The Cisco IOS CLI show commands display relevant information about the configuration and operation of the device. Network technicians use show commands extensively for viewing configuration files, checking the status of device interfaces and processes, and verifying the device operational status. The status of nearly every process or function of the router can be displayed using a show command.
Commonly used show commands and when to use them are listed in Table 18-6.
Table 18-6 IOS show Commands
| Command | Used to |
| show running-config | Verify the current configuration and settings. |
| show interfaces | Verify the interface status and see if there are any error messages. |
| show ip interface | Verify the Layer 3 information of an interface. |
| show arp | Verify the list of known hosts on the local Ethernet LANs. |
| show ip route | Verify the Layer 3 routing information. |
| show protocols | Verify which protocols are operational. |
| show version | Verify the memory, interfaces, and licenses of the device. |
Examples 18-2 through 18-8 display the output from each of these show commands.
Example 18-2 show running-config
R1# show running-config
(Output omitted)
!
version 15.5
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname R1
!
interface GigabitEthernet0/0/0
description Link to R2
ip address 209.165.200.225 255.255.255.252
negotiation auto
!
interface GigabitEthernet0/0/1
description Link to LAN
ip address 192.168.10.1 255.255.255.0
negotiation auto
!
router ospf 10
network 192.168.10.0 0.0.0.255 area 0
network 209.165.200.224 0.0.0.3 area 0
!
banner motd ^C Authorized access only! ^C
!
line con 0
password 7 14141B180F0B
login
line vty 0 4
password 7 00071A150754
login
transport input telnet ssh
!
end
R1#
R1# show interfaces
GigabitEthernet0/0/0 is up, line protocol is up
Hardware is ISR4321-2x1GE, address is a0e0.af0d.e140 (bia a0e0.af0d.e140)
Description: Link to R2
Internet address is 209.165.200.225/30
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not supported
Full Duplex, 100Mbps, link type is auto, media type is RJ45
output flow-control is off, input flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:00:21, output hang never
Last clearing of “show interface” counters never
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
5127 packets input, 590285 bytes, 0 no buffer
Received 29 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 5043 multicast, 0 pause input
1150 packets output, 153999 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
1 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out
Example 18-4 show ip interface
R1#
show ip interface
GigabitEthernet0/0/0 is up, line protocol is up
Internet address is 209.165.200.225/30
Broadcast address is 255.255.255.255
Address determined by setup command
MTU is 1500 bytes
Helper address is not set
Directed broadcast forwarding is disabled
Multicast reserved groups joined: 224.0.0.5 224.0.0.6
Outgoing Common access list is not set
Outgoing access list is not set
Inbound Common access list is not set
Inbound access list is not set
Proxy ARP is enabled
Local Proxy ARP is disabled
Security level is default
Split horizon is enabled
ICMP redirects are always sent
ICMP unreachables are always sent
ICMP mask replies are never sent
IP fast switching is enabled
IP Flow switching is disabled
IP CEF switching is enabled
IP CEF switching turbo vector
IP Null turbo vector
Associated unicast routing topologies:
Topology “base”, operation state is UP
IP multicast fast switching is enabled
IP multicast distributed fast switching is disabled
IP route-cache flags are Fast, CEF
Router Discovery is disabled
IP output packet accounting is disabled
IP access violation accounting is disabled
TCP/IP header compression is disabled
RTP/IP header compression is disabled
Probe proxy name replies are disabled
Policy routing is disabled
Network address translation is disabled
BGP Policy Mapping is disabled
Input features: MCI Check
IPv4 WCCP Redirect outbound is disabled
IPv4 WCCP Redirect inbound is disabled
IPv4 WCCP Redirect exclude is disabled
(Output omitted)
R1#
show arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 192.168.10.1 – a0e0.af0d.e141 ARPA GigabitEthernet0/0/1
Internet 192.168.10.10 95 c07b.bcc4.a9c0 ARPA GigabitEthernet0/0/1
Internet 209.165.200.225 – a0e0.af0d.e140 ARPA GigabitEthernet0/0/0
Internet 209.165.200.226 138 a03d.6fe1.9d90 ARPA GigabitEthernet0/0/0
R1#
R1#
show ip route
Codes: L – local, C – connected, S – static, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route, H – NHRP, l – LISP
a – application route
+ – replicated route, % – next hop override, p – overrides from PfR
Gateway of last resort is 209.165.200.226 to network 0.0.0.0
O*E2 0.0.0.0/0 [110/1] via 209.165.200.226, 02:19:50, GigabitEthernet0/0/0
10.0.0.0/24 is subnetted, 1 subnets
O 10.1.1.0 [110/3] via 209.165.200.226, 02:05:42, GigabitEthernet0/0/0
192.168.10.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.10.0/24 is directly connected, GigabitEthernet0/0/1
L 192.168.10.1/32 is directly connected, GigabitEthernet0/0/1
209.165.200.0/24 is variably subnetted, 3 subnets, 2 masks
C 209.165.200.224/30 is directly connected, GigabitEthernet0/0/0
L 209.165.200.225/32 is directly connected, GigabitEthernet0/0/0
O 209.165.200.228/30 [110/2] via 209.165.200.226, 02:07:19,
GigabitEthernet0/0/0
R1#
R1#
show protocols
Global values:
Internet Protocol routing is enabled
GigabitEthernet0/0/0 is up, line protocol is up
Internet address is 209.165.200.225/30
GigabitEthernet0/0/1 is up, line protocol is up
Internet address is 192.168.10.1/24
Serial0/1/0 is down, line protocol is down
Serial0/1/1 is down, line protocol is down
GigabitEthernet0 is administratively down, line protocol is down
R1#
R1#
show version
Cisco IOS XE Software, Version 03.16.08.S – Extended Support Release
Cisco IOS Software, ISR Software (X86_64_LINUX_IOSD-UNIVERSALK9-M), Version
15.5(3)S8, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2018 by Cisco Systems, Inc.
Compiled Wed 08-Aug-18 10:48 by mcpre
(Output omitted)
ROM: IOS-XE ROMMON
R1 uptime is 2 hours, 25 minutes
Uptime for this control processor is 2 hours, 27 minutes
System returned to ROM by reload
System image file is “bootflash:/isr4300-universalk9.03.16.08.S.155-3.S8-ext.SPA.
bin”
Last reload reason: LocalSoft
(Output omitted)
Technology Package License Information:
—————————————————————–
Technology Technology-package Technology-package
Current Type Next reboot
——————————————————————
appxk9 appxk9 RightToUse appxk9
uck9 None None None
securityk9 securityk9 Permanent securityk9
ipbase ipbasek9 Permanent ipbasek9
cisco ISR4321/K9 (1RU) processor with 1647778K/6147K bytes of memory.
Processor board ID FLM2044W0LT
2 Gigabit Ethernet interfaces
2 Serial interfaces
32768K bytes of non-volatile configuration memory.
4194304K bytes of physical memory.
3207167K bytes of flash memory at bootflash:.
978928K bytes of USB flash at usb0:.
Configuration register is 0x2102
R1#
Packet Tracer—Use Cisco IOS Show Commands (18.3.3)
In this activity, you will explore some Cisco IOS show commands.
Summary (18.4)
The following is a summary of each topic in the chapter:
- Navigate the IOS—The Cisco IOS command-line interface (CLI) is a text-based program that enables you to enter and execute Cisco IOS commands to configure, monitor, and maintain Cisco devices. It can be used with either in-band or out-of-band management tasks. To initially configure a Cisco device, you establish a console connection and navigate through various command modes of the IOS CLI. The Cisco IOS modes use a hierarchical structure and are quite similar for both switches and routers. As a security feature, the Cisco IOS software separates management access into the following two command modes: User EXEC Mode and Privileged EXEC Mode.
- The Command Structure—Each IOS command has a specific format or syntax and can be executed only in the appropriate mode. The general syntax for a command is the command followed by any appropriate keywords and one or more arguments:
- Boldface text indicates commands and keywords.
- Italicized text indicates an argument for which the user provides the value.
- Square brackets [x] indicate an optional element.
- Braces {x} indicate a required element.
- Braces and vertical lines within square brackets [x {y | z}] indicate a required choice within an optional element.
The IOS CLI provides hotkeys (for example, tab, backspace, Ctrl-C, etc.) and shortcuts (for example, conf for configure). They make configuring, monitoring, and troubleshooting easier.
- View Device Information—A typical show command can provide information about the configuration, operation, and status of parts of a Cisco switch or router. Some of the more popular show commands are:
- show running-config
- show interfaces
- show arp
- show ip route
- show protocols
- show version