HP AE370A HP StorageWorks Fabric OS 6.x administrator guide (5697-0015, May 20 - Page 373

19 Administering ISL Trunking This chapter contains procedures for using the ISL Trunking licensed feature, which optimizes the use of bandwidth by allowing a group of interswitch links to merge into a single logical link. About ISL Trunking ISL Trunking reduces or eliminates situations that require static traffic routes and individual ISL management to achieve optimal performance. Trunking optimizes fabric performance by distributing traffic across the shared bandwidth of all the interswitch links in a trunking group, allowing traffic to flow through any available link in a group rather than restricting it to a specific, potentially congested link. The use of trunking results in simplified fabric design and management, lowered cost of ownership, and increased data availability. To use trunking, you must first install the ISL Trunking license. For details on obtaining and installing licensed features, see "Enter the information in the required fields." on page 35. Trunking is enabled automatically when the ISL Trunking license is activated and ports are reinitialized (after installing the license, you enter the switchDisable and switchEnable commands), and trunks are easily managed using either Fabric OS CLI commands or Web Tools. You can enable and disable trunking and set trunk port speeds (for example, 2 Gbps, 4 Gbps, 8 Gbps, or autonegotiate) for entire switches or for individual ports. Trunks distribute traffic dynamically and in order at the frame level, achieving greater performance with fewer interswitch links. Trunks are compatible with both short wavelength (SWL) and long wavelength (LWL) fiber optic cables and transceivers. Figure 30 illustrates how trunking can result in more throughput by distributing data over four ISLs with no congestion. In a fabric that does not have trunking capability, some paths would be congested and other paths under-utilized. Figure 30 Distribution of traffic over ISL Trunking groups Trunks operate best when the cable length of each trunked link is roughly equal to the others in the trunk. For optimal performance, no more than 30 meters difference is recommended. Connections between the HP StorageWorks SAN Switch 4/32, 4/32B, 4/64 SAN Switch, Multi-protocol Router, the 4/256 SAN Director using the FC4-16/32/48, FC4-16IP, and the DC SAN Backbone Director (short name, DC Director) using the FC8-16/32/48 port blades support these advanced features: • Up to eight ports in one trunk group to create high performance 32 Gbps 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 Gbps trunk links. • 8 Gbps trunk links where supported. Fabric OS 6.x administrator guide 373