The Cisco PE router must be configured to enforce a Quality-of-Service (QoS) policy to provide preferred treatment for mission-critical applications.

Different applications have unique requirements and toleration levels for delay, jitter, bandwidth, packet loss, and availability. To manage the multitude of applications and services, a network requires a QoS framework to differentiate traffic and provide a method to manage network congestion. The Differentiated Services Model (DiffServ) is based on per-hop behavior by categorizing traffic into different classes and enabling each node to enforce a forwarding treatment to each packet as dictated by a policy.

Packet markings such as IP Precedence and its successor, Differentiated Services Code Points (DSCP), were defined along with specific per-hop behaviors for key traffic types to enable a scalable QoS solution. DiffServ QoS categorizes network traffic, prioritizes it according to its relative importance, and provides priority treatment based on the classification. It is imperative that end-to-end QoS is implemented within the IP core network to provide preferred treatment for mission-critical applications.

Review the router configuration and verify that a QoS policy has been configured to provide preferred treatment for mission-critical applications.

Step 1: Verify that the class-maps are configured to match on DSCP values as shown in the configuration example below.

class-map match-all C2_VOICE match ip dscp af47 class-map match-all VOICE match ip dscp ef class-map match-all VIDEO match ip dscp af41 class-map match-all CONTROL_PLANE match ip dscp cs6 class-map match-all PREFERRED_DATA match ip dscp af33

Step 2: Verify that the policy map reserves the bandwidth for each traffic type as shown in the following example:

policy-map QOS_POLICY class C2_VOICE priority percent 10 class VOICE priority percent 15 class VIDEO bandwidth percent 25 class CONTROL_PLANE priority percent 10 class PREFERRED_DATA bandwidth percent 25 class class-default bandwidth percent 15

Step 3: Verify that an output service policy is bound to all interfaces as shown in the configuration example below.

interface GigabitEthernet1/1 ip address 10.1.15.1 255.255.255.252 service-policy output QOS_POLICY ! interface GigabitEthernet1/2 ip address 10.1.15.4 255.255.255.252 service-policy output QOS_POLICY

Note: Enclaves must mark or re-mark their traffic to be consistent with the DODIN backbone admission criteria to gain the appropriate level of service. A general DiffServ principle is to mark or trust traffic as close to the source as administratively and technically possible. However, certain traffic types might need to be re-marked before handoff to the DODIN backbone to gain admission to the correct class. If such re-marking is required, it is recommended that the re-marking be performed at the CE egress edge.

If the router is not configured to enforce a QoS policy in accordance with the QoS DODIN Technical Profile, this is a finding.

Configure to enforce a QoS policy to provide preferred treatment for mission-critical applications.

Step 1: Configure class-maps to match on DSCP values as shown in the configuration example below.

R5(config-cmap)#class-map match-all C2_VOICE R5(config-cmap)#match ip dscp 47 R5(config-cmap)#class-map match-all VOICE R5(config-cmap)#match ip dscp ef R5(config-cmap)#class-map match-all VIDEO R5(config-cmap)#match ip dscp af41 R5(config-cmap)#class-map match-all CONTROL_PLANE R5(config-cmap)#match ip dscp cs6 R5(config)#class-map match-all PREFERRED_DATA R5(config-cmap)#match ip dscp af33 R5(config-cmap)#exit

Step 2: Configure a policy map to be applied to the core-layer-facing interface that reserves the bandwidth for each traffic type as shown in the example below.

R5(config)#policy-map QOS_POLICY R5(config-pmap-c)#class C2_VOICE R5(config-pmap-c)#priority percent 10 R5(config-pmap-c)#class VOICE R5(config-pmap-c)#priority percent 15 R5(config-pmap-c)#class VIDEO R5(config-pmap-c)#bandwidth percent 25 R5(config-pmap)#class CONTROL_PLANE R5(config-pmap-c)#priority percent 10 R5(config-pmap-c)#class PREFERRED_DATA R5(config-pmap-c)#bandwidth percent 25 R5(config-pmap-c)#class class-default R5(config-pmap-c)#bandwidth percent 15 R5(config-pmap-c)#exit R5(config-pmap)#exit

Step 3: Apply the output service policy to the core-layer-facing interface as shown in the configuration example below.

R5(config)#int g1/1 R5(config-if)#service-policy output QOS_POLICY R5(config-if)#exit R5(config)#int g1/2 R5(config-if)#service-policy output QOS_POLICY R5(config-if)#end