Show Commands

Router#show ?	Lists all show commands available
Router#show interfaces	Displays statistics for all interfaces
Router#show interface serial 0	Displays statistics for a specific interface, in this case Serial 0
Router#show ip interface brief	Displays a summary of all interfaces, including status and IP address assigned
Router#show controllers serial 0	Displays statistics for interface hardware. Statistics display if the clock rate is set and if the cable is DCE, DTE, or not attached
Router#show clock	Displays time set on device
Router#show hosts	Displays local host-to-IP address cache. These are the names and addresses of hosts on the network to which you can connect
Router#show users	Displays all users connected to device
Router#show history	Displays history of commands used at this edit level
Router#show flash	Displays info about Flash memory
Router#show version	Displays info about loaded software version
Router#show arp	Displays the ARP table
Router#show protocols	Displays status of configured Layer 3 protocols
Router#show startup-config	Displays configuration saved in NVRAM
Router#show running-config	Displays configuration currently running in RAM

Configuring SSH on Cisco Router

This configuration is based on router with 3600 Software (C3640-JK9O3S-M), Version 12.2(6a) but it may applies to Cisco IOS 12.1(3)T and later.

Configure hostname to your router.
Router(config)# hostname hostname

Configure domain name
Router(config)#ip domain-name domainname

To automatically enables SSH, generate RSA key pair.
Router(config)# crypto key generate rsa

Type the size of key modulus in the range of 360 to 2048.
Typing 512 may takes few minutes.
How many bits in the modulus [512]: 768
% Generating 768 bit RSA keys ...[OK]
Router(config)#
*Mar 16 01:20:15.440: %SSH-5-ENABLED: SSH 1.5 has been enabled

You can change ssh setting if you wish.
Time-out should not exceed 120s which is the default. 
Authentication retries should not exceed 5,default is 3.

Router(config)# ip ssh {[timeout seconds] |[authentication-retries integer]}

Verifying SSH
Router# show ip ssh
SSH Enabled - version 1.5
Authentication timeout: 120 secs; Authentication retries: 5
Router# show ssh
%No SSH server connections running.

Troubleshooting VLANs

Displays the complete VLAN database
Switch#show vlan

Displays a summary of the VLAN database
Switch#show vlan brief

Displays a summary of each interface, including speed and duplex settings
Switch#show interfaces

Displays information about VLAN packets a router has received but is not capable of supporting
Switch#debug sw-vlan packets

Deleting VLAN Configuration

1900 Series Switch
1900Switch#delete vtp
or
1900Switch(config)#int fa 0/2
1900Switch(config-if)#no vlan static 2
1900Switch(config-if)#exit
1900Switch(config)#no vlan 2 name Sales
1900Switch(config)#

2900/2950 Series Switch
2900Switch#delete flash:vlan.dat
Delete filename [ ]? vlan.dat
Delete flash:vlan.dat? [confirm]
2900Switch#
or
2900Switch#config t
2900Switch(config)#int fa 0/3
2900Switch(config-if)#no switchport access vlan 3
2900Switch(config-if)#exit
2900Switch(config)#exit
2900Switch#vlan database
2900(vlan)#no vlan 3
2900(vlan)#exit

Setting Web-Based Interface for Configuration

For 1900 and 2900/2950 Series Switches

Turns on HTTP service
Switch(config)#ip http server

Set Port for http
Switch(config)#ip http port 80

VLAN Configurations for 2900/2950 Series Switch

2900 Series Switch

Enters VLAN database mode
2900#vlan database

Creates VLAN 2 and names it Sales
2900(vlan)#vlan 2 name Sales

Creates VLAN 3 and names it HR
2900(vlan)#vlan 3 name HR

2900(vlan)#exit

2950 Series Switch

2950Switch#config t

Creates VLAN 10 and enters VLAN config mode for further definitions
2950Switch(config)#vlan 10

Assigns a name to a VLAN
2950(config-vlan)#name Sales
2950(config-vlan)#exit

Creates VLAN 20 and enters VLAN config mode for further definitions
2950Switch(config)#vlan 20

Assigns a name to a VLAN
2950(config-vlan)#name HR
2950(config-vlan)#exit

Assigning ports to VLAN 2900/2950
2900Switch#config t
2900Switch(config)#int fa0/2
2900Switch(config-if)#switchport mode access
2900Switch(config-if)#switchport access vlan 2
2900Switch(config-if)#int fa0/3
2900Switch(config-if)#switchport mode access
2900Switch(config-if)#switchport access vlan 3
2900Switch(config-if)#exit

VLAN Configurations for 1900 Series Switch

Creating Static VLAN

1900#config t
Make VLAN 2 and name it Sales
1900(config)#vlan 2 name Sales

Make VLAN 2 and name it HR
1900(config)#vlan 3 name HR

Assigning Ports to VLAN
1900#config t
1900(config)#int Fa0/2
1900(config-if)#vlan static 2
1900(config-if)#int fa0/3
1900(config-if)#vlan static 3
1900(config-if)#exit