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New Member

VOIP MPLS network only 40-50% utilized

We are in the process of upgrading our bandwidth at our branch locations into 3 Mbps MPLS networ and we only run Citrix traffic and IP Voice (Interoffice calls) from our Branch locations into our HQ.

We expect Bandwith utilization to typically max out at 1.6 MBPS. Do you think we need to configure QoS for the voice traffic since the circuit will only be 40-50 percent utilized? My thinking was why should I configure QoS if the bandwidth is only at 40 - 50 percent. The voice traffic should have enough bandwidth to communicate over the wire.

Is my thinking correct or should I configure QoS across this MPLS network? If I should confiure QoS what type do you recommend.

Any responses are greatly appreciated

Cisco Employee

Re: VOIP MPLS network only 40-50% utilized


I would configure QoS, because there are not only sunny days in life ...

What if you catch Nimda version 7.2beta, i.e. the newest worm out there trying to blast any valid IP in your network? I would not want to explain to my CEO why we lost telephony as well ...

So on a more technical level: QoS is needed to do resource management. As such you are right in that QoS is not needed if you have enough resources. Yet, who can guarantee this in an IP network at any point in time? I would put it QoS just as an insurance though it would not be needed during normal operation.

Saying this I might add that this is the appropriate usage anyhow, as QoS will not solve issues arising from constant lack of bandwidth. Queueing is meant to handle exceptions. There is always the possibility of the unforseen.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: VOIP MPLS network only 40-50% utilized

Wouldn't QoS helped even if its half utilized since by default is fifo and voice will be processed based on whenever it was received and cause delay.

If QoS is configured wouldn't voice be serviced first no matter what?

Cisco Employee

Re: VOIP MPLS network only 40-50% utilized

Hi Sergio,

If a link is not overloaded then forwarding will be done with line speed - there is no better treatment possible. Queueing is only invoked, if an overload condition exists. So no additional delay in case no overload condition exists, independently of traffic type.

One more remark: one should be extremely careful about interface utilization statements. If you get 50% utilization on a 30 second load interval (show interface), it could very well be that you have peaks of f.e. one second overloading the interface. One second overload, i.e. delay and drops, could already be noticeable for voip services.

Regards, Martin