HP AE370A - Brocade 4Gb SAN Switch 4/12 Administrator'S Manual Download

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334 Administering ISL Trunking

Connections between SAN Switch 4/32, 4/64 SAN Switch, and 4/256 SAN Director (using FC4-16 and

FC4-32 port blades) models support these advanced features:

•

Up to eight ports in one trunk group to create high performance 32-Gbit/sec ISL trunks between

switches

•

ISL Trunking over longer distances than other models

•

Dynamic trunk master reassignment if a trunk master is disabled (on other platforms, all ports on a trunk

must be disabled temporarily to reassign a master)

•

4 Gbit/sec trunk links

The maximum number of ports per trunk and trunks per switch depends on the HP StorageWorks model.
For detailed information about trunking commands, refer to online help or the

Fabric OS Command

Reference Manual

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,

refer to

Table 38

on page 232.

•

Trunk ports must be E_Ports.

•

For optimal performance, no more than 30 meters difference is recommended.

•

The

switch.interopMode

parameter must be set to 0.

•

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 automatically implemented for any

eligible ISLs.
A license must be activated on each switch that participates in trunking.
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 storage area network 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 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.

•

For optimal performance, no more than 30 meters difference is recommended.

•

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