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QoS – Throttle Bandwidth Based on the Time of Day

July 8th, 2009

Scenario: Say a device in your network performs incremental backups out to a server on the internet.  These backups consume bandwidth and ruin the quality of your VoIP calls.  You wish to throttle the bandwidth for this server traffic between 6 and 10pm (when you feel you need good phone quality).
Step 1: Create an access-list that matches my file server (, but only during the day.

Router(config)# time-range DAY (creates a new time range)
Router(config-time-range)# periodic weekdays 6:00 to 22:00 (matches weekdays from 6:00am to 10:00pm)
Router(config-time-range)# periodic weekend 6:00 to 22:00 (matches weekends from 6:00am to 10:00pm)
Router(config-time-range)# exit
Router(config)# ip access-list extended SERVER
Router(config-ext-nacl)# permit ip host any time-range DAY (matches my server during the time-range I specified above)
Router(config-ext-nacl)# exit

Step 2: Create a class-map (used for QoS) that matches the SERVER access-list we just created.

Router(config)# class-map MATCH_SERVER (MATCH_SERVER is just the name)
Router(config-class-map)# match access-group name SERVER (ties in the access-list above)
Router(config-class-map)# exit

Step 3: Create a policy-map (used for QoS) that throttles the bandwidth.

Router(config)# policy-map LIMIT_SERVER (creates the policy)
Router(config-pmap)# class MATCH_SERVER (applies policy to this class)
Router(config-pmap-c)# police 80000 (limits bandwidth to 80Kbps)
Router(config-pmap-c)# exit
Router(config-pmap)# exit

Step 4: Apply the new policy to the incoming interface (the one connected to my LAN, not the Internet).

Router(config)# interface fa0/0
Router(config-if)# service-policy input LIMIT_SERVER

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