QoS trigger

[filip00011]

I know that QoS triggers when there is congestion, but my problem is that. My wan connection speed is 175 Mb/s, but Cisco 3925 has gig interfaces, so there will never be congestion.

How can I trigger QoS to start working earlier?

My config

ip access-list extended qos
    permit ip any 192.168.10.0 0.0.0.255

class-map match-any traffic
    match access-group name qos

policy-map ISP
    class traffic
      priority percent 20

interface GigabitEthernet0/0

    description WAN link

    service-policy output ISP

[M. G.]

Hierarchical QOS does exactly what you need. It allows you to shape the traffic to the sub-rate speed in order to “trigger” the QOS.

Regards, 

mg

[chrihussey]

Just curious, is you ACL correct?

If this is going to an ISP shouldn't it be 192.168.10.0 0.0.0.255 to any?

[M. G.]

what exactly are you trying to do?

[filip00011]

We have a wan link with 175Mbit of bandwidth. My goal is to make sure that subnet 192.168.10.0/24 will always be able to download data. Even if other subnets utilize the whole bandwidth.

[Joseph W. Doherty]

As M.G. noted, the normal solution is to use a (parent policy) shaper set for your available bandwidth, and, if needed/desired, a (child policy) set to treat traffic as you want.

However, when you write "download data", the above approach is for egress, not ingress. Ideally, the way you deal with ingress is managing the "other side's" egress. If this cannot be done, it's often nearly impossible to manage ingress bandwidth without a special QoS appliance, and even they can have issues with ingress.