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UNCLASSIFIED Implementing Security on Cisco Routers  Version 1.0g  UNCLASSIFIED 137        0 Trap PDUs SNMP logging: disabled Central#                   The only way to clear these statistics is to reset the router. Router Debug Commands  Cisco IOS offers a very extensive suite of debugging commands.  Each debugging command is associated with a particular service, facility, or feature of the router.   When debugging is enabled for a particular protocol or feature, all activities of that protocol or feature will generate log messages at level 7.    Debug messages, when generated, are sent to all log sources configured to receive them.  The number of messages generated by debugging can often be quite large.   Therefore, when using the debug messages for interactive troubleshooting, be sure to configure the buffered log and syslog for level 6 (informational).  The example below shows how to configure debugging, and turn on debugging messages for ICMP. Central# show users     Line     User      Host(s)                  Idle Location *130 vty 0   rscg      idle                 00:00:00 14.2.9.6 Central# config t Enter configuration commands, one per line.  End with CNTL/Z. Central(config)# logging console information Central(config)# logging monitor debug Central(config)# logging buffered information Central(config)# logging trap information Central(config)# exit Central# Mar 3 17:01:58.159 EST: %SYS-5-CONFIG_I: Configured from console by nziring on vty0 (14.2.9.6) Central# term monitor Central# debug ip icmp ICMP packet debugging is on Central# ! At this point, “ping central” was performed on 14.2.9.6 Mar 3 17:02:13 EST: ICMP: echo reply sent, src 14.2.9.250, dst 14.2.9.6 Central# no debug ip icmp ICMP packet debugging is off Central#                                    The Cisco documentation set includes a volume with comprehensive information about the debug facilities and their behavior, the Cisco IOS Debug Command Reference.