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New Member

Is port based QoS possible on cisco switch?

Hey everyone,

I work for a small local ISP and we recently started selling VoIP phone solutions. A hand full of our customers use Adtrans or PBX boxes on site. We generally plug their internal network into one port on the modem, and their Adtran or PBX into another port on the modem. The issue that we are running into is that when the link to the internal network hogs all of the bandwidth, it doesn't allow sufficient bandwidth to the phone system. This of course causes a world of issue for the phones. We don't want to put the phone systems in the internal network because we don't want the phone traffic to be natted either. So our idea is to run a line from the modem, into a switch, and a link from the internal network into the switch, and a link from the phone system into switch. This way we can implement QoS for the phone system port on the switch to be prioritized over the internal network port. The only issue is that i'm not sure how this is best done, if even possible. So my question is this; if i have a 2960 (or another cisco switch) can i make one port prioritize its traffic over another ALWAYs and in a very strict manor? 


Thanks in advance!

Cisco Employee

Hi,Please see link below


Please see link below:l


You can configure a policy map on a physical port that specifies which traffic class to act on. Actions can include trusting the CoS, DSCP, or IP precedence values in the traffic class; setting a specific DSCP or IP precedence value in the traffic class; and specifying the traffic bandwidth limitations for each matched traffic class (policer) and the action to take when the traffic is out of profile (marking).

A policy map also has these characteristics:}





New Member

thanks for the quick response

thanks for the quick response, that being said; can i make a policy map that limits to their bandwidth speed, then set priority to DSCP maked packets of "EF" and have all traffic from the phone system port marked as EF? Does this make sense? So essentially all traffic that arrives on the phone port gets marked EF, then it gets prioritized because of the policy? 

Super Bronze

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(I believe) the 2960 supports ingress polices that allow selective marking of different kinds of traffic and allows selective policing of different kinds of traffic.

The 2960, with QoS enabled, supports four egress queues.  One (I also believe) can be defined as a priority queue.  Bandwidth ratios can be assigned between the egress queues.  Queue shaping is also supported (I also believe).

Lastly (another I believe [I know the 3650/3750s do what I described - but unsure the 2960 supports all their QoS features]), you can "shape" an egress port.  (This to create possible congestion, to be managed by QoS, when the downstream supports less than physical port bandwidth.)


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