Белая книга для Cisco Cisco ACE Application Control Engine Module
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Monitoring Data Plane Use
The following command provides a good indication of the load of the network processor cores in terms of packet
and connection processing:
ACE/Admin# show np # -cpu | beg Util
ME % Utilization Statistics
--------------
Core 0: 3
Core 1: 0
Core 2: 0
Core 3: 0
Core 4: 0
Core 5: 0
Core 6: 0
Core 7: 0
Core 8: 0
Core 9: 0
Core 10: 0
Core 11: 0
Core 12: 0
Core 13: 0
Core 14: 0
Core 15: 0
Note: All show np commands must be run for each of the network processors (one network processor in Cisco
ACE 4710 and one to four network processors in the Cisco ACE30 Module). This output must be combined for all
network processors on the device to calculate the total load.
The network processor cores operate safely at any percentage of utilization. A network processor core that
approaches 100 percent utilization is an indication that the traffic load is stressing its limit. Any core that reaches
100 percent utilization can cause backpressure and may lead to dropped packets or, in the worst case, dropped
connections.
Monitoring Backpressure
Backpressure occurs when a bottleneck develops as traffic performance is increased. Backpressure is the
mechanism used to slow down the system when queues start to fill up internally because a microengine is reaching
its peak utilization. This scenario can occur when incoming traffic exceeds the capacity of the Cisco ACE. As
backpressure builds, the first-in, first-out (FIFO) queue for the CDE and internal queues for each data-plane
function in the network processor cores can become filled. A sustained period of time in which the Cisco ACE is
running at or above capacity can lead to overflows and dropped packets. When the Cisco ACE reaches capacity,
new packets are dropped, though not necessarily entire connections. However, if the overflow continues,
connections may be dropped by clients and servers.
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To monitor the CDE queues on the Cisco ACE module, use the show cde health command and verify that
Fifo Full drop count is not incrementing.