Quick tips for performing common tasks with Cisco networking equipment.


Restarting or Rebooting

• 
  Restart immediately
  To restart or reboot a Cisco immediately, in enable mode:
  
  Router#reload
• 
  Restart or Reload in N Minutes
  To restart or reboot a Cisco in a certain number of minutes, in enable mode:
  
  Router#reload in 5 Extra Tip: This is useful when you are afraid that the configuration changes you are about to make might break something or lock you out of the router. You tell the router to reload in a certain number of minutes, then make your changes. If it turns out your changes are catastrophic and you can't log back into the router to fix them, the router will reload in a few minutes and go back to its previous configuration.

Cisco Routing

• 
  Add a Static Route on your Cisco routers
  For example, in configuration mode:
  
  Router(config)#ip route 192.168.1.0 255.255.255.240 192.168.1.254 1
• 
  Show route table of Cisco router
  In enable mode:
  
  Router#show ip route

Cisco ARP

• 
  Clear ARP Table of your Cisco router or switch
  To clear the ARP table, in enable mode:
  
  Router#clear arp
• 
  Show ARP table of a Cisco router or switch
  To display the ARP table of a Cisco router, in enable mode:
  
  Router#show arp

Cisco Load

• 
  Show Proccessor Load of your Cisco router or switch
  Like any computer, a Cisco router can be limited by its processing power. To show the processor utilization, in enable mode:
  
  Router#show proc cpu At the beginning of the output, look for a line like this:
  
  CPU utilization for five seconds: 37%/31%; one minute: 39%; five minutes: 40%

Cisco Memory

• 
  Show Used and Available Memory of your Cisco router or switch
  Like any computer, a Cisco router can be limited by its available memory. To show the used and available memory, in enable mode:
  
  Router#show proc mem At the beginning of the output, look for a line like this:
  
  Total: 200234528, Used: 70508188, Free: 129726340

Cisco Committed Access Rate (CAR)
An example that limits an IP to 512K, with a nice, fat burst. First create the access lists.

access-list 100 permit ip any host 192.168.100.100
access-list 100 permit ip host 192.168.100.100 any
Then apply rate limiting rules to the appropriate interface:

rate-limit input access-group 100 512000 1024000 2048000 conform-action transmit exceed-action drop
rate-limit output access-group 100 512000 1024000 2048000 conform-action transmit exceed-action drop
Extra Tip: If, in a rate-limit rule, you reference an access list that does not exist, the rule will match all traffic. Usually not good.