consider these points:
Each physical ISL uses two ports that could otherwise be used to attach node devices or other
switches.
Trunking groups can be used to resolve ISL oversubscription if the total capability of the trunking
group is not exceeded.