HP StorageWorks Fabric OS 6.x administrator guide (5697-7344, March 2008)

386 Administering ISL Trunking
• Port trunking is disabled.
• The port is not an E_Port.
• The port is not 2 Gbps, 4 Gbps, or 8 Gbps.
• The port connects to different switches.
• The ports are not the 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 the 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:
switch:admin> trunkdebug 3 5
port 3 is not E port
Recognizing buffer underallocation
A port disabled at one end because of buffer underallocation 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 which buffers are available come up and stabilize. You should wait for
stabilization, and then proceed with correcting the buffer allocation situation.
To get out of buffer-limited mode on E_Ports or LD_Ports:
1. Change the LD/L1/L2/L0.5 port speed to a lower speed (of non-buffer limited ports).
2. Change the LD port’s estimated distance to a shorter distance (of non-buffer limited ports).
3. Change LD/L1/L2/L0.5 back to L0 (of non-buffer limited ports).
4. If you are in buffer-limited mode on the LD port, then increase the estimated distance.
5. Enable any of these changes on the buffer-limited port or switch by issuing the commands
portDisable and portEnable.
Reconfiguring a port to LD from another mode can result in the port being disabled for lack of buffers—this
does not apply to the SAN Switch 4/32, 4/32B and 4/256 SAN Director (using FC4-16 and FC4-32 port
blades).
If this happens:
• In Fabric OS 4.2.x, reconfigure the disabled LD port back to the original mode.
• In Fabric OS 4.4.0 and later, specify a slightly shorter distance for the desired_distance parameter in
the portCfgLongDistance command.