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

20 Administering ISL trunking

ISL Trunking overview

This chapter contains procedures for using the B-Series Inter-Switch Link (ISL) Trunking licensed feature,
which optimizes the use of bandwidth by allowing a group of inter-switch links to merge into a single
logical link.
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 inter-switch 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 6.2.0 or later.
To use trunking, you must first install the ISL Trunking license. For details on obtaining and installing
licensed features, see Chapter 1,
automatically when the ISL Trunking license is activated and ports are reinitialized. 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. You can enable and disable trunking and set trunk port
speeds (for example, 2 Gb/s, 4 Gb/s, 8 Gb/s, or autonegotiate) for entire switches or for individual
ports.
Trunks distribute traffic dynamically and in order at the frame level, thus achieving greater performance
with fewer inter-switch links.
Trunks are compatible with both short wavelength (SWL) and long wavelength (LWL) fiber optic cables and
transceivers.
Figure 74 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 underutilized.
Figure 74

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 HP StorageWorks SAN Switch 4/32, HP StorageWorks 4/64 SAN Switch, HP
StorageWorks 400 Multi-Protocol Router, HP StorageWorks 8/40 SAN Switch, HP StorageWorks 8/80
SAN Switch, HP StorageWorks 8/8 and 8/24 SAN Switches, Brocade 4Gb SAN Switch for HP c-Class
BladeSystem, the HP StorageWorks 4/256 SAN Director using the HP StorageWorks 4/256 SAN Director
16 Port 4Gb Blade, HP StorageWorks 4/256 SAN Director 32 Port 4Gb Blade, HP StorageWorks SAN
Director 48 Port 4Gb FC blade, HP StorageWorks B-Series iSCSI Director Blade, HP StorageWorks SAN
Director 16 Port 8Gb FC blade, HP StorageWorks SAN Director 32 Port 8Gb FC blade, HP StorageWorks
4/256 SAN Director 48 4Gb Blade, B-Series Multi-Protocol Router Blade, the HP StorageWorks DC SAN
Backbone Director using the HP StorageWorks SAN Director 16 Port 8Gb FC blade, HP StorageWorks
SAN Director 32 Port 8Gb FC blade, HP StorageWorks SAN Director 48 Port 8Gb FC blade and the
"Performing basic configuration tasks" on page 29. Trunking is enabled
Fabric OS 6.2 administrator guide 435