HP StorageWorks Fabric OS 6.1.x administrator guide (5697-0234, November 2009)

Fabric OS 6.1.x administrator guide 357
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. ISL trunking is
extended to N_Ports where trunks are formed when the edge switch is running Fabric OS 6.1.x or later.
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 38 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 38 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, 400 MP
Router, 8/8 SAN Switch, 8/24 SAN Switch, 8/40 SAN Switch, 8/80 SAN Switch
and the 4/256 SAN
Director using the FC4-16/32/48, FC4-16IP, FC8-16/32/48, the FR4-18i blades,and the DC SAN
Backbone Director (short name, DC Director) using the FC8-16/32/48 and the FR4-18i blades support
these advanced features:
• Up to eight ports in one trunk group to create high performance 32 Gbps ISL trunks between switches
and up to 64 Gbps if there are eight ISLs with 8 Gbps each if 8 Gbps is supported.
• ISL Trunking over longer distances than other platforms.
• 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.