3. Troubleshooting Functional Failures in Operation1263.23 Communication Failure Caused by Settings ofFiltering/QoS3.23.1 Checking Filtering/QoS Setting InformationAs a cause for communication failure on the network using this system, certain packets may have been discarded byfiltering or packets may have been discarded through bandwidth monitoring, discarding control, or shaper of the QoScontrol.If packets are discarded within this system by filtering or QoS control, the procedure for identifying the discardinglocation is described below.(1) Checking packet discarding by filtering1. Log in to the system.2. Check the filtering conditions of the access list applied to the interface, the number of packets meeting the filteringconditions, and the number of packets discarded according to implicit discarding filter entry by using the showaccess-filter command.3. Compare the filtering conditions identified in step 2 and the contents of the packet that cannot be exchanged, and seeif the packets have been discarded. If the packets that cannot be exchanged do not meet all of the filtering conditionsapplied, the packets in this example, may have been implicitly discarded.4. Review to see if setting conditions in filtering configuration are correct.(2) Checking packet discarding through bandwidth monitoring of QoS control1. Log in to the system.2. Check the flow detecting condition and operation designation of bandwidth monitoring applied to the interface andthe number of packets meeting the flow detecting conditions by executing the show qos-flow command.3. Compare the flow detecting conditions identified in step 2 and the contents of the packet that cannot be exchanged,and see if the packets have been discarded. The packets which violate maximum bandwidth control are discarded,and "matched packets (max-rate over)" statistical information is incremented. If this statistical information isincremented, packets may be discarded through bandwidth monitoring applied to the interface.4. Review to see if setting conditions in QoS control configuration are correct and bandwidth monitoring settings insystem configuration are proper.(3) Checking packet discarding through discarding control and shaper of QoS controlIP8800/S6700, IP8800/S6600, and IP8800/S63001. Log in to the system.2. Check the "discard_pkt"statistical information of the port sending/receiving queue for the input interface andoutput interface used for communication by using the show qos queueing command with "interface"parameter specified.3. Check the "discard_pkt"statistical information of the distribution sending/receiving queue for accommodatingthe input interface or output interface used for communication by using the show qos queueing commandwith "distribution" parameter specified.4. If the statistical information identified in steps 2 and 3 is incremented, packets are discarded through discardingcontrol of QoS control.5. Review to see if discard control and shaper have been set up appropriately for the system operation.
