Troubleshooting Trunking Problems; Listing Link Characteristics; Recognizing Buffer Underallocation; Getting Out Of Buffer-Limited Mode On E_Ports Or Ld_Ports - HP A7533A - Brocade 4Gb SAN Switch Base User Manual

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
where port specifies the number of a port in an ISL trunking group.
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 Gbit/sec or 4 Gbit/sec.
• 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 LD 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.
The following example shows that port 3 is not configured as an E_Port:
switch:admin> trunkdebug 3 5
port 3 is not E port
switch:admin>

Recognizing buffer underallocation

For the SAN Switch 2/8V, 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 others can operate using the
available buffers. (Standard trunks are not affected by buffer allocation.)
This issue of buffer underallocation does not apply to the SAN Switch 4/32 and 4/256 SAN Director.
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. Wait for
stabilization, and then correct the buffer allocation situation.

Getting 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).
174 Administering ISL trunking