Standard Trunking Criteria; Fabric Considerations - HP A7533A - Brocade 4Gb SAN Switch Base Administrator's Manual

• 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 Gbps trunk links.
• 8 Gbps trunk links where supported.
The maximum number of ports per trunk and trunks per switch depends on the HP model.
NOTE: Director blade model FC10-6 does not support trunking.

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 Gbps, 4 Gbps, or 8 Gbps).
• Trunk ports must be set to the same ISL mode (L0 is the default). For details on extended ISL mode see
Table 77 on page 366.
• Trunk ports must be E_Ports or EX_Ports and F_Ports if using Access Gateway.
In Fabric OS 5.2.0 and later, you can configure EX_Ports to use frame-based trunking just like regular
E_Ports. EX_Port frame-based trunking has a master trunk link. If the master link goes down, the entire
trunk re-forms and is taken offline for a short period of time. The EX_Port restrictions are the same as
E_Ports. An E_Port or EX_Port trunk can be up to eight ports wide. All the ports must be adjacent to
each other using the clearly marked groups on the front of the product.
The switch.interopMode parameter must be set to 0. See
•
on page 245 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 can be activated by entering a license key, which is available from HP. After the
ISL Trunking license is activated (after you have issued 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. The trunking groups are based on the user port number with
contiguous eight ports as one group, such as, 0-7, 8- 1 5 and 16-23.
To identify the most useful trunking groups, consider the following recommendations along with 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.
• 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 the following:
• 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.
• Consider how the addition of a new path will affect existing traffic patterns:
368 Administering ISL trunking
"Implementing an interoperable fabric"