Qos Configuration help .

Unanswered Question
Oct 27th, 2009

We need to decrease the time delay in between two hops ( in between two offices) .

Reply from bytes=32 time=207ms TTL=54

Reply from bytes=32 time=211ms TTL=54

So we are just thinking whether the QoS will help us or not

If it is possible please suggest us which feature of Qos will have to configure at the Router

Thanks and Regards ,


I have this problem too.
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lgijssel Tue, 10/27/2009 - 02:44

QoS will not decrease delays below the value provided by the link.

So, you should first determine what is the minimal delay possible.

Looking at the above, this doesn't look good but the link may be very heavy loaded with traffic. Cannot judge that on two icmp replies.



Joseph W. Doherty Tue, 10/27/2009 - 06:10

As Leo notes, there's really insufficient information to say whether QoS might help. If the latency is due to distance, it won't. If this latency is due to a congested link, where a mix of traffic flows of heavy and light bandwidth usage, QoS might help improve latency for the light bandwidth usage traffic flows.

k_sinjish Tue, 10/27/2009 - 06:19

Hi..Thanks Leo and joseph for your updates..

I hope we face this delay because of the congested link . So please suggest shall I go for any Bandwidth reservation or which feature have to be enabled for the particular traffic which affects the delay .

Regards ,


lgijssel Tue, 10/27/2009 - 06:30

The first step is to determine the minimum delay that's feasible on this link.

This delay must be well within your spec.

Then you could prioritize some traffic using low latency queueing:


Beware not to prioritize too much because that would nullify your efforts.



Joseph W. Doherty Tue, 10/27/2009 - 06:59

"I hope we face this delay because of the congested link ."

Well you need to know, not hope. What's the device's interface stats show when the ping times are as you describe? Where are the two offices (i.e. same town or half way across the world)? What kind of link is this? What type of devices are you using?

Mohamed Sobair Tue, 10/27/2009 - 08:52


using QoS congestion managment & avoidance mechanisms will improve the perfromance of the delay.



Joseph W. Doherty Tue, 10/27/2009 - 12:58

"using QoS congestion managment & avoidance mechanisms will improve the perfromance of the delay. "

How do you know with the information so far posted?

Mohamed Sobair Wed, 10/28/2009 - 11:57

Hi Joseph,

The original poster wantss to decrease the delay between two hops, the main reason for the delay because of a congested link.

minimizing the congestion by applying the appropriate QoS tools would definately decrease the delay,as he also mentioned that the main reason for the delay is congestion.

I have experienced this before and found QoS helps minimizing the delay.



operaciones_redes Thu, 10/29/2009 - 10:28


im looking for a complete example about configuring a QoS in a LAN network to optimize voice traffic, citrix, etc. with switches cisco catalyst 2960

pls can you give some suggestions in cisco web page?


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