19Administering Isl Trunking; About Isl Trunking; Distribution Of Traffic Over Isl Trunking Groups - HP A7533A - Brocade 4Gb SAN Switch Base Administrator's Manual

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
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- 1 6/32/48, FC4- 1 6IP, and the DC SAN Backbone Director
(short name, DC Director) using the FC8- 1 6/32/48 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.
"Enter the information in the required fields." on page 35. Trunking is enabled
Fabric OS 6.x administrator guide 373