Configuration Example

You have to accomplish the following to complete the traffic class configuration:

1. Creating a class map

2. Specifying the match criteria for classifying the packet as a member of that particular class

   (For a list of supported match types, see Traffic Class Elements.)

Router# configure
Router(config)# class-map match-any qos-1
Router(config-cmap)# match qos-group 1
Router(config-cmap)# end-class-map
Router(config-cmap)# commit

Use this command to verify the class-map configuration:

Router#show class-map qos-1
1) ClassMap: qos-1    Type: qos
    Referenced by 2 Policymaps

Also see, Running Configuration.

Also see, Verification.

Related Topics

• Traffic Class Elements

• Traffic Policy Elements

Associated Commands

• class-map

• match access-group

• match dscp

• match mpls experimental topmost

• match precedence

• match qos-group

Configuration Example

You have to accomplish the following to complete the traffic policy configuration:

1. Creating a policy map that can be attached to one or more interfaces to specify a service policy

2. Associating the traffic class with the traffic policy

3. Specifying the class-action(s) (see Traffic Policy Elements)

Router# configure
Router(config)# policy-map  test-shape-1
Router(config-pmap)# class qos-1

/* Configure class-action ('shape' in this example). 
Repeat as required, to specify other class-actions */
Router(config-pmap-c)# shape average percent 40
Router(config-pmap-c)# exit

/* Repeat class configuration as required, to specify other classes */

Router(config-pmap)# end-policy-map
Router(config)# commit

See, Running Configuration.

See, Verification.

Related Topics

• Traffic Policy Elements

• Traffic Class Elements

Associated Commands

• bandwidth

• bandwidth remaining

• class

• police

• policy-map

• priority

• queue-limit

• service-policy

• set discard-class

• set dscp

• set mpls experimental

• set precedence

• set qos-group

• shape

Configuration Example

You have to accomplish the following to attach a traffic policy to an interface:

1. Creating a traffic class and the associated rules that match packets to the class (see )

2. Creating a traffic policy that can be attached to one or more interfaces to specify a service policy (see Create a Traffic Policy )

3. Associating the traffic class with the traffic policy

4. Attaching the traffic policy to an interface, in the ingress or egress direction

Running Configuration

RP/0/RP0/CPU0:R1# show run interface TwentyFiveGigE0/0/0/26.1

interface TwentyFiveGigE0/0/0/26.1 l2transport
encapsulation dot1q 25
service-policy input cos
!

RP/0/RP0/CPU0:R1# show run policy-map cos

policy-map cos
class cos1
police rate 3 mbps 
! 
! 
class cos2
police rate 2 mbps 
! 
! 
class cos3
police rate 3 mbps 
! 
! 
class class-default
police rate 4 mbps 
! 
! 
end-policy-map
! 

RP/0/RP0/CPU0:R1#

Router# configure
Router(config)# interface HundredGigE 0/6/0/18
Router(config-int)# service-policy output test-shape-1
Router(config-int)# commit

Running Configuration

/* Class-map configuration */

class-map match-any traffic-class-1
match traffic-class 1
end-class-map
!
- - -
- - -

/* Traffic policy configuration */
policy-map test-shape-1
class traffic-class-1
shape average percent 40
!
class class-default
!
end-policy-map
!
- - -
- - -

/* Attaching traffic policy to an interface in egress direction */
interface HundredGigE0/6/0/18
service-policy output test-shape-1
! 

Verification

Router# show qos interface hundredGigE 0/6/0/18 output 

NOTE:- Configured values are displayed within parentheses Interface HundredGigE0/6/0/18 ifh 0x30001f8  -- output policy
NPU Id:                        3
Total number of classes:       2
Interface Bandwidth:           100000000 kbps
VOQ Base:                      11112
VOQ Stats Handle:              0x88430698
Accounting Type:               Layer1 (Include Layer 1 encapsulation and above)
------------------------------------------------------------------------------
Level1 Class                             =   qos-1
Egressq Queue ID                         =   11113 (LP queue)
Queue Max. BW.                           =   40329846 kbps (40 %)
Queue Min. BW.                           =   0 kbps (default)
Inverse Weight / Weight                  =   1 / (BWR not configured)
Guaranteed service rate                  =   40000000 kbps
TailDrop Threshold                       =   50069504 bytes / 10 ms (default)
WRED not configured for this class

Level1 Class                             =   class-default
Egressq Queue ID                         =   11112 (Default LP queue)
Queue Max. BW.                           =   101803495 kbps (default)
Queue Min. BW.                           =   0 kbps (default)
Inverse Weight / Weight                  =   1 / (BWR not configured)
Guaranteed service rate                  =   50000000 kbps
TailDrop Threshold                       =   62652416 bytes / 10 ms (default)
WRED not configured for this class

Related Topics

• Traffic Policy Elements

• Traffic Class Elements

Associated Commands

• service-policy

Egress packet marking

• The router supports egress packet marking. Match on discard-class on egress, if configured, can be used for a marking policy only.

• An egress policy is mandatory to create a user-defined header by stripping the initial 3 bits and copying the DSCP marking to the QoS group.

L2 ingress marking

• Ingress marking limitations: For the ingress pop operation, re-marking the customer VLAN tag (CoS, DEI) is not supported.

• Egress traffic behavior: The ingress ‘pop VLAN’ is translated to a ‘push VLAN’ for the egress traffic, and (CoS, DEI) marking is supported for newly pushed VLAN tags. If two VLAN tags are pushed to the packet header at the egress side, both inner and outer VLAN tags are marked. For example:

  
  rewrite ingress tag pop 1 symmetric
  rewrite ingress tag pop 2 symmetric
  rewrite ingress tag translate 2-to-1 dot1q/dot1ad <> symmetric

VLAN tag details

• Single tag operations: When symmetrical pop 1 action is performed, the outer tag (CoS, DEI) is retained as the original frame.

IP traffic class imposition for SRv6 encapsulation

Starting Cisco IOS XR Software Release 24.2.1, you can set the IP traffic class imposition for SRv6 encapsulation using the new set ip encapsulation class-of-service CLI.

This feature allows you to set the DSCP traffic-class marking to 6 bits using the hw-module profile segment-routing srv6 mode microsegment f3216 encapsulation traffic-class policy-map-extend command. This configuration replaces the 3-bit DSCP marking set by the hw-module profile segment-routing srv6 mode microsegment f3216 encapsulation traffic-class policy-map command to 6 bits.

Packet Marking Guidelines and Limitations

Avoid conflicting packet marking configurations: While marking a packet, ensure you don’t set the IP DSCP (using the set dscp command) and the MPLS experimental imposition values (using the set mpls experimental imposition command) for the same class map. Else, neither the DSCP remarking nor the MPLS EXP values may take effect at the ingress. This will cause, per default QoS behavior, the IP precedence values to be copied to the EXP bits on the imposed packets. Such an action could lead to unintended packets marked as high-priority by your customer being forwarded as high-priority MPLS packets in the network.

Viewing statistics and counters for egress policies: The statistics and counters for the egress marking policy cannot be viewed on the router.

QoS EXP matching for Layer 2 and Layer 3 VPN traffic:

• Cisco NCS 5700 series line cards at ingress to Cisco NCS 5500 series line cards at the egress and

• Cisco NCS 5500 series line cards at ingress to Cisco NCS 5700 series line cards at egress.

Policy map limits for egress marking:

• For QOS EXP-Egress marking applied on a Layer 3 interface on Cisco routers, there is a limit of two unique policy maps per NPU.

  You can apply these policies to as many interfaces as your system resources allow. However, if you apply more than the permitted limit of unique policies, you may encounter unexpected failure.

• For QOS egress marking (CoS, DEI) applied on a Layer 2 interface, there is a limit of 13 unique policy-maps per NPU. If you exceed this number, you may encounter unexpected failure.

• Cisco NCS series routers do not support push or translate operations for dot1ad.

Usage guidelines for SRv6 encapsulation marking:

• The set ip encapsulation class-of-service command is not allowed in egress QoS policies.

• The IP encapsulation marking (set ip encapsulation class-of-service) and the MPLS experimental imposition marking (set mpls experimental) features are mutually exclusive. Both the configurations are not allowed at the same time.

• On Cisco NCS 5500 series routers, the set ip encapsulation class-of-service command is allowed only when the policy-map-extend oprion is enabled. On Cisco NCS 5700 series routers, the command is supported in native mode without enabling the policy-map-extend .

• The policy-map-extend option enables 6-bit DSCP marking for both L2 and L3 modes at the same time. It is not feasible to enable the policy-map-extend option exclusively for L2 and L3 modes due to the shared hardware resources for L2 and L3 SRv6 traffic-class.

• To support DSCP marking in NCS 5700, the propagate option must be enabled in the SRv6 configurations.

Egress EXP Marking

Supported Packet Marking Operations

This table shows the supported packet marking operations.

Class-based Unconditional Packet Marking

The packet marking feature allows you to partition your network into multiple priority levels or classes of service, as follows:

• Use QoS unconditional packet marking to set the IP precedence or IP DSCP values for packets entering the network. Routers within your network can then use the newly marked IP precedence values to determine how the traffic should be treated.

  On ingress direction, after matching the traffic based on either the IP Precedence or DSCP value, you can set it to a particular discard-class. Weighted random early detection (WRED), a congestion avoidance technique, thereby uses discard-class values to determine the probability that a packet is dropped.

  If however, you set a discard-class of 3, the packet is dropped at ingress itself.

• Use QoS unconditional packet marking to assign MPLS packets to a QoS group. The router uses the QoS group to determine how to prioritize packets for transmission. To set the traffic class identifier on MPLS packets, use the set traffic-class command in policy map class configuration mode.

  Note	Setting the traffic class identifier does not automatically prioritize the packets for transmission. You must first configure an egress policy that uses the traffic class.

• Use QoS unconditional packet marking to assign packets to set the priority value of IEEE 802.1p/
Inter-Switch Link (ISL) packets. The router uses the CoS value to determine how to prioritize packets for transmission and can use this marking to perform Layer 2-to-Layer 3 mapping. To set the Layer 2 CoS value of an outgoing packet, use the set cos command in policy map configuration mode.

• Use QoS unconditional packet marking to mark a packet based on the drop eligible indicator value (DEI) bit on 802.1ad frames. To set the DEI value, use the set dei command to set the drop eligible indicator value (DEI) in policy map class configuration mode.

Note	Unless otherwise indicated, the class-based unconditional packet marking for Layer 3 physical interfaces applies to bundle interfaces.

Configuration Example

Router# configure
Router(config)# policy-map ingress-set-dscp-zero-policy
Router(config-pmap)# class class-default 
Router(config-pmap-c)# set dscp 0
Router(config-pmap-c)# end-policy-map
Router(config-pmap)# commit

Running Configuration

policy-map ingress-set-dscp-zero-policy
class class-default
  set dscp 0
! 
end-policy-map
!