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Cisco 3850/3650 QoS configuration

Hi Guys,


i am handling Cisco 3850/3650 as Core switch. I have attached tpology diagram here.


i want to check how i can apply QoS on this Core switches for below requirements.


  • QoS policy on the LAN including RTvo, RTvi, D1-D3 classes
  • QoS policy matched on the WAN (need to add RTvi)
  • currently looking circa
    • 80 Mbps RTvo
    • 360 Mbps RTvi
Giuseppe Larosa
Hall of Fame Master

Hello Noovi,

the Catalyst 3850 supports modular QoS like routers

see the configuration guide below



So generally speaking you can achieve your QoS configuration.

You need to configure IP ACLs that will be used to define traffic classes

a) configure ACLs that define each traffic type

b) configure class-maps . Each of them will use a match address <ACL>  to classify traffic

c) You configure a QoS policy-map

   The policy-map invokes each class-map and applies one or more action to it like for example a policer or shaper or remarking of DSCP. In addition to user class-maps you can at the end invoke the class class-default to define what to do to traffic not matching any of the previuos classes.

d) You apply the policy-map using service-policy <QoS-policy-name> in/out in interface configuration mode.

Different policy-maps can be applied to different interfaces as needed.

note: shaping is supported only outbound, policing can be applied inbound or outbound.


Another option you can use, it is to use QoS on access layer switch and server farm switch to mark traffic with DSCP values that you will then match on the core switch.

This option is usually used in a big network environment to remove the classification task using ACLs from the core switch.

In your case marking in access layer can be possible or not depending on what models are the access switch and the server farm switch


Hope to help



Georg Pauwen
VIP Expert



based on the information you provided, I have put together the QoS policy below. I am not really sure what you mean by 'D1-D3 class', so the matches are just for voice and video. The interface names are obviously arbitrary...


class-map match-all VIDEO
match dscp 34
class-map match-all VOICE
match dscp 46
policy-map VIDEO_VOICE
class VIDEO
bandwidth 360000
class VOICE
bandwidth 80000
class class-default
interface GigabitEthernet0/0
description Link from Core to Router
service-policy output VIDEO_VOICE
interface GigabitEthernet0/1
description WAN Link 1
service-policy output VIDEO_VOICE
interface GigabitEthernet0/2
description WAN Link 2
service-policy output VIDEO_VOICE