HP Brocade 4Gb SAN Switch for HP BladeSystem p-Class - Manual (Page 120)

120 Administering ISL trunking
Troubleshooting trunking problems
If you have difficulty with trunking, try the solutions in this section.
Listing link characteristics
If a link that is part of an ISL Trunk fails, use the
trunkdebug
command to troubleshoot the problem,
as shown in the following procedure:
1. Connect to the switch and log in as admin.
2. Issue the following command:
trunkdebug port, port
The
trunkdebug
command displays the possible reason that two ports cannot be trunked, including the
following reasons:
• The switch does not support trunking.
• A trunking license is required.
• Trunking is not supported in switch interoperability mode.
• Port trunking is disabled.
• The port is not an E_Port.
• The port is not 2 Gbps or 4 Gbps.
• The port connects to different switches.
• The ports are not same speed, or they are not set to a valid speed.
• The ports are not set to the same long-distance mode.
• Local or remote ports are not in same port group.
• The difference in the cable length among trunked links is greater than the allowed difference.
This example shows that port 3 is not configured as an E_Port:
Recognizing buffer underallocation
For the SAN Switch 2/16V, SAN Switch 2/32, Core Switch 2/64, and SAN Director 2/128, if there is
an underallocation or overcommitment of buffers to ports configured for extended trunking, the switches at
both ends of the trunk try to disable some ports so that others can operate using the available buffers.
(Standard trunks are not affected by buffer allocation.) This issue does not apply to the SAN Switch 4/32.
A port disabled at one end causes all the disabled ports at the other end to become enabled. Some of
these enabled ports become disabled due to a lack of buffers, which in turn triggers ports to be enabled
once again at the other end. While the system is stabilizing the buffer allocation, it warns that ports are
disabled due to lack of buffers, but it does not send a message to the console when buffers are enabled.
The system requires a few passes to stabilize the buffer allocation. Ultimately, the number of ports for
where
port
specifies the number of a port in an ISL Trunking group.
switch:admin> trunkdebug 3 5
port 3 is not E port
switch:admin>