HP StorageWorks 8/80 HP StorageWorks Fabric OS 6.1.x administrator guide (5697 - Page 358

• 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. • 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 "Implementing an Interoperable Fabric" on page 505 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 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. The trunking groups are based on the user port number with contiguous eight ports as one group, such as, 0-7, 8-15 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 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. • Consider how the addition of a new path will affect existing traffic patterns: • A trunking group has the same link cost as the master ISL of the group, regardless of the number of ISLs in the group. This allows slave ISLs to be added or removed without causing data to be rerouted, because the link cost remains constant. • The addition of a path that is shorter than existing paths causes traffic to be rerouted through that path. 358 Administering ISL Trunking