CCIE commands with detailed explanations for each command in its specific topic set. These commands can help you when troubleshooting specific technologies and where to find certain information.

Basic Commands

show version – displays basic information about the router in terms of how long it has been up, the amount of flash and DRAM in the router, the interface controllers setup, the hardware platform and the IOS version. Also the ROM bootstrap version.

show controllers – displays detailed hardware information about the cabling attached to the interface. It will give info if the cable is attached, the clock rate speed, and the cable type.

show flash – displays the contents of the flash, in terms of the file name, the amount of the flash and how much is left.

show ip route – displays the routing table of all best possible routes.

show interfaces – displays all of the interfaces with information about its MAC address (the LAN interface), the primary IP address configured, any input/output errors on the interface, the encapsulation types, and other info.

show ip interface brief – displays a quick list of all the interfaces including whether they are up/active, there primary IP address, and info about the line protocol as well. Good tool for troubleshooting.

debug tftp – displays detailed information about all UDP/69 traffic passing on the network.

show tech-support – displays a complete summary of the majority of the commands, such as “show run”, “show ver”, “show hardware”, “show buffer”, “show process cpu”, “show process memory”, “show interfaces”, “show controllers”.

show buffer – displays information about all of buffer levels and there settings.

show process cpu >sort< – displays all main CPU processes or service running on the router, and the percentage that is being utilized.

show process memory >sort< – displays almost the same information as the “show process cpu” command. It will focus on more about which service is utilizing the most memory allocation.

show running-config – displays the current active configuration from the DRAM. Which is the temp. memory source.

show startup-config – displays the configuration in the NVRAM, which is the perm. memory source.

(config)# alias exec|configure – configure aliases to shorten commands like:

alias exec sr show run – typing sr will execute show run
alias exec srr sh run | b ^router – srr shows running config starting at the routing protocols

alias configure all-int int range f0/1 - 24 , g0/1 - 2 –
when in config mode executing all-int will let exual entering range mode for all interfaces (3524XL with 2x GE), this is nice for setting all interfaces to switchport mode access and other generic interface statements. Chaning vlan assignments is also nice with ranges as all interfaces will change simultaneously reducing down time and excessive error messages.

Frame Relay Commands

show frame-relay lmi – displays lmi information between the router and the frame relay switch.

show frame-relay map – displays frame relay static or dynamic routes configured on the DTE router.

show frame-relay pvc – displays about the routers pvc circuit, including info about the routers local dlci and whether it is active or deleted.

show frame-relay route – displays information about the route entries from the frame relay switch it is connected to.

debug frame packet – display frame relay traffic going through the router.

debug frame lmi – displays lmi transactions between the frame relay switch and the local DTE router.

show interface serial – displays basic information on the interface in terms of what encapsulation is setup, including (frame-relay) DCE/DTE information plus LMI types set up.

Terminal, Session or Console Server Commands

show line – displays information about the specific line setup, whether it is for telnet, console, and the async (aux) line.

debug modem – displays information about the exec process and the modem process whether it is active or any error messages.

show sessions – displays which sessions are currently open on the router.

show users all – displays all information about which session or terminal sessions are open whether it is telnet, console, or through the aux port.

Distance Vector Routing Commands

show ip route – displays the routing table and the best routes to a specific destination.

show ip protocols – displays specific routing protocol information in terms of update timers, holdtimes, invalid/flush timers, plus any filtering configured for the routing protocol and/or its interface.

show ip route rip – displays the routing table, showing all rip routes in the routing table.

debug ip rip – displays information about rip routing including updates and any known errors.

clear ip route * – this clears the routing table and all static routes propagated.

debug ip igrp events – displays all igrp routing information and all known errors.

debug ip igrp transactions – displays the igrp information and all transactions.

show ip route igrp – displays the routing table, showing specific igrp routes in the table.

OSPF Commands

show ip ospf neighbor – displays ospf neighbour routers it is connected to, displaying info on the initial ospf state (full, 2-way), the router ID, and other stuff.

show ip ospf database – displays the routing table of the entire network.

show ip ospf interface – displays ospf parameters configured on the interface; showing area ID, hello/dead timers, network types, and its router ID of the OSPF area network.

show ip route ospf – displays ospf routes in the current routing table.

show ip protocol – displays information about the specific configured routing protocols in terms of hold down timers, when the hello packets will be sent out next, plus info on any outbound or inbound filtering for the routing protocol, ospf, or the configured interface.

debug ip ospf adj – displays detailed information about the ospf connected neighbors, focusing on whether hello packets are being sent out on the network, or if there are any known errors like hello/dead interval mismatches.

show ip ospf virtual-links – displays information about the configured virtual links configured on the router and/or the routers in the currently area.

show ip ospf – displays specific ospf information in terms of the timers and other SPF alg. properties send out.

debug ip ospf packet – displays detailed ospf packet information that are sent to/from, plus giving out any other potential errors detected.

debug ip ospf events – displays ospf information in terms of the SPF calculations, flooding information, plus info from the Designated Router, and the ospf neighbor routers.

EIGRP Commands

show ip route eigrp – displays eigrp routes configured in the routing table.

show ip eigrp neighbors – displays eigrp neighbouring routers configured in the AS EIGRP network.

show ip eigrp topology – displays the entire routing table of the EIGRP network, including all successor and feasible routes as well.

show ip eigrp interface – displays EIGRP information configured on the interface, in terms of hello/dead times, plus other info.

show ip eigrp traffic – displays all EIGRP traffic in terms of packets being sent and/or received.

debug eigrp packet – displays detailed EIGRP routing information sent in the EIGRP network and all hello/messages exchanging updates of there neighbor tables.

debug eigrp fsm – displays detailed information about EIGRP feasible successor routes traveling within the EIGRP network when the successor route is no longer available.

debug ip eigrp – displays EIGRP information

BGP Commands

show ip bgp – displays BGP routes configured and shows all possible routes to destination for BGP configured. It shows the best path depending on the AS PATH selection, Local Preference, MED (metric), or based on the highest selection with the weight.

show ip bgp summary – displays all BGP route connections. Very similar to the command “show ip bgp”.

clear ip bgp * – when bgp routes are changed or updated, the BGP table should be cleared, otherwise synchronization should be disabled on the IGP router.

show ip bgp neighbor – displays all of BGP connected and configured neighbors depending on its IP and AS number.

debug ip bgp – displays detailed BGP routing and update information.

show ip bgp filter-list – displays detailed BGP information in terms of what filtering is being blocked out or being permitted within many AS networks.

Catalyst LAN Switching Commands

show port – displays information about the specific port on the switch, giving such information as if the port is connected or not. The speed, duplex setup, spanning tree mode, the vlan group, MAC address. (e.g. “show port 5/11”)

show module – displays information about the specific module or blade in the unit, in terms of whether it is active and/or standby mode or disabled. It will also give information in terms of all of the ports at once including a summary of its connectivity. It will also show what “show version” has to offer in terms of hardware/software/firmware versions.

show interface – displays the same information as the show interface of a router. In this case it will show information like the IP address, vlan group, MAC address, its status on the SUP module or blade.

show spantree – displays all spanning tree information such as who is the root, and specific spanning tree modes (listening, learning, forwarding, and blocking; depending which port is setup as a root or designated port)

show vlan – displays information about all of the vlans configured on the switch, including info such as which VLANs are active and which port is part of which VLAN. (ISR built in switch vlan config: show vlan-switch)
show vtp domain – displays virtual terminal protocol information which mode it is (server, client, transparent), and the current name of the VTP domain. (Old: show vtp status)
show cam dynamic – displays the current MAC address database where the source MAC addresses were stored when they were trying to find a destination MAC address machine. That information is automatically saved and will be seen in the CAM table, which is almost similar to the routing table on a router.

clear config all – this will erase all of the configuration on the switch show ip permit – display all information all which IP address or IP block has access into the switch.

show trunk – displays all information about trunking and whether it is enabled. It will also show which vlans will be trunked.

show system – displays basic information about the system name, location, and contact name. show version – displays basic information what the hardware modules, including firmware and software versions. Also other info serial numbers for each module, info about the flash memory.

show mac – displays detailed MAC information in terms of traffic passing through. It won’t give you MAC address information, that info can be found by doing a “show module”.

HSRP Commands

show standby – displays all HSRP configuration on the router including its standby group number, whether it is the active master or in standby mode. It will display info about standby timers, priority, and the virtual MAC and IP addresses.

debug standby – displays detailed information about the convergence process of hsrp process whether the master goes down and the standby becomes active.

Policy Based Routing Commands

show ip policy – displays basic information on which interface the policy based routing is configured on and the route-map that is attached to it.

debug ip policy – displays policy routing information on whether the policy has been routed or rejected.

ISDN and Dialer Commands (removed from R&S per 1 jan 2006)

show isdn status – displays isdn bri information in regards to all of the three layers. Verifying if the circuit is active (layer 1), if the right TEIs are assigned to the B channels with the proper spids (layer 2), and if there is any active successful calls (layer 3).

show dialer – displays dialer information on layer 3, with information about whether the calls received were successful or failed. Information with the dialer string, and the B channels in terms of the reasoning for initializing the dialer link and if the channel is in idle mode.

show ppp multilink – displays PPP multilink information on supplying which B channels are member links of the MLPPP group. You can also verify whether the MLPPP is open by doing a “show interface bri 0/0:1 or :2” display the B channels.

show interface bri 0/0 – displays information about the D channel, which should be up and be spoofing.

show interface bri 0/0:1 – displays information about B channel one, which will be down until an actual layer 3 call is dialed. It will also show MLPPP information as well, whether it is open or closed.

show interface bri 0/0:2 – displays information about B channel two, which should be down until an actual call is placed. It will also show MLPPP connection whether it is open or closed.

debug ppp authentication – displays detailed information about the PPP authentication whether it is CHAP or PAP. It will show if the password is correct or invalid.

debug isdn q921 – displays detailed information about the D channel on layer 2.

debug isdn q931 – displays detailed information about the D channel on layer 3, and the call process.

show isdn service – displays ISDN PRI information on the call process, and information about one of the 24 channels are either idle or busy.

show controller t1/e1 – displays information about the T1/E1 circuit in terms of the line coding and the framing bits.

ATM Commands (removed from R&S per 1 jan 2006)

show interface atm – displays information about the interface encapsulation type and what ATM Adaptation Layer it is on, the VC type whether it is PVC or SVC. Also basic information whether it is in loopback mode or not.

show atm vc – displays PVC information that was configured under the atm interface. Specifying VPI and VCI information, including whether the VC is active or not. It will supply other information as the cell burst as well.

show atm traffic – displays incoming and outgoing packets on the router through the ATM network/interface.

show atm map – displays ATM dynamic and static routes configured on the ATM interface mapping the ATM VC number and the destination IP address of the destination router/location.

show controllers atm – displays ATM information about the fiber or copper cable connected to the interface port and if it is functionally and active.

debug atm packet – displays detailed information about ATM cells coming in and out. Important for testing whether packets or cells are being received from another router plus if information is coming out as well.

CDP Commands

show cdp interfaces – displays all of the interfaces that are configured with cdp, also other information like the cdp timer settings.

show cdp neighbors – displays all connected devices seen by the cdp. Giving such information as the device type, the port, and device name.

show cdp traffic – displays cdp packet information coming in and out of the router.

debug cdp packets – displays detailed cdp events and information, plus any known errors.

NAT Commands

show ip nat translations – displays all addresses translated on the router.

show ip nat translations verbose – same as the “show ip nat translations” just for detailed information.

show ip nat statistics – displays info on what was configured in terms of the pool name, the translating address range plus netmask. The inside and outside interfaces, plus how much is being allocated.

debug ip nat – displays detailed info about the packets being translated from a private address to public address.

clear ip nat statistics – clear all translating IP address on the router and all statistics.