HP ProCurve 5400zl Switch Series - High CPU Utilization (99-100%) after Startup
Issue
Right after the switch is started, high (99-100%) CPU utilization is
observed. Solution
When the switch boots, one of the initialization tasks is creation of
encryption keys. Having the keys created in advance means that later,
when a feature such as SSL or SSH that uses the keys is configured or
used, there is minimal delay in the availability. This task takes a
few seconds before it ramps up, depending on the switch model, the
configuration being loaded, and the software revision. Even though the
task consumes up to 100% of the CPU, it runs at a very low priority.
Therefore, if another task requiring CPU cycles is started, this low
priority task will back off. If this initialization/key generation
task runs uninterrupted by higher priority tasks, it takes about 10
minutes to complete. If the CPU is busy with other tasks, the
completion time will be extended.
To verify that the elevated CPU being seen is in fact what has been
described here and not something else that requires troubleshooting,
please use the commands documented below.
task-monitor cpu (this command was introduced in K.13.04)
show uptime
show cpu
The output will look like the following.
Switch# task-monitor cpu Switch# show uptime 0000:00:01:42.36 Switch#
show cpu
99 percent busy, from 27 sec ago
1 sec ave: 100 percent busy
5 sec ave: 100 percent busy
1 min ave: 66 percent busy
Task usage for last 5 sec
% CPU | Description
-------+--------------------------
0.3 | Sessions & I/O
99.7 | System Services
Best Answer
Yes, configure it, just because your port channel is good doesn't mean your entire topology necessarily is - just connect another cable between the two switches on an active VLAN and watch the badness happen.
I recommend MST (Multiple Spanning Tree) providing the switch supports it - interoperable, backwards compatible and of course, has the obvious benefit of being able to partition vlans into separate domains.