debug — global
This command enables debugging at the specified
level. Just about every configuration item within the IOS has a debug level associated with it. The
debug ? command gives you an extensive list that allows you to find the debug level that meets your needs.
Be careful in selecting your debug level; you can easily crash a busy router with the incorrect selection. For example,
debug ip packet might render a busy router useless until debugging is disabled. See Chapter 16 for more information on using
debug correctly. If you get in trouble, issue the command
undebug all, which disables all debug output.
Here is the output from
debug ip ?:
Router#debug ip ? bgp BGP information cache IP cache operations cgmp CGMP protocol activity dvmrp DVMRP protocol activity egp EGP information eigrp IP-EIGRP information error IP error debugging ftp FTP dialogue http HTTP connections icmp ICMP transactions igmp IGMP protocol activity igrp IGRP information mcache IP multicast cache operations mobile Mobility protocols mpacket IP multicast packet debugging mrouting IP multicast routing table activity ospf OSPF information packet General IP debugging and IPSO security transactions peer IP peer address activity pim PIM protocol activity policy Policy routing rip RIP protocol transactions routing Routing table events rsvp RSVP protocol activity sd Session Directory (SD) security IP security ...