Cisco common debug/troubleshooting commands

debug dhcp

SW#debug ip dhcp server packet
SW#debug ip dhcp server events
SW#show ip dhcp binding
SW#show ip dhcp server statistics

mst spanning-tree

SW250#show spanning-tree mst
SW250#show spanning-tree mst 1
SW250#show spanning-tree mst configuration
SW250(config)#spanning-tree mst configuration
SW250(config-mst)#no instance 1
SW250(config-mst)#instance 1 vlan 100-200

#### Exit to save msg configuration
SW250(config-mst)#exit

#### Set this SW as vtp primary server
SW250#vtp primary mst

“MST region is not configurable as the system is not the primary server for MST database”

#### To set vtp primary server, you MUST be in priv exec
SW250#vtp primary mst
SW250# show vtp status

routing

R1#show ip protocols
R1#show ip protocols | sec ospf
R1#show ip protocols | sec bgp
R1#show ip protocols | sec Sources
R1#show ip protocols | sec filter


R1#show key chain

rip with authentication

R1#debug ip rip
R1#undebug all

SW(config)#key chain TWO_HUNDRED
SW(config-keychain)#key 1
SW(config-keychain-key)#key-string Cisco
SW(config)#int vlan 200
SW(config-if)#ip rip authentication key-chain TWO_HUNDRED
SW#show run | sec router rip
SW(config)#router rip
SW(config-router)#no passive-interface vlan 200
DSW1(config-router)#no auto-summary
SW#show ip protocols | i summ

VRRP

R1#show vrrp
R1#show track 2
R1#show ip sla summary
R1#show ip protocols
R1#show ip protocols | i filter
R1#show ip prefix-list
R1#show ip prefix-list SW2
R1(config)#no ip prefix-list SW2

ipv6 neighbors

R1#show ipv6 route
R1#show ipv6 eigrp neighbors
R1#show ipv6 eigrp interfaces
R1#show ipv6 neighbors
R1#show ipv6 traffic
R1#show ipv6 int | i is up
R1#show access-lists paranoia
R1(config)#ipv6 access-list paranoia
R1(config-ipv6-acl)#permit ipv6 any any
R1#show ipv6 ospf neighbor
R1#show ipv6 ospf interface brief
R1#debug ipv6 ospf hello
R1#undebug all
R1(config)#int range gi1/x, gi2/x, gi3/x
R1(config-if)#ipv6 ospf network point-to-point
R1(config-if)#ipv6 ospf network broadcast
R1#show ipv6 ospf database router adv-router 3.3.3.3
R1#show ipv6 ospf database link adv-router 2.2.2.2
R1#show ipv6 ospf database router adv-router 2.2.2.2

SNMP

R2#debug snmp packets

EIGRP

#debug eigrp packets query detail reply detail

OSPF

R#debug ip ospf hello
R#debug ip ospf lsa-generation

NTP

### debug on client to see time unable to synchronize
R#debug ntp packet

HSRP

SW2# debug standby terse
SW2# undebug all

STP

SW1# debug spanning-tree events

Debug with access-list xx (source 5.5.5.5)

R5(config)#access-list xx permit 5.5.5.5
R5#debug ip packet xx