Monday, 10 December 2007

Simple QoS

Lots of people run networks with high speed internet connections these days and almost all of them complain that they are not getting the service they want out of the line, well basic answer is get more speed, the second answer is define what you want most.

A basic QoS (quality of service) config will give you much of that internet back, also and this is something to remember unless your router is also your switch you will need a switch that can also deliver QoS other wise it will just get stuck in the LAN traffic.

So here is a simple example for your WAN interface, this will make sure your out bound traffic to the net and normally is the out bound that is the slower speed for you, is controlled. As an example if you upstream (connection to the internet leaving your router) is 512kbs and your downstream (speed from the internet to you) is 2048kbs then is safe to say that the bottle neck will be on your upstream.

Now lets look at an example bit of code, we create a class map with a name in this case highpriority so show that these type of traffic are most important and will reserve a % of bandwidth for them

Router(config)#class-map HIGHPRIORITY
match http
match pop3
match smtp
policy-map HIGHPRIORITY_POLICY
class HIGHPRIORITY
bandwidth X



X = the total % or in kbs of the bandwidth you want to allow for your
Traffic i.e. bandwidth 70 would mean 70% of the total so if your line as 512kbs the then it would mean 358kbs was now for use by traffic matching highpriority class

All this is fine but we still need to apply this is your WAN interface so just go under the WAN interface and do:

Router(config-if)#service-policy output HIGHPRIORITY_POLICY

That’s it a simple QoS for you internet connection the match set are upgraded with each ISO version so check the router for options.

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