Automation and Quality of Service

A network engineer is troubleshooting QoS on a Cisco ASR 1000 router. The router has a service-policy applied on the ingress interface GigabitEthernet0/0/0. The policy uses a class-map to match traffic based on NBAR protocol discovery for 'cisco-jabber'. The goal is to mark the traffic with DSCP AF41. However, when the engineer checks the policy statistics, the class 'jabber' shows zero matches, even though the users are actively using Cisco Jabber. The NBAR protocol discovery is enabled globally and on the interface. The engineer verifies that the NBAR protocol pack is up-to-date. What is the most likely reason for the class-map not matching?

Based on the exhibit, which statement is true about the QoS policy?

Refer to the exhibit. An engineer applies two service policies to the same subinterface in the outbound direction. Which statement describes the expected behavior?

An SP uses BGP FlowSpec to mitigate DDoS attacks. They also want to rate-limit the traffic per FlowSpec rule. Which configuration is required to enable policing within a FlowSpec action?

Refer to the exhibit. An engineer checks the policy and notices that the policing is not working as expected—traffic is not being dropped even when exceeding 1 Mbps. What could be the issue?

A service provider is deploying QoS on a Cisco ASR 9000 router to support a triple-play service (voice, video, data) over an Ethernet access network. The network engineer must ensure that voice traffic (EF) is prioritized, video traffic (AF41) is treated with low loss, and data traffic (default) gets best-effort service. Additionally, the engineer must implement a hierarchical QoS policy to shape the aggregate subscriber traffic to 100 Mbps on a GigabitEthernet interface, with the following per-class bandwidth allocations: voice 10 Mbps, video 40 Mbps, and data 50 Mbps. During testing, voice packets are being dropped under congestion, and video traffic is experiencing jitter. The current QoS configuration is as follows: policy-map CHILD class VOICE priority level 1 police rate 10 mbps class VIDEO bandwidth remaining ratio 40 class DATA bandwidth remaining ratio 50 ! policy-map PARENT class class-default shape average 100 mbps service-policy CHILD ! Which action should the engineer take to resolve the issues while maintaining the design objectives?

Which TWO conditions cause a router to drop packets when a police action is configured?

Refer to the exhibit. An engineer monitors the queue depths on a core interface. Which class is experiencing the most congestion?

An engineer is using NETCONF to retrieve the operational QoS statistics from a router. The response contains XML data but does not include the queueing statistics. What is the most likely reason?

Refer to the exhibit. The policy above is applied on a PE router. The customer complains that voice quality is poor. Based on the exhibit, what is the most likely cause?

A service provider uses an MPLS-TE tunnel to carry voice and data traffic. The tunnel is experiencing packet loss during congestion. The engineer wants to ensure that voice traffic receives guaranteed bandwidth and low latency while data traffic uses remaining bandwidth. Which QoS configuration should be applied on the tunnel interface?

An SP's core router experiences excessive packet drops on a congested link. The QoS policy uses CBWFQ with 4 queues. The drops occur only in the queue for a premium business class. Which is the most likely cause?

Refer to the exhibit. An engineer pushes this XML configuration via NETCONF, but the device rejects it with an error stating 'invalid policy-map structure'. What is the problem?

Which congestion avoidance technique drops packets probabilistically before the queue becomes full?

An SP engineer configures a QoS policy on an IOS XR router to re-mark DSCP from AF11 to AF22 for traffic matching a specific ACL. The policy compiles successfully but traffic is not re-marked. What is a likely reason?

A service provider operates a large MPLS network with hundreds of PE routers. They have deployed QoS policies to ensure real-time traffic (voice and video) receives priority. The policy uses LLQ with a strict priority queue for voice (DSCP EF) and another for video (DSCP AF41). Each priority queue has a policer to prevent starvation of other classes. Recently, a customer reports that their video calls are experiencing jitter and packet loss. The engineer examines the PE router connected to this customer. The interface is GigabitEthernet0/0/1 with the policy applied in the output direction. Show commands indicate that the video priority queue is frequently dropping packets, while the voice queue has no drops. The police for the video queue is set to 10 Mbps. The customer's contract guarantees 20 Mbps for video traffic. However, the actual video traffic is averaging 15 Mbps with bursts to 18 Mbps. The engineer notes that the video class also has a bandwidth command of 10 Mbps under the priority statement. What is the most likely cause of the video packet loss?

Which TWO actions are required to implement QoS trust boundaries correctly in a service provider network?

Which THREE QoS mechanisms can be used for traffic policing?

Which TWO statements accurately describe the behavior of the QoS policy shown in the exhibit?

A large enterprise recently implemented centralized QoS policies using Cisco DNA Center. The policies are pushed via RESTCONF to the branch routers. After the deployment, the branch office reports that critical business applications (like ERP) are being delayed. The network team verifies that the QoS policy is applied correctly on the WAN interface (Serial0/0/0) with a shape of 10 Mbps. The policy-map has a class for 'critical-data' with bandwidth 5 Mbps and another class for 'transactional-data' with bandwidth 3 Mbps. The remaining traffic is in class-default with fair-queue. The branch router's CPU utilization is normal. The interface output shows that the queue for critical-data is rarely full, but packets are experiencing high latency. The engineer pings from the branch server to the central site and sees 200 ms RTT normally, but up to 500 ms during peak hours. What is the most likely cause of the high latency for critical-data?

Which TWO statements about model-driven telemetry compared to SNMP are correct? (Choose two.)

An SP router is configured with a hierarchical QoS policy (parent policy shaper, child policy with CBWFQ). When applying this policy to an interface, the router reports 'Policy map not found' error. What is the most likely cause?

An automation engineer is writing a Python script using Cisco's pyATS library to validate QoS configurations across a fleet of routers. The script runs without errors but reports that all routers are compliant even though some are not. What is the most likely issue?

An SP engineer is configuring QoS on a router and needs to drop traffic that exceeds a certain rate while allowing bursts up to a specified amount. Which QoS feature should be used?

An enterprise uses IPsec VPN to connect branch offices. They apply QoS policies on the tunnel interface but notice that original DSCP markings are not preserved after encryption. Which feature should be enabled to maintain end-to-end QoS?

A network automation engineer needs to retrieve QoS policy statistics from a Cisco IOS XE device using RESTCONF. Which YANG module should be targeted?

A customer has a 100 Mbps access link and wants to limit traffic to 95 Mbps with burst allowance up to 100 Mbps. Which QoS action should be applied on the egress interface?

In an MPLS network, which field in the MPLS label header is used to carry QoS information between LSRs?

During QoS troubleshooting, you capture traffic and see that DSCP markings are not being applied as configured. Which two common misconfigurations could cause this? (Choose two.)

While troubleshooting a customer complaint about slow data transfers, you notice that traffic from a specific site is being dropped. The QoS policy on the PE router includes a police command for the customer's traffic. The observed drop rate is exactly half of the configured police rate. What is the most probable reason?

Which THREE are common causes of QoS misconfiguration on PE routers? (Choose three.)

Drag and drop the steps to configure MPLS LDP on a Cisco router into the correct order.

A network administrator configures a class map to match VoIP traffic using 'match ip dscp ef' on a Cisco router. However, the QoS policy is not applying the expected marking to VoIP packets. What is a possible reason?

Which THREE YANG data nodes are part of the Cisco-IOS-XR-qos-ma-cfg module for defining a QoS policy-map? (Choose three.)

A service provider is automating QoS policy deployment using Cisco NSO and YANG. During validation, the engineer discovers that the pushed policy is not taking effect. Which three possible causes should be investigated? (Choose three.)

Which TWO QoS mechanisms are used to provide congestion avoidance? (Choose two.)

Match each network automation tool to its primary use.

Which THREE statements about implementing QoS in an MPLS VPN environment are correct? (Choose three.)

Which TWO are valid benefits of automating QoS policy management in a large SP network? (Choose two.)

Match each BGP attribute to its category or purpose.

An engineer is configuring QoS for voice traffic on a Cisco router. Which marking should be applied to voice packets to ensure proper end-to-end prioritization?

An engineer is troubleshooting a QoS policy on a Cisco router. The policy is intended to mark voice traffic with DSCP EF and video traffic with DSCP AF41. After applying the policy, voice traffic is correctly marked, but video traffic is marked as DSCP 0. What is the most likely cause?

A service provider is implementing QoS on an MPLS network to support voice, video, and data traffic. Which queuing mechanism provides the lowest latency for real-time traffic?

A network operator deploys a QoS policy on a route reflector to classify traffic based on BGP community values. However, the policy is not matching the intended traffic. Which is the most likely cause?

Based on the exhibit, which statement is true about the applied QoS policy?

A service provider is experiencing congestion on a core link connecting two P routers. The customer traffic is classified into three classes: voice (low latency), video (low loss), and data (best effort). The current configuration uses DSCP-based classification at the PE ingress, but many customers are remarking DSCP values to gain better service, bypassing the provider's QoS policy. The provider wants to enforce a strict trust boundary at the PE and re-mark all traffic according to a per-customer contract. Additionally, the provider must offer per-customer bandwidth guarantees, ensuring that one customer's traffic does not starve another customer's traffic on the congested core link. The solution must be scalable to hundreds of customers. What should the designer recommend?

A service provider needs to prioritize voice traffic over best-effort data in an MPLS VPN. The PE router uses a QoS policy applied to the ingress interface. Which action ensures that voice packets are marked with the correct DSCP value before entering the MPLS core?

A network engineer notices that voice traffic is being dropped during congestion. The traffic is marked with DSCP EF. After reviewing the QoS policy, it is discovered that the voice traffic is not being placed into a priority queue. Which configuration change would ensure voice traffic receives priority treatment?

An SP engineer implements LLQ for VoIP traffic on a DS3 link. The policy-map calls for a priority queue of 500 kbps. The actual VoIP traffic averages 400 kbps with bursts to 600 kbps. What is the expected behavior during bursts?

A service provider is designing a QoS policy for a multi-service MPLS VPN network that carries voice, video, and data traffic. The network uses DiffServ and MPLS EXP markings. The design must ensure that voice traffic is given priority over video and data, while video traffic should have better treatment than data but not at the expense of voice. The provider plans to use a hierarchical QoS (HQoS) policy at the PE-CE interfaces. Which configuration approach best meets these requirements?

Drag and drop the steps to configure a standard ACL on a Cisco router into the correct order.

A customer is using a Cisco ASR 9000 router with hierarchical QoS (HQoS) on a subscriber interface. The parent policy sets a shape rate of 10 Mbps, but the observed traffic rate is only 8 Mbps. What is a common misconfiguration that would cause this?

Refer to the exhibit. A network automation engineer uses NETCONF to retrieve the QoS policy 'POLICE-CUSTOMER'. Based on the response, what is the effect of this policy?

A service provider has deployed a new MPLS L3VPN service for a customer with multiple sites. The customer reports intermittent voice quality issues during peak hours. The provider uses a DiffServ QoS model with MPLS EXP markings. The PE routers apply the following policy on the customer-facing interfaces: policy-map CUSTOMER-OUT class VOICE priority percent 10 set mpls experimental topmost 5 class VIDEO bandwidth remaining percent 30 set mpls experimental topmost 4 class DATA bandwidth remaining percent 70 set mpls experimental topmost 0 The core network has a simple policy that maps EXP 5 to PQ, EXP 4 to a low-latency queue, and EXP 0 to best effort. The provider monitors the network and finds that the PE-CE interfaces are not congested (average utilization is 40%), but the voice packets are experiencing jitter. The customer's voice traffic is about 5% of the link capacity. Which action is most likely to reduce the jitter?

A network administrator needs to automate the deployment of a new QoS policy on dozens of provider edge routers. Which Cisco tool is best suited for this purpose?

A network engineer is implementing QoS on a Cisco ASR 1000 for a customer with multiple service classes. The customer requires that mission-critical data not be starved when voice traffic bursts. Which two actions should the engineer take? (Choose two.)

An SP uses model-driven telemetry to monitor queue depths on core interfaces. They observe periodic spikes in the queue depth for EF traffic, causing increased latency. Which automation technique could dynamically adjust the QoS policy to mitigate the spikes?

An engineer is configuring MPLS VPN and needs to ensure that customer traffic is automatically marked with a specific QoS policy based on the VPN. Which method should be used to propagate QoS markings across the MPLS network?

During a maintenance window, an automation script pushed a QoS policy that inadvertently changed the marking for all inbound traffic on a core interface. The change was rolled back, but performance reports show that some traffic is still being marked incorrectly. What is the most logical explanation?

A service provider uses a centralized automation system to manage QoS policies via NETCONF and YANG. When attempting to push a new policy-map, the device returns an error indicating that the policy-map type is not supported in the specified location. What is the most likely cause?