Cisco commands Soofia Saleem ep: 094963

Command: Enable

Use: Switches to the privileged level command set.

Syntax: Router>enable

Example

In the below example you switch from unprivileged mode to privileged mode.

Router>Router>enableRouter#

Command: Configure Terminal

Use: To enter global configuration mode, use the configure terminal command in privileged EXEC mode.

Syntax: Router>configure terminal

Example

In this example, the user switches to global configuration mode by entering in the configure terminal command.

Router>Router>configure terminalRouter#

Command: Exit

Use: Logs you out of your session if you are in unprivileged execmode.

Syntax: Router>exit

Example

In the below example, a user switches from unprivileged mode to privileged mode.

Router>exit

Command: Hostname

Use: Sets the hostname of the router.

Syntax: Router(config)#hostname <WORD>

Example

In the below example the hostname command is used to change the router name.

R1(config)#hostname TESTTEST(config)#hostname R1R1(config)#

Command: Inteface

Use: Selects an interface on the router to enter into configuration mode.

Syntax: Router(config)#interface FastEthernet <0-6>

Example

Since there are many different interface options we have added an interface section with some of the more useful commandsfor a CCNA candidate.

This example shows how to use the interface command to enter config mode for FastEthernet 0/0

R3(config)#interface fa0/0R3(config-if)#

Command: Username

Use: Creates a new user on the router.

Syntax: Router(config)#username <WORD> password <WORD>

Example

In the following example a new user is created on the router. This user is then used when logging in via a telnet session from R2.

R1(config)#username Test password cisco

Command: Enable Secret

Use: Sets an encrypted password for enable mode on the router.

Syntax: Router(config)#enable password <WORD>

Example

In this example the enable password is set on R1.

R1(config)#enable secret ciscoR1(config)#

Next, we verify the encrypted enable password using the show run command.

R1(config)#do show run | i enableenable secret 5 $1$DFaG$gio1KhCTVIYNSZHNM2KhH0

Command: IP address

Use: This command is used to set IP addresses on an interface.

Syntax: R1(config)#ip address <IP address> <subnet mask> <secondary>

Options <IP address> IP address for the interface<subnet mask> IP address for the interface

<secondary>Sets the IP address as a secondary IP address, you can have many secondary IP addresses on an interface if required. Though some routing protocols do not function properly with secondary addresses.

Example

In this example, we set the ip address of int fa0/0 on R2.

R2(config)#int fa0/0R2(config-if)#ip add 10.1.1.2 255.255.255.0R2(config-if)#do sh ip int briefInterface IP-Address OK? Method Status ProtocolFastEthernet0/0 10.1.1.2 YES NVRAM up up

Next, to test it out, we do a quick ping to the new ip address. R2(config-if)#ip add 11.22.33.44 255.255.255.240 secondary

R2(config-if)#do ping 11.22.33.44

Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 11.22.33.44, timeout is 2 seconds:!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 msR2(config-if)#

Command: shutdown

Use: This command will administratively disable an interface. Alternatively, you can enable the interface by negating the command using no shutdown.

Syntax: Router(config-if)#shutdownORRouter(config-if)#no shutdown

Example

In the below example, we shutdown R1's Fa0/0 interface and then enable the interface again.

R1(config)#int fa0/0R1(config-if)#shutdownR1(config-if)#*Mar 1 19:17:34.339: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.1.2 (FastEthernet0/0) is down: interface down

R1(config-if)#*Mar 1 19:17:36.315: %LINK-5-CHANGED: Interface FastEthernet0/0, changed state to administratively down*Mar 1 19:17:37.315: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to down

R1(config-if)#do show ip int brInterface IP-Address OK? Method Status ProtocolFastEthernet0/0 10.1.1.1 YES NVRAM administratively down down

R1(config-if)#no shutR1(config-if)#*Mar 1 19:17:53.111: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 10.1.1.2 (FastEthernet0/0) is up: new adjacencyR1(config-if)#*Mar 1 19:17:53.411: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to up*Mar 1 19:17:54.411: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up

R1(config-if)#do show ip int brInterface IP-Address OK? Method Status ProtocolFastEthernet0/0 10.1.1.1 YES NVRAM up up

Command: Enable Password

Use: Sets a non-encrypted password for enable mode on the router.

Syntax: Router(config)#enable password <WORD>

Example

In this example the enable password is set on R1.

R1(config)#enable password ciscoR1(config)#

Next the enable password is verified using the show run command.

R1(config)#do show run | i enableenable password cisco

Command: Show IP Interface Brief

Use: This command displays a brief summary of the interfaces on a device. Its useful for quickly checking the status of the device.

Syntax: Router#show ip interface brief

Example

In the below example we use show ip interface brief to quickly see how interfaces are configured on R1.

R1#show ip interface briefInterface IP-Address OK? Method Status ProtocolFastEthernet0/0 10.1.1.1 YES NVRAM up up Serial1/0 10.4.4.1 YES manual up up Serial1/1 unassigned YES unset administratively down down Serial1/2 unassigned YES unset administratively down down Serial1/3 unassigned YES unset administratively down down Loopback0 1.1.1.1 YES NVRAM up up Loopback1 11.11.11.11 YES NVRAM up up Loopback11 1.2.2.2 YES NVRAM up up Loopback12 1.3.3.3 YES NVRAM up up Loopback22 111.111.111.111 YES NVRAM up up

Command: Service Password-Encryption

Use: Allows you to encrypt all passwords on your router so they can not be easily guessed from your running-config. This command uses a very weak encryption because the router has to be very quickly decode the passwords for its operation.It is meant to prevent someone from looking over your shoulder and seeing the password, that is all.

Syntax: R2(config)#service password-encryption

Example

Now we will encrypt the password with service password-encryption

R2(config)#service password-encryption R2(config)#do sh run | sec vty line vty 0 4password 7 060506324F41logintransport input telnet ssh

Command: Copy Running-config Startup-config

Use: This command lets you save your running configuration to the router's startup configuration (NVRAM) so it will survive a reload.

Syntax :Router#copy running-config startup-config

Example

In the below example R1's startup configuration is saved.

R1#copy run startDestination filename [startup-config]? Building configuration...

[OK]R1#

Command: Show Spanning-Tree

Use: Displays the spanning tree configuration on the switch.

Syntax: Switch#show spanning-tree

Example

In this example, the spanning tree configuration for VLAN 1 is displayed on SW3.

SW3#show spanning-tree vlan 1

VLAN0001Spanning tree enabled protocol ieeeRoot ID Priority 32769Address 0018.b973.fc80Cost 19Port 25 (FastEthernet0/23)Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)Address 0019.060c.9400Hello Time 2 sec Max Age 20 sec Forward Delay 15 secAging Time 300

Interface Role Sts Cost Prio.Nbr Type---------------- ---- --- --------- -------- --------------------------------Fa0/10 Desg FWD 19 128.12 P2p Fa0/11 Desg FWD 19 128.13 P2p Fa0/12 Desg FWD 19 128.14 P2p Fa0/13 Desg FWD 19 128.15 P2p Fa0/19 Altn BLK 19 128.21 P2p Fa0/20 Altn BLK 19 128.22 P2p Fa0/23 Root FWD 19 128.25 P2p

Interface Role Sts Cost Prio.Nbr Type---------------- ---- --- --------- -------- --------------------------------

Fa0/24 Altn BLK 19 128.26 P2p

SW3#

Command: Spanning-Tree VLAN Root Primary

Use: This command sets the switch to become root for a given VLAN. It works by lowering the priority of the switch until it becomes root. Once the switch is root, it will not prevent any other switch from becoming root.

Syntax :Swith(cconfig)#spanning-tree vlan <vlan range> root primary

Example

In the below example we will configure SW1 to become the root for VLAN 10. Currently, we see that SW1 is not root for vlan 10. Notice the priority is currently 32768

SW1(config)#do show spanning vlan 10

VLAN0010Spanning tree enabled protocol ieeeRoot ID Priority 24586Address 0019.0606.b600Cost 19Port 23 (FastEthernet0/23)Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)Address 0012.00cb.6c80Hello Time 2 sec Max Age 20 sec Forward Delay 15 secAging Time 15

Interface Role Sts Cost Prio.Nbr Type---------------- ---- --- --------- -------- --------------------------------Fa0/1 Desg FWD 19 128.1 P2p Fa0/2 Desg FWD 19 128.2 P2p Fa0/4 Desg FWD 19 128.4 P2p Fa0/5 Desg FWD 19 128.5 P2p Fa0/8 Desg FWD 19 128.8 P2p Fa0/9 Desg FWD 19 128.9 P2p Fa0/10 Desg FWD 19 128.10 P2p

Interface Role Sts Cost Prio.Nbr Type---------------- ---- --- --------- -------- --------------------------------

Fa0/19 Desg FWD 19 128.19 P2p

Fa0/20 Desg FWD 19 128.20 P2p Fa0/21 Desg FWD 19 128.21 P2p Fa0/22 Desg FWD 19 128.22 P2p Fa0/23 Root FWD 19 128.23 P2p Fa0/24 Altn BLK 19 128.24 P2p

Now we will configure SW1 to become root for Vlan 10.

SW1(config)#spanning vlan 10 root primary

We can see that SW1 is now root for Vlan 10. Notice the priority is now 24576.

SW1(config)#do show spanning vlan 10

VLAN0010Spanning tree enabled protocol ieeeRoot ID Priority 24586Address 0012.00cb.6c80This bridge is the rootHello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 24586 (priority 24576 sys-id-ext 10)Address 0012.00cb.6c80Hello Time 2 sec Max Age 20 sec Forward Delay 15 secAging Time 300

Interface Role Sts Cost Prio.Nbr Type---------------- ---- --- --------- -------- --------------------------------Fa0/1 Desg FWD 19 128.1 P2p Fa0/2 Desg FWD 19 128.2 P2p Fa0/4 Desg FWD 19 128.4 P2p Fa0/5 Desg FWD 19 128.5 P2p Fa0/8 Desg FWD 19 128.8 P2p Fa0/9 Desg FWD 19 128.9 P2p Fa0/10 Desg FWD 19 128.10 P2p Fa0/19 Desg FWD 19 128.19 P2p

Interface Role Sts Cost Prio.Nbr Type---------------- ---- --- --------- -------- --------------------------------

Fa0/20 Desg FWD 19 128.20 P2p Fa0/21 Desg FWD 19 128.21 P2p Fa0/22 Desg FWD 19 128.22 P2p Fa0/23 Desg FWD 19 128.23 P2p

Fa0/24 Desg FWD 19 128.24 P2p

Command: Spanning-Tree Portfast

Use :This command essentially disables spanning-tree on an interface and brings it immediately into the forwarding state. Only use this command on access ports

Syntax: Switch(config-if)#spanning-tree portfast

Example

Now we will configure portfast on Fa0/2.

SW1(config)#int fa0/2SW1(config-if)#spanning portfast%Warning: portfast should only be enabled on ports connected to a singlehost. Connecting hubs, concentrators, switches, bridges, etc... to thisinterface when portfast is enabled, can cause temporary bridging loops.Use with CAUTION

%Portfast has been configured on FastEthernet0/2 but will onlyhave effect when the interface is in a non-trunking mode.

Command: Show Vlan

Use: Displays the current VLAN configuration on the switch.

Syntax: Switch#show vlan

Example

Here, the VLAN configuration is displayed for SW3.

VLAN Name Status Ports---- -------------------------------- --------- -------------------------------1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4

Fa0/5, Fa0/6, Fa0/7, Fa0/8Fa0/9, Fa0/10, Fa0/11, Fa0/12Fa0/13, Fa0/14, Fa0/15, Fa0/16Fa0/17, Fa0/18, Fa0/21, Fa0/22Fa0/23, Fa0/24, Gi0/1, Gi0/210 VLAN0010 active 11 VLAN0011 active 12 VLAN0012 active 13 VLAN0013 active 14 VLAN0014 active 15 VLAN0015 active 16 VLAN0016 active 17 VLAN0017 active 18 VLAN0018 active 19 VLAN0019 active 20 VLAN0020 active 55 VLAN0055 active 99 VLAN0099 active 555 VLAN0555 active 1002 fddi-default act/unsup 1003 token-ring-default act/unsup 1004 fddinet-default act/unsup 1005 trnet-default act/unsup

Command: Show Interface-Trunk

Use: Displays the trunk information on the switch.

Syntax: Switch#show interface trunk

Example

Here's the output of show interface trunk for SW3.

SW3#show interface trunk

Port Mode Encapsulation Status Native vlanFa0/19 auto n-802.1q trunking 1Fa0/20 auto n-802.1q trunking 1Fa0/21 auto n-802.1q trunking 1Fa0/22 auto n-802.1q trunking 1

Port Vlans allowed on trunkFa0/19 1-4094Fa0/20 1-4094Fa0/21 1-4094Fa0/22 1-4094

Port Vlans allowed and active in management domainFa0/19 1,10-20,55,99,555Fa0/20 1,10-20,55,99,555Fa0/21 1,10-20,55,99,555

Fa0/22 1,10-20,55,99,555

Port Vlans in spanning tree forwarding state and not prunedFa0/19 noneFa0/20 noneFa0/21 1,10-11

Port Vlans in spanning tree forwarding state and not prunedFa0/22 none

Command: Vlan

Use: This is the legacy way to configure VLANs on a switch. While this mode is being depreciated, you will still encounter it on older switches or routers with switch modules. On newer IOS releases, VLANs are configured in configure mode.

Syntax: Switch(vlan)#vlan <number>ORSwitch(vlan)#vlan <number> name <vlan_name>

Example

2950-XL#vlan database2950-XL(vlan)#vlan 55 name MANAGEMENTVLAN 55 added:Name: MANAGEMENT

2950-XL(vlan)#exitAPPLY completed.Exiting....

Command: Show Vlan Brief

Use: Shows a basic summary of the VLAN information on the switch.

Syntax: Switch#show vlan brief

Example

Here is the show vlan brief output for SW3.

SW3#show vlan brief

VLAN Name Status Ports---- -------------------------------- --------- -------------------------------1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4

Fa0/5, Fa0/6, Fa0/7, Fa0/8Fa0/9, Fa0/10, Fa0/11, Fa0/12Fa0/13, Fa0/14, Fa0/15, Fa0/16Fa0/17, Fa0/18, Fa0/23, Fa0/24Gi0/1, Gi0/210 VLAN0010 active 11 VLAN0011 active 12 VLAN0012 active 13 VLAN0013 active 14 VLAN0014 active 15 VLAN0015 active 16 VLAN0016 active 17 VLAN0017 active 18 VLAN0018 active 19 VLAN0019 active 20 VLAN0020 active 55 VLAN0055 active 99 VLAN0099 active 555 VLAN0555 active

VLAN Name Status Ports---- -------------------------------- --------- -------------------------------1002 fddi-default act/unsup 1003 token-ring-default act/unsup 1004 fddinet-default act/unsup 1005 trnet-default act/unsup

Command: Switchport Access Vlan

Use: Sets the VLAN that the interface belongs to.

Syntax: Switch(config-if)#switchport access vlan <vlan # >

Example

In this example, port fa0/2 on SW3 is set to VLAN 10. Here is the VLAN information on SW3 before the changes. Notice that all interfaces belongto VLAN 1.

SW3#show vlan brief

VLAN Name Status Ports---- -------------------------------- --------- -------------------------------1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4, Fa0/5Fa0/6, Fa0/7, Fa0/8, Fa0/9Fa0/10, Fa0/11, Fa0/12, Fa0/13Fa0/14, Fa0/15, Fa0/16, Fa0/17Fa0/18, Fa0/19, Fa0/20, Fa0/23Fa0/24, Gi0/1, Gi0/210 VLAN0010 active

11 VLAN0011 active 12 VLAN0012 active 13 VLAN0013 active 14 VLAN0014 active 15 VLAN0015 active 16 VLAN0016 active 17 VLAN0017 active 18 VLAN0018 active 19 VLAN0019 active 20 VLAN0020 active 99 VLAN0099 active 555 VLAN0555 active 1002 fddi-default act/unsup

Next, int fa0/2 is configured for VLAN 10.

SW3#conf tEnter configuration commands, one per line. End with CNTL/Z.SW3(config)#int fa0/2SW3(config-if)#switchport access vlan 10

Finally, the VLAN information for SW3 is displayed with fa0/2 assigned to VLAN 10.

SW3(config-if)#do show vlan brief

VLAN Name Status Ports---- -------------------------------- --------- -------------------------------1 default active Fa0/1, Fa0/3, Fa0/4, Fa0/5Fa0/6, Fa0/7, Fa0/8, Fa0/9Fa0/10, Fa0/11, Fa0/12, Fa0/13Fa0/14, Fa0/15, Fa0/16, Fa0/17Fa0/18, Fa0/19, Fa0/20, Fa0/23Fa0/24, Gi0/1, Gi0/210 VLAN0010 active Fa0/211 VLAN0011 active 12 VLAN0012 active 13 VLAN0013 active 14 VLAN0014 active 15 VLAN0015 active 16 VLAN0016 active 17 VLAN0017 active 18 VLAN0018 active 19 VLAN0019 active 20 VLAN0020 active 99 VLAN0099 active 555 VLAN0555 active 1002 fddi-default act/unsup

Command: VTP Mode Server

Use: VTP Mode Server allows the switch to make changes to the VLAN database as well as propagate changes to other switches. This is the default mode for VTP

Syntax: Switch(config)#vtp mode server

Example

In the below example we will confirm that the switch is a VTP server and we will add a VLAN to it.

SW1(config)#vtp mode serverDevice mode already VTP SERVER.

SW1(config)#vlan 555SW1(config-vlan)#exit

Command: VTP Mode Client

Use: VTP client mode doesn't allow you to create any VLANs. all VLANs must be learned from a server switch. This prevents the switch from accidently propogating VLANs throughout the network. Another use is to prevent an older switch from wiping out a server's VLAN database due to it having a higher revision number.

Syntax: Switch(config)#vtp mode client

Example

In the below example we will set SW1 to be a VTP client, then add a VLAN. Notice the switch rejected the command.

SW1(config)#vtp mode clientSetting device to VTP CLIENT mode.SW1(config)#vlan 542%VTP VLAN configuration not allowed when device is in CLIENT mode.SW1(config)#

Command: VTP Mode Transparent

Use: VTP transparent mode allows the switch to modify its VLAN databasem but will not propagate changes from a server.Additionally, VTP transparent mode allows the switch to configure extended range VLANS (1006-4094).

Syntax: Switch(config)#vtp mode transparent

Example

In the below example we will configure the switch to be in VTP transparent mode and we will add a VLAN.

SW1(config)#vtp mode transparentSetting device to VTP TRANSPARENT mode.

SW1(config)#vlan 555SW1(config-vlan)#exit