20 Imp Cisco Commands for Network Engineer/Network Administrator/Network Monitoring

1. Show Version

The show version command displays different information depending on the type of device you use. This command gives uptime, info about software and hardware and a few other details.

●IOS version

● System uptime

● Image filename

● Type of processor

● Amount of RAM

● Number of ports on the switch

● Amount of flash memory

● MAC address

● Serial number

1-a) Show version | in uptime

This command shows uptime of devices.

Example:-

core_1#show version | in uptime

core_1 uptime is 1 year, 23 weeks, 5 days, 3 hours, 22 minutes

2). Show Processes CPU history

➢ The show processes CPU command to display detailed CPU utilization statistics on these processes.

➢ The show processes memory command to show the amount of memory used.

2-a) Show processes CPU

The show processes CPU command displays information about the active processes in the router and their corresponding CPU utilization statistics. The following is a sample output of the show processes CPU command:

router#show processes cpu

CPU utilization for five seconds: 8%/4%; one minute: 6%; five minutes: 5%

PID Runtime(uS)   Invoked  uSecs    5Sec   1Min   5Min TTY Process

1         384     32789     11   0.00%  0.00%  0.00%   0 Load Meter

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2-b) Show processes cpu history Command

The show processes cpu history command displays in ASCII graphical form the total CPU usage on the router over a period of time: one minute, one hour, and 72 hours, displayed in increments of one second, one minute, and one hour, respectively. Maximum usage is measured and recorded every second; average usage is calculated on periods over one second.

router#show processes cpu history

2-c) The show processes memory Command:--

The show processes memory command displays information about the active processes in the router and the corresponding memory used. The following is a sample output of the show processes memory command:

Router#show processes memory

Total: 106206400, Used: 7479116, Free: 98727284

PID TTY  Allocated      Freed    Holding    Getbufs    Retbufs Process

0   0      81648       1808    6577644          0          0 *Init*

Note: Due to the way in which show processes memory sorted is implemented in certain Cisco routers and switches, some devices (such as the Cisco 7304) show the total value as the sum of the processor memory and IO memory, rather than the total of the processor memory as shown by show processes memory.

3). Show Clock:-

Cisco Unity Express uses the Network Time Protocol (NTP) server for clocking functions. Use the show clock detail command to display the Cisco Unity Express module clock status.

core_1#show clock

02:07:58.264 EDT Tue Jul 22 2014

4). Show Module:-

Output shows modules present in Slots of Switch

core_1#show module

Mod      Ports Card Type                                            Model                     Serial No.

--- ----- -------------------------------------- ------------------ -----------

3   48   SFM-capable 48 port 10/100/1000mb RJ45    WS-X6548-GE-TX     SAL1215M8P5

4   48 SFM-capable 48 port 10/100/1000mb RJ45    WS-X6548-GE-TX     SAL1115L9WA

5). Show History:-

The following is sample output from the show history command, which lists the commands the user has entered in mode for this session.

core_1#show history

show ip route

show history

show ip int br

sh history

sh mac address-table

show history

6). Show Inventory:-

To display the system inventory information for a NAM (Network Analysis Module) device, use the show inventory command.

This command is supported on all NAM platforms.

The show inventory command allows you to view the UDI for a NAM device. This identity information is stored in the NAM device's non-volatile memory.

• PID—Product identification (ID) number of the device

• VID—Version ID of the device. Displays as 0 if the version number is not available.

• SN—Serial number of the device

core_1#show inventory

NAME: "WS-C6513", DESCR: "Cisco Systems Catalyst 6500 13-slot Chassis System"

PID: WS-C6513          , VID:    , SN: SAL08332806

NAME: "WS-C6K-VTT 1", DESCR: "VTT FRU 1"

PID: WS-C6K-VTT        , VID:    , SN: SMT0828D793

NAME: "WS-C6K-VTT 2", DESCR: "VTT FRU 2"

PID: WS-C6K-VTT        , VID:    , SN: SMT0828E238

What are VTY ports?

VTY ports are virtual TTY ports, used to Telnet or SSH into the router over the network. You can use them to connect to the router to make configuration changes or check the status. Most routers have five VTY ports, numbered 0 to 4.

That means you can have up to five concurrent network admins configuring the router at one time. However, you can easily generate more VTY lines.

7). Show Users:-

core_1#show users

Line          User          Host(s)              Idle            Location

*  1 vty 0       abcd        idle                  00:00:00    10.159.100.23

Interface      User          Mode                Idle        Peer Address

core_1#show run | in user

username netadmin password 758475AD4554KI454

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8). Show Line:-

Lines on Cisco routers are physical async serial ports on the router (such as a terminal or modem), a virtual network connection, or another type of serial line on the router. To see which lines you have on your devices, use the show line command. Here's an example:

core_1#show line

Tty Typ         Tx/Rx    A   Modem  Roty  AccO  AccI   Uses   Noise  Overruns   Int

0 CTY                          -     -            -          -         -        0           0          0/0         -

  1 VTY                    -      -            -          -         -     1616       0           0/0         -

2 VTY                 -     -             -         -         -       357         0          0/0        -

3 VTY                          -     -             -         -         -        96          0          0/0        -

4 VTY                -    -             -          -        -        28          0          0/0        -

9). Show CDP neighbor:-

CDP will show only directly connected devices, or neighbors with Local interface & Remote Interface

core_1#show cdp neighbor

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID             Local Interface     Holdtme    Capability   Platform   Port ID

CISCO2960X     Gig 0/2          123         R S I        CISCO 2960X-Gi1 /0/1

10). Show IP interface brief:-

This command is great for showing up/down status of IP interfaces, as well as what the IP address is of each interface. This command displays a brief summary of the interfaces on a device.

Router#show ip interface brief

Interface                          IP-Address              OK ?        Method         Status                Protocol

GigabitEthernet0/0         10.130.12.140            YES         NVRAM          up                        up

GigabitEthernet0/1          unassigned              YES         NVRAM             up                       up

GigabitEthernet0/1.10    10.0.0.1        YES          NVRAM            up                        up

Loopback0                      10.0.0.20           YES         NVRAM            up                        up

11). Show ip protocol summary:-

This command will show you all the current routing protocols running on the router.

Router#show ip protocol summary

Index Process Name

0     connected

1     static

2     ospf 100

*** IP Routing is NSF aware ***

12). Show Log:- Logging

Show log will display your currently configured logging settings and the buffered log messages.

core#show log

Syslog logging: enabled (0 messages dropped, 10 messages rate-limited, 2937 flus

hes, 0 overruns)

Console logging: level debugging, 66054 messages logged

Monitor logging: level debugging, 81 messages logged

Buffer logging: level debugging, 61345 messages logged

Exception Logging: size (4096 bytes)

Count and timestamp logging messages: disabled

13). Show IP ARP:-

Output shows the IP to MAC Address resolution for all the learned IP’s at the device, with the interface from which MAC Address is learned.

In the following example, the show ip arp command lists all ARP entries by interface for this router:

core_1#show ip arp

Protocol  Address                 Age (min)  Hardware Addr        Type       Interface

Internet  10.125.10.214       20            0021.5aa8.f05a     ARPA       Vlan1

14). Show mac-address-table:-

core_1#show mac-address-table

Legend: * - primary entry

age - seconds since last seen

n/a - not available

vlan   mac address       type    learn     age              ports

------+----------------+--------+-----+----------+--------------------------

*  322  000b.fcfe.1b04    dynamic  Yes          0          Po19

*    3  0100.5e01.0103    static       Yes          -

*    5  0021.5a4f.c6b8     dynamic  Yes          0        Gi6/48

*  576  3333.0000.0001    static      Yes          -   Switch,Stby-Switch

*   99  001c.7f40.16ef     dynamic    Yes        0           Po29

15). Show mac-address-table address:-

To get the switch port where the mac address is learned, you can use the following command

core_1#show mac-address-table address 0022.640b.0bc0

Legend: * - primary entry

age - seconds since last seen

n/a - not available

vlan   mac address          type    learn       age      ports

------+----------------+--------+-----+----------+--------------------------

Supervisor:

*    3  0022.640b.0bc0   dynamic  Yes          0        Po18

Supervisor:

*    3  0022.640b.0bc0   dynamic  Yes          0        Po18

16). Show interfaces link:-

"show interface link" command will display the down time for each port.

To display how long a cable has been disconnected from an interface, use the show interfaces link command:

If the interface state is up, the command displays 0:00. If the interface state is down, the time (in hours, minutes, and seconds) is displayed.

Example

Switch# show interfaces link

Port    Name               Down Time

Gi1/1                       00:00:00

Gi1/2                       00:00:00

Gi3/1              00:00:00

Gi3/2              00:00:00

Fa4/1                       00:00:00

Fa4/2                       00:00:00

Example

Switch# show interfaces link

Port    Name               Down Time

Gi3/4                      1 minute 28 secs

Gi3/5                      1 minute 28 secs

Gi3/6                      1 minute 28 secs

Gi4/1                      1 minute 28 secs

In this example, the cable has been disconnected from the port for 1 minute and 28 seconds.

17). Show Interfaces Status:-

Juniper switches don't support "show interface status"

Cisco's command displayed some useful information. port name, Status , vlan, Duplex, speed, type etc.

core_1#show interfaces status

Port     Name                            Status           Vlan       Duplex   Speed   Type

Gi3/1   G3/1 Connection to    not connect   61            auto   auto 10/100/1000BaseT

Gi3/2   Connection for TOR   connected      3            a-full a-1000 10/100/1000BaseT

Gi3/3   Gi3/3 Connection f     connected    trunk         full   1000 10/100/1000BaseT

Gi3/4   Gi3/4 Connection f     connected    trunk         full   1000 10/100/1000BaseT

Gi3/5   Gi3/5 Connection f     connected    trunk         full   1000 10/100/1000BaseT

18). Show Interfaces Summary:-

19). TRACE ROUTE:-

Trace route simply shows all the Layer3 Hops/ Devices, which comes Between Source & Destination

Traceroute works by sending packets with gradually increasing TTL value, starting with TTL value of 1. The first router receives the packet, decrements the TTL value and drops the packet because it then has TTL value zero. The router sends an ICMP Time Exceeded message back to the source.

20.Show Spanning Tree BlockPorts