Technical data

12-2 Fabric OS Administrator’s Guide
Publication Number: 53-0000518-09
Standard Trunking Criteria
12
Figure 12-1 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. Cable lengths for participating links should differ by no more than 550 meters. For optimal
performance, no more than 30 meters difference is recommended.
Connections between SilkWorm 4100 and SilkWorm 48000 (using FC4-16 and FC4-32 port blades)
models support these advanced features:
• Up to eight ports in one trunk group to create high performance 32-Gbit/sec 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 Gbit/sec trunk links
The maximum number of ports per trunk and trunks per switch depends on the SilkWorm model.
For detailed information about trunking commands, refer to online help or the Fabric OS Command
Reference Manual.
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 Gbit/sec or 4 Gbit/sec).
• Trunk ports must be set to the same ISL mode (L0 is the default). For details on extended ISL
modes, refer to Table 11-1 on page 11-3.
• Trunk ports must be E_Ports.
• Cable lengths for participating links should differ by no more than 550 meters.
• The switch.interopMode parameter must be set to 0. Refer to “Configuring Interoperability Mode”
on page B-1 for information and procedures related to interoperability mode.
• The port ISL mode must be disabled (using the portCfgIslMode command).