Terminal Monitor

terminal monitor - turns on terminal monitoring
terminal no monitor - turns off terminal monitoring

Debug

show debug (displays all current debug operations)
debug ip routing (displays routing related events)
debug ip rip (displays rip routing events when enabled)
debug ip ospf events (displays OSPF activity when enabled on a router)
debug all (DANGEROUS - but turns on all debugging on Cisco IOS)

Router Platform

show running-config
show startup-config
show clock (displays current time setting)
show history (displays a history of input IOS commands)
show diag (displays hardware information)
show interface (displays all interface information)
show ip interface {brief} (displays information about installed ip interfaces)
show ip arp (displays entire ARP table)
show version (lots of info on IOS version, interfaces, memory and more)
show protocols (displays what protocols are currently running)
show process (displays all running processes on the platform)
show memory (displays current memory usage)
show buffers (displays packet buffer allocation and utilization)
show ip traffic (displays a summary of IP traffic statistics)
show access-list (shows the all the currently configured access-lists, but it also shows you the number of hits each line has received)
show users (displays who is currently logged on/configuring the router)
show processes - shows active processes running on router
show memory - shows memory statistics
show flash - describes the flash memory and displays the size of files and the amount of free flash memory
show buffers - displays statistics for router buffer pools; shows the size of the Small, Middle, Big, Very Big, Large and Huge Buffers
show stacks - shows reason for last reboot, monitors the stack use of processes and interrupts routines
show port - similar to the show interface command on routers, this command gives you the status of ports on a switch.
show vlan - use this command to make sure your ports are in the VLANs you think they are. Its output is very well designed.
show tech-support - this command is great for collecting a lot of info. It basically runs a whole bunch of other show commands, and spits out dozens of pages of detailed output, designed to be sent to technical support. But, it's also useful for other purposes.

Cisco Discovery Protocol (CDP)

show cdp neighbors {detail} (if CDP is enabled, this is a quick way to display what neighbors exist on which interfaces - must all be Cisco devices)
show cdp interfaces - shows which interfaces are running CDP
show cdp entry - shows CDP neighbor detail
cdp timer 120 - change how often CDP info is sent (default cdp timer is 60)
cdp holdtime 240 - how long to wait before removing a CDP neighbor (default CDP holdtime is 180)
show cdp run - shows if CDP turned on
no cdp run - turns off CDP for entire router (global config)
no cdp enable - turns off CDP on specific interface

TCP

show ip socket
show tcp brief
show tcp tcb (number from tcp above)

Basic IP Routing

show ip protocols
show ip route {summary}
show ip cef {detail}

BGP

show ip bgp neighbor {address}
show ip bgp summary

MPLS

show mpls interfaces
show mpls ip bindings
show mpls forwarding-table {detail}

LDP

show mpls ldp parameters
show mpls ldp neighbor {detail}
show mpls ldp discovery
show mpls ldp bindings

MPLS DEBUG

debug mpls ldp ...
debug mpls lfib ...
debug mpls packets {interface}

MPLS L3VPNs

ping vrf {vrfname} {ipaddress}
traceroute vrf {vrfname} {address}
telnet {address} /vrf {vrfname}

VRF

show ip vrf {detail}
show ip vrf interfaces
show ip protocol vrf {vrfname}
show ip route vrf {vrfname}
show ip cef vrf {vrfname}
show mpls forwarding vfr {vrfname} {address} {detail}

MBGP

show ip bgp vpnv4 all summary
show ip bgp vpnv4 vrf {vrfname} {iproute}
show ip bgp vpnv4 rd {rd number} summary
show ip bgp vpnv4 rd {rd number} neighbors {address} routes
show ip bgp vpnv4 rd {rd number} tags
show ip bgp neighbor x.x.x.x advertised-routes
show ip bgp recieved-routes

Clearing and Resetting Commands

clear ip route * (clears the ip route tables and causes the routing adjancencies to be reestablished)
clear ip bgp * (clears the BGP routing tables and resets the adjacencies)
clear count {interface} (clears the QoS and traffic counters on the specified interface)

Important Editing keys

backspace or delete key (deletes one character to the left of the CLI cursor position)
crtl-d (deletes one character to the right of the CLI cursor position)
ctrl-b or left arrow (moves cursor to the left on character)
ctrl-f or right arrow (moves cursor to the right one word)
ctrl-shift-6 (break operation - i.e. when ping is hung up)
esc-b (moves cursor to the left one word)
esc-f (moves cursor to the right one word)
ctrl-a (moves cursor to the beginning of a line)
ctrl-e (moves cursor to the end of a line)

We hope you like this cheat sheet!

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