IMPLEMENTING CISCO QUALITY OF SERVICE QOS V2.3 PDF
Cisco Systems, Inc. Course Introduction. 3. The Building Blocks of QoS. .. Implementing Cisco Quality of Service (QoS) v provides learners with and QoS at this URL: resourceone.info The Implementing Cisco Quality of Service (QOS) v course provides students with in-depth knowledge of IP QoS requirements, conceptual models using. Differentiated Module 3: Introduction to Modular QoS CLI and Auto-QoS. Module 4. The Implementing Cisco Quality of Service (QOS) course provides students with in-depth knowledge of IP QoS requirements, of IP QoS on Cisco IOS switch and router platforms. Module 3: Introduction to Modular QoS CLI and AutoQoS.
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End-to-End QoS Network Design: Quality of Service for Rich-Media & Cloud design considerations and guidelines for implementing Cisco Quality of Service. QOS - Implementing Cisco Quality of Service (). Cisco Course v | Prepares you for Cisco Exam QOS. This Authorized Cisco 5-day course gives. . 2 Implementing Cisco Quality of Service (QOS) v The PDF files and any printed .
QoS meets those requirements. Summary This topic summarizes the key points discussed in this lesson. The voice network is engineered to support the required number of calls. Network administrators and architects must be able to develop QoS systems to accommodate this new traffic. This lesson describes the basic concepts and key terminology of QoS and the three key steps involved in implementing a QoS policy. QoS achieves these goals by providing tools for managing network congestion.
The goal of QoS is to provide better and more predictable network service by providing dedicated bandwidth. Cisco IOS QoS features enable you to control and predictably service a variety of networked applications and traffic types. QoS offers intelligent network services that. A one-to-one mapping between traffic classes and QoS policies need not be made.
Some data associated with key applications will require very low delay transaction-based data used in airline reservations or online banking applications. QoS for Converged Networks This topic describes the three key steps involved in implementing a QoS policy on a network. In the example..
Nonbusiness network surfing can also be delayed or even prohibited. Step 1 Identify traffic and its requirements. Step 2 Group the traffic into classes with similar QoS requirements. Study the network to determine the type of traffic running on the network and then determine the QoS requirements for the different types of traffic. Other types of data can tolerate a great deal of delay file transfers and e-mail. Measure the traffic on the network during congested periods.
QoS Requirements This topic describes how traffic is identified on a network and describes elemental QoS requirements. Conduct CPU utilization assessment on each of their network devices during busy periods to determine where problems might be occurring. What is the impact on business if a transaction is delayed by two or three seconds? Can file transfers wait until the network is quiescent? Step 1: The next step is determining the QoS problems of users.
A typical voice call will require 17 to kbps of guaranteed priority bandwidth plus an additional bps per call for voice-control traffic. QoS Traffic Requirements: The result of delays and drops are poor. While voice packets are typically small 60 to bytes.
Voice traffic usually generates a smooth demand on bandwidth and has minimal impact on other traffic as long as the voice traffic is managed. Voice packets can tolerate no more than a ms delay one-way requirement and less than 1 percent packet loss. Because drops cannot be tolerated. Multiplying these bandwidth requirements times the maximum number of calls expected during the busiest time period will provide an indication of the overall bandwidth required for voice traffic.
QoS Requirements: The minimum bandwidth for a videoconferencing stream would require the actual bandwidth of the stream dependent upon the type of videoconferencing codec being used plus some overhead.
But videoconferencing traffic is often bursty and greedy in nature and. While data traffic can demonstrate either smooth or bursty characteristics depending upon the application. There will still remain additional classes for voice and video.. Locally defined critical applications — Transactional: Interactive traffic.
It is recommended that data traffic be classified into no more than four to five classes as described in the graphic. Even different versions of the same application may have varying network traffic characteristics. In enterprise networks. Some applications use dynamic port numbers that. Because data traffic can tolerate drops. Different applications may make very different demands on the network for example.
Almost all data applications can tolerate some delay and generally can tolerate high drop rates. Traffic Classification A typical enterprise might define five traffic classes as follows: Database access. After you have defined the applications with the most critical requirements. Because of its stringent QoS requirements. QoS Traffic Classes This topic describes how to divide traffic into traffic classes. Step 2: Cisco has developed specific QoS mechanisms such as low-latency queuing LLQ that ensure that voice always receives priority treatment over all other traffic.
Use QoS marking to mark voice packets as priority 5. Minimum bandwidth 1 Mbps. Defining QoS Policies Using the traffic classes previously defined. Use QoS marking to mark critical data packets as priority 4. Maximum bandwidth kbps. Use QoS marking to mark these data packets as priority 2.
Use QoS marking to mark less-than-besteffort scavenger data packets as priority 0. Step 3: Having a QoS policy is just as important in a converged network as a security policy.
A written and public QoS policy allows users to understand and negotiate for QoS in the network. QoS Policy Cont. Voice traffic is guaranteed less than ms delay in each direction but limited to the hours of 9: Enterprise resource planning ERP applications have a high QoS priority and must be available all the time.
Summary This topic summarizes the key points discussed in this lesson.. These requirements affect how voice. The MQC offers a highly modular way to fine-tune a network. AutoQoS offers an automated method for almost instantly incorporating consistent voice QoS in a network of routers and switches. QPM provides centralized QoS design. This lesson explores in detail the four methods for implementing and managing QoS.
AutoQoS is an intelligent macro that enables you to enter one or two simple AutoQoS commands to enable all the appropriate features for the recommended QoS setting for an application on a specific interface. Using MQC. Cisco AutoQoS represents innovative technology that simplifies the challenges of network administration by reducing QoS complexity.
This was a timeconsuming. In its initial version. This was accomplished by entering one global or interface command. There are these two versions of AutoQoS: In its initial release. AutoQoS Enterprise is only supported on routers at this time.
Depending on the platform. These ten traffic types are detected as traffic crosses the WAN interfaces. AutoQoS Enterprise. This feature deploys best-practice QoS policies for voice. It was a painstaking task involving copying one interface configuration and then pasting it into other interface configurations.
CLI took a lot of time and patience. The figure illustrates an example of the complex configuration tasks involved in using CLI. The original CLI method was nonmodular—there was no way to separate the classification of traffic from the actual definition of policy. You had do both on every interface. CLI was the only way to implement QoS in a network. The use of the MQC allows the separation of traffic classification from the definition of QoS policy.
By using MQC. This enables easier initial QoS implementation and maintenance as new traffic classes emerge and QoS policies for the network evolve. A traffic policy contains one or more traffic classes and one or more QoS features. A traffic class is used to classify traffic.
These templates are used as the basis for creating the class maps and policy maps for your network. The amount of time devoted to data collection varies from network to network. The AutoQoS Enterprise feature. During this phase. This new feature applies only to router WAN interfaces. The data collected is a representative sampling of the volume and type of voice. After the class maps and policy maps are created. QoS Implementation Methods Compared This topic describes the advantages and disadvantages of using each of the methods of implementing QoS on a network.
As a result. On most networks. AutoQoS offers the fastest way to implement QoS. When an AutoQoS configuration has been generated.
MQC offers excellent modularity and the ability to fine-tune complex networks. QPM makes it easier to create and manage end-to-end differentiated services in a network. This analysis leverages that information to configure QoS policies to differentiate traffic and define the QoS functions that are applied to each type of traffic flow.
QoS Policy Manager Suite of management functions that allow network administrators to fully leverage the Cisco intelligent IP infrastructure. As a centralized tool.
By simplifying QoS policy definition and deployment. QPM enables the baselining of profile network traffic. QPM is used to monitor and provision QoS for groups of interfaces and devices. QPM allows for analyzing of traffic throughput by application or service class. Advanced network management products. Cisco provides many standards-based MIBs for use in monitoring the status of devices on a network.
In the Reports tab for QPM. These reports can graphically illustrate the overall input traffic flow divided by traffic class. Using the information collected by this MIB.
Module Summary This topic summarizes the key points discussed in this module. QoS provides network administrators and architects with a set of techniques used to manage network resources. Converged IP networks must provide secure. References For additional information. Choose three. Understanding QoS A B C D Q6 constant small-packet flow time-sensitive packets brief outages are unacceptable bursty small packet flow How much one-way delay can a voice packet tolerate?
Understanding QoS A B C D Q5 compress data and headers drop low-priority packets early increase the bandwidth of the link incorporate advanced queuing technologies Which three of these are characteristics of converged network traffic?
Module Self-Check Use the questions here to review what you learned in this module.. Choose two.. Q8 Which three of these are advantages of using MQC? This module also discusses the different QoS features and where those features are typically implemented within a network. This module discusses the different implementation models of QoS and describes how the different building blocks of QoS integrate into each model.
Because the end result of QoS implementations is to affect application traffic traversing over a QoS-enabled network. Evolving technology introduces different approaches to providing quality service to network applications.. In response to these difficulties. Module 2 The Building Blocks of QoS Overview Quality of service QoS and its implementations in a converged network are complex and create many challenges for network administrators and architects.
Managing how these building blocks are assembled and how different QoS features are used can be a difficult task. Many QoS building blocks or features operate at different parts of a network to create an end-to-end QoS system.
IntServ expects applications to signal their requirements to the network. IP networks today can use all three models at the same time.
Implementing Cisco Quality of Service(QOS)v2.2 II.pdf - QOS...
The BestEffort model was designed for best-effort. The Integrated Services IntServ model was introduced to supplement the best-effort delivery by setting aside some bandwidth for applications that require bandwidth and delay guarantees.
The network recognizes classes that require special QoS.. Network devices recognize traffic classes and provide different levels of QoS to different traffic classes. QoS is not applied to packets. With the Best-Effort model. If it is not important when or how packets arrive. With IntServ. Applications signal to the network that they require special QoS. No QoS is applied to packets. DiffServ provides the greatest scalability and flexibility in implementing QoS in a network.
Without the implementation of QoS.
The Building Blocks of QoS If QoS policies are not implemented. With the Best-Effort model.. This behavior is still predominant on the Internet today. All network packets are treated exactly the same—an emergency voice message is treated exactly like a digital photograph attached to an e-mail. Your letter will be treated exactly the same as every other letter. When you drop a letter in standard postal mail.
Packets will arrive whenever they can. Best-Effort Model Cont. The only way to reach scalability limits is to reach bandwidth limits. It is the easiest and quickest model to deploy. Critical data is treated the same as casual e-mail. The Best-Effort model also has these drawbacks: Such guarantees require an end-to-end QoS approach with both complexity and scalability limitations. IntServ was introduced to guarantee predictable network behavior for these applications. This guarantee ensures both predictable and guaranteed service levels for mission-critical applications.
There will be no impact on traffic when guarantees are made. Because IntServ reserves bandwidth throughout a network..
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Using IntServ is like having a private courier airplane or truck dedicated to the delivery of your traffic. Bandwidth that is unused. Hard QoS is accomplished by negotiating specific QoS requirements upon establishment of a connection and by using Call Admission Controls CACs to ensure that no new traffic will violate the guarantee. This model ensures quality and delivery. Large network environments that contain heavy traffic loads will be extremely challenged to track QoS guarantees for hundreds of thousands of signaled flows.
The network fulfills its commitment by maintaining the per-flow state. The edge router performs admission control to ensure that available resources are sufficient in the network. The network commits to meeting the QoS requirements of the application as long as the traffic remains within the profile specifications.
The application is expected to send data only after it gets a confirmation from the network. If resources are available. IntServ Model Cont. Every individual communication must explicitly specify its traffic descriptor and requested resources to the network. The network performs admission control based on information from the application and available network resources. The application informs the network of its traffic profile and requests a particular kind of service that can encompass its bandwidth and delay requirements.
In the IntServ model. The IntServ standard assumes that routers along a path set and maintain the state for each individual communication. IntServ inherits the connection-oriented approach from telephony network design. The application is also expected to send data that lies within its described traffic profile. The traffic classifier tells the QoS forwarding path how to classify packets from a particular flow and what forwarding treatment to provide. Controlled-load service level allows applications to have low delay and high throughput.
Guaranteed-rate service level allows applications to reserve bandwidth to meet their requirements. RSVP is currently the only standard signaling protocol designed to guarantee network bandwidth from end to end for IP networks. Using LLQ. Using WRED. Cisco implementation also allows RSVP to be initiated within the network.. Network managers can take advantage of RSVP benefits in the network. RSVP can be deployed in existing networks with a software upgrade.
RSVP can deliver a controlled-load service. RSVP uses a mean data rate. Hosts and routers also use RSVP to maintain the router and host state to provide the requested service. The problem with this is that IntServ does not scale to large networks because of the large number of concurrent RSVP flows.
The network can then provide guarantees to these individual flows. Some applications use dynamic port numbers. IntServ Model Cont.. Throughout the package network. You can choose many levels of service with DiffServ. Although QoS mechanisms in this approach are enforced and applied on a hop-by-hop basis. In addition. E-mail is generally given Best-Effort service.
QoS characteristics bandwidth and delay. Each of the classes can then be assigned a different level of service. DiffServ works like a package delivery service. With DiffServ. QoS mechanisms are used without prior signaling. Do you want two-day air delivery? Do you want three. You request and pay for a level of service when you send your package..
The soft QoS approach is not considered an end-toend QoS strategy because end-to-end guarantees cannot be enforced. As the packets traverse a network. And nonbusiness traffic can either be given very poor service or blocked entirely.
DiffServ Model Cont. DiffServ also has these drawbacks: The network participates in this QoS scheme by either reserving or not reserving network resources for the requesting end station. The IntServ architecture provides a way to guarantee network quality levels by specifically reserving services and controlling the load of traffic on devices to provide the guaranteed service requirements.
The IntServ module uses a CAC component and a policy control component to manage requests for reservations. In other words.
The IntServ solution allows end stations to make requests upon the network. This message follows in reverse the routes that the data packets use. Path-error messages are routed hop by hop using the path state.
A reservation-request message must be delivered to the sender hosts so that the hosts can set up appropriate traffic-control parameters for the first hop. A reservation-request message is sent by each receiver host toward the senders.
The path state is used to route reservation-request messages in the reverse direction. This acknowledgment message contains a copy of the reservation confirmation. RSVP supports these messages: An RSVP path message is sent by each sender along the unicast or multicast routes provided by the routing protocol. At each hop. RSVP supports the following messages: These messages are required in order for a unidirectional reservation to be made.
An acknowledgment message is sent to the unicast address of a receiver host. Reservation-request acknowledgment messages are sent as the result of the appearance of a reservation-confirmation object in a reservationrequest message. RSVP does not send any positive acknowledgment messages. A reservation-request acknowledgment message is forwarded to the receiver hop by hop to accommodate the hop-by-hop integrity-check mechanism.
A path message is used to store the path state in each node. In this example. Information carried in error messages can include the following: RSVP teardown messages remove the path and reservation state without waiting for the cleanup timeout period.
Reservation-request error messages are routed hop by hop using the reservation state. Teardown messages can be initiated by an application in an end system sender or receiver or a router as the result of state timeout. RSVP supports the following two types of teardown messages: Path-teardown messages delete the path state which deletes the reservation state. Reservation-request teardown messages delete the reservation state.
Best effort. When deployed with DiffServ. No QoS at all. If a controlled load is preferred. Guaranteed rate services compute the delay taken from the PATH messages along the RSVP path of the flow and provide this information to the receiver during the resource reservation request. When LLQ is used. The RSVP-enabled routers try to guarantee the worst-case delay that will be incurred by the flow when traveling across the network. If RSVP is configured to prefer a guaranteed rate.
Controlled load services allow an RSVP session to flow through the network with the least possible interruption from other traffic flows. RSVP provides a CAC function for reservation request which is based on whether the router has the resources to support the reservation request and whether the host making the request has the right to request the reservation.
In the data plane. In the control plane. RSVP involves use of both the control plane and the data plane. When RSVP is configured on an interface.. The figure shows that when RSVP is configured. The type of scheduling and queuing depends on whether reservations are guaranteed rate or controlled load QoS services.
In the event of congestion. These two commands turn off resource reservation protocol. The first bulleted item shows the command for enabling RSVP on an interface. With the IntServ integrated into the DiffServ model. RSVP admits or rejects calls based on a preconfigured bandwidth amount.
RSVP involves only the control plane performing admission control. With DiffServ.. This specification can occur in different ways. The network uses the QoS specification of each packet to classify. You should classify the data as few times as possible. One of the primary principles of DiffServ is that you should mark packets as close to the edge of the network as possible.
By marking the traffic at the network edge. DiffServ can be deployed gradually in large networks. It is often a difficult and time-consuming task to determine the traffic class for a data packet. Because of this backward compatibility. Within the core of the network. The primary advantage of DiffServ is scalability. The other bits are used for delay. The first six bits of the DiffServ field. This gained widespread use and became known as the original IP Precedence.
The remaining two bits are used for explicit congestion notification. This precedence is the highest user-definable IP Precedence and is typically used for delay-sensitive traffic such as VoIP. Per-Hop Behaviors Cont. There are four standard-defined AF classes.
Each class should be treated independently and should have allocated bandwidth that is based on the QoS policy. Per-Hop Behaviors Cont.. Assured Forwarding RFC The manner must be specified. This implies the presence of a smoothing or filtering function that monitors the instantaneous congestion level and computes a smoothed congestion level.
The dropping algorithm uses this smoothed congestion level to determine when packets should be discarded.
An AF implementation must detect and respond to long-term congestion within each class by dropping packets. This requires an active queue management algorithm. An example of such an algorithm is weighted random early detection WRED. The AF specification does not define the use of a particular algorithm. The dropping algorithm must treat all packets within a single class and precedence level identically.
RFC simply prioritizes packets according to the precedence value. There is no compatibility with other bits used by the ToS field.. The last three bits of the DSCP bits 2 to 4.
A packet could be assigned one of six priorities based on the value of the IP Precedence value eight total values minus two reserved values. The PHB is defined as the probability of timely forwarding. Depending upon the mechanisms it encounters. From that point on. The moment an IP packet enters the network.
This lesson describes mechanisms for implementing QoS. The prioritization. Discards specific packets based on markings to avoid network congestion. Used to enforce a rate limit based on the metering excess traffic is either dropped.
Used to mark packets based on classification. Used to drop packets early to avoid congestion later in the network. One type of link efficiency technology is packet header compression. Used to improve bandwidth efficiency through compression. Each interface must have a queuing mechanism to prioritize transmission of packets.
Traffic conditioning mechanisms that police traffic by dropping misbehaving traffic to maintain network integrity. Another technology is link fragmentation and interleaving LFI. These mechanisms also shape traffic to control bursts by queuing traffic. Each class-oriented QoS mechanism has to support some type of classification. Packet classification can be based on many factors. Classification This topic describes the purpose of classification and identifies where classification is commonly implemented in a network.
In a QoS-enabled network. If the switch or router trusts the end device. If the switch or router chooses to accept the values. If the switch or router does not trust the interface. Classification tools include network-based application recognition NBAR.
The concept of trust is key for deploying QoS. Switches and routers are generally set to not trust end devices and must specifically be configured to trust packets coming from an interface. Marking This topic describes the purpose of marking and identifies where marking is commonly implemented in a network.
Marking, also known as coloring, involves marking each packet as a member of a network class so that devices throughout the rest of the network can quickly recognize the packet class. Marking is performed as close to the network edge as possible and is typically done using MQC.
Other fields can also be marked to aid in the identification of a packet class.
Other QoS mechanisms use these bits to determine how to treat the packets when they arrive. If the packets are marked as high-priority voice packets, the packets will generally never be dropped by congestion avoidance mechanisms and will be given immediate preference by congestion management queuing mechanisms. On the other hand, if the packets are marked as low-priority file transfer packets, they will be dropped when congestion occurs and will generally be moved to the end of the congestion management queues.
Congestion Management This topic describes congestion management and identifies where congestion management is commonly implemented in a network.
Congestion management mechanisms queuing algorithms use the marking on each packet to determine in which queue to place packets. Different queues are given different treatment by the queuing algorithm based on the class of packets in the queue.
Generally, queues with highpriority packets receive preferential treatment. Congestion management is implemented on all output interfaces in a QoS-enabled network by using queuing mechanisms to manage the outflow of traffic. Each queuing algorithm was designed to solve a specific network traffic problem and has a particular effect on network performance. The Cisco IOS software for congestion management or queuing include these queuing methods:. LLQ is currently the preferred queuing method.
Congestion Avoidance This topic describes congestion avoidance and identifies where congestion avoidance is commonly implemented in a network. Congestion-avoidance mechanisms monitor network traffic loads in an effort to anticipate and avoid congestion at common network bottlenecks.
Congestion avoidance is achieved through packet dropping. Congestion avoidance mechanisms are typically implemented on output interfaces wherever a high-speed link or set of links feeds into a lower-speed link such as, a LAN feeding into a slower WAN link.
WRED increases the probability that congestion is avoided by dropping low-priority packets rather than dropping high-priority packets. WRED is not recommended for voice queues. A network should not be designed to drop voice packets. Policing and Shaping This topic describes policing and shaping and identifies where policing and shaping are commonly implemented in a network. Policing or shaping mechanisms are often used to condition traffic before transmitting traffic to a network or receiving traffic from a network.
Policing is the ability to control bursts and conform traffic to ensure that certain types of traffic get certain types of bandwidth. Policing drops or marks packets when predefined limits are reached. Policing mechanisms can be set to first drop traffic classes that have lower QoS priority markings.
Policing mechanisms can be used at either input or output interfaces. These mechanisms are typically used to control the flow into a network device from a high-speed link by dropping excess low-priority packets.
A good example would be the use of policing by a service provider to throttle a high-speed inflow from a customer that was in excess of the service agreement. In a TCP environment, this policing would cause the sender to slow its packet transmission. Tools include class-based policing and committed access rate CAR. Shaping helps smooth out speed mismatches in the network and limits transmission rates.
Shaping mechanisms are used on output interfaces. These mechanisms are typically used to limit the flow from a high-speed link to a lower-speed link to ensure that the lower-speed link does not become overrun with traffic. Shaping could also be used to manage the flow of traffic at a point in the network where multiple flows are aggregated. Service providers use shaping to manage the flow of traffic to and from customers to ensure that the flows conform to service agreements between the customer and provider.
Cisco QoS software solutions include two traffic-shaping tools to manage traffic and congestion on the network: Link Efficiency Mechanisms This topic describes the functions of compression and identifies where compression is commonly implemented in the network. Cisco IOS QoS software offers link-efficiency mechanisms that work in conjunction with queuing and traffic shaping to manage existing bandwidth more efficiently and predictably.
Real-Time Transport Protocol RTP is a host-to-host protocol that is used for carrying converged traffic including packetized audio and video over an IP network. RTP provides end-to-end network transport functions intended for applications that transmit real-time requirements, such as audio, video, simulation data multicast, or unicast network services.
By using cRTP, as shown in the illustration, the three headers with a combined 40 bytes are compressed down to 2 or 4 bytes, depending on whether the cyclic redundancy check CRC is transmitted.
This compression can dramatically improve the performance of a link. Compression would typically be used on WAN links between sites to improve bandwidth efficiency. LFI would typically be used on WAN links between sites to ensure minimal delay for voice and video traffic.
LFI can reduce delay and jitter on slower-speed links by breaking up large datagrams and interleaving low-delay traffic packets with the resulting smaller packets. This susceptibility increases as the traffic is queued on slower links. Policing and shaping are typically employed on output interfaces to control the flow of traffic from a high-speed link to lower-speed links.
It only makes sense to use congestion management. Congestion avoidance is typically employed on an output interface wherever there is a chance that a high-speed link or aggregation of links feeds into a slower link such as a LAN feeding into a WAN. Devices farther from the edge of the network. Policing is also employed on input interfaces to control the flow into a network device from a high-speed link by dropping excess low-priority packets.
On some router and switch platforms. Marking should be performed as close to the network edge as possible—in the originating network device. An IP Phone. Marking is performed as close to the network edge as possible. Lesson 5 Understanding QoS in the Life of a Packet Overview This lesson provides information regarding the application of quality of service QoS mechanisms throughout a simple network.
The lesson follows two packets—a high-priority voice packet and a low-priority file transfer packet—as they traverse a QoS-enabled network. The service provider will recognize and act upon QoS classifications made by the enterprise customer. A QoS peering relation between the enterprise and the service provider is assumed. The second packet.
The relationship shows how QoS can be effectively honored across an enterprise and service provider boundary. IEEE RTP helps synchronize real-time transmissions such as voice by time-stamping packets so that they can be resynchronized at the receiving end..
This helps minimize jitter. This means that you should move the frame before any other frames with a lower CoS. DSCP is set to 40 on output. When the frame arrives at the Cisco Catalyst switch. The packet is immediately dispatched ahead of any nonvoice packets using low-latency queuing LLQ. LLQ is designed to provide instant dispatch of voice packets ahead of data while carefully managing the dispatch of data.
If the link to the service provider is a relatively slow link. Note FIFO represents the queuing mechanism that is being used on the output interface of the service provider router. The service provider maps the enterprise customer QoS classifications into the four defined traffic classes of the service provider.
The service provider router recognizes the packet as a high-priority voice packet and assigns the packet to the real-time EF class. WRED ensures that lower-priority packets are dropped to ensure that priority packets make their way quickly through the network. The key congestion avoidance technology. Because the voice packet is marked as EF—the service provider real-time class—WRED should have no impact on the packet.
The packet is dispatched immediately using the LLQ method that always provides absolute priority to voice packets. At the edge of the service provider network. The frame jumps ahead of any nonvoice frame and is immediately dispatched to the PQ. The RTP header is used to ensure that the packet is synchronized correctly with other packets from the same voice flow and that the voice payload is delivered. This ensures that the voice traffic generated by the IP Phone will always receive priority treatment over any traffic generated by the workstation.
The switch congestion management technology— weighted round robin WRR with an expedite queue priority queue [PQ] —dispatches the frame.
In the case of the FTP frame. If the link to the service provider is congested. The AF11 class is given a minimum guarantee of bandwidth. Upon arriving at the service provider network. While in the service provider core network. As the packet leaves the service provider network. TCP would recognize that fact and request retransmission of the packet.
If the packet had been dropped at any point along the way. The packets can be re-marked along the way. The downstream devices then apply different QoS mechanisms to the packet based on its marking.
With Best Effort. There are three basic networking models: Best Effort. To implement the QoS policy. DiffServ is the more scalable model to implement the required QoS for converged networks. The network QoS policy then enforces differentiated services based on the markings. Understanding the Differentiated Services Model A B C D Q6 high scalability many service levels guaranteed service deterministic delays advanced queuing mechanisms Services are provided to which entities in the DiffServ model?
Q1 Which of these models for implementing QoS is least scalable? Identifying QoS Mechanisms classification traffic policing traffic shaping congestion management RTP helps synchronize real-time transmissions such as voice by time-stamping packets so that they can be resynchronized at the receiving end. Cisco Systems. Because there are also many options available for providing QoS to different traffic types.
In Cisco IOS software configurations. MQC configurations are consistent for different QoS mechanisms and are therefore easier to learn. Cisco Systems has unified QoS configuration by separating the different components of a QoS policy into different configuration modules.
This module will also serve as the foundation for more advanced MQC configurations that include additional QoS features and techniques. There are some instances. For those customers. Network administrators can introduce new QoS mechanisms and reuse available classification options. The separation of classification from the QoS mechanism allows new Cisco IOS versions to introduce new QoS mechanisms and reuse all available classification options.
MQC allows the same QoS policy to be applied to multiple interfaces. MQC allows the same QoS policy to be applied to multiple interfaces.. Another important benefit of the MQC is the reusability of configuration. The MQC. Attaches a service policy configured with a policy map to an interface.
Step 1 Classify traffic as voice. Step 3 Attach the traffic policy to inbound or outbound traffic on interfaces. Step 2 Build a single policy map that defines three different traffic policies different bandwidth and delay requirements for each traffic class: Step 2 Configure traffic policy by associating the traffic class with one or more QOS features using the policy-map command.
Step 1 Configure classification by using the class-map command. Each class map contains one or more conditions that determine if the packet belongs to the class. Class Maps This topic describes how a class map is used to define a class of traffic..
Routers can be configured with a large number of class maps currently limited to At least one condition has to be met to bind the packet to the class. You can create a class map by using the class-map global configuration command. All conditions have to be met to bind a packet to the class. There are two ways of processing conditions when there is more than one condition in a class map: This is the default match strategy.
Class maps are identified by case-sensitive names. If no condition is met. The process goes through the list of conditions and returns the following: If one condition is not met. At least one match command should be used within the class-map configuration mode match none is the default. If all three of these match criteria are met. Class Map Configuration This example shows a traffic class configured with the class-map match-all command: Router config class-map match-all cisco1 Router config-cmap match protocol ip Router config-cmap match qos-group 4 Router config-cmap match access-group If a packet arrives on a router with traffic class called cisco1 configured on the interface.
A class map is identified by a case-sensitive name.. The description command is used for documenting a comment about the class map. QoS group 4. Packets are checked to determine whether they match the criteria specified in the match commands. Packets that fail to meet any of the matching criteria are classified as members of the default traffic class. The MQC does not necessarily require that you associate a single traffic class to one traffic policy.
The match not command inverts the condition specified. All other values of that particular match criterion belong to the class.. This nesting can be achieved with the use of the match class-map command. This command specifies a match criterion value that prevents packets from being classified as members of a specified traffic class.
If a packet matches the specified criteria. You can associate multiple types of traffic with a single traffic class by using the match any command. The only method of combining match-any and match-all characteristics within a single traffic class is with the match class-map command. The MQC allows multiple traffic classes nested traffic classes. The packet is first evaluated to determine whether IP protocol can be used as a match criterion. To combine match-any and match-all characteristics into a single class.
The result of traffic class class4 requires a packet to match one of these three match criteria to be considered a member of traffic class class4: IP protocol and QoS group 4. This example shows how to combine the characteristics of two traffic classes.
Using the match Command This example shows a traffic class configured with the class-map match-any command: Router config class-map match-any cisco2 Router config-cmap match protocol ip Router config-cmap match qos-group 4 Router config-cmap match access-group In traffic class called cisco2. If IP protocol is not a successful match criterion. Each matching criterion is evaluated to see if the packet matches that criterion.
When a successful match occurs. Nested Traffic Class to Combine match-any and match-all Characteristics in One Traffic Class The only method for including both match-any and match-all characteristics in a single traffic class is to use the match class-map command. If the packet matches none of the specified criteria.
The knowledge and skills that a learner must have before attending this course are as follows: Skip to navigation Press Enter. Skip to search Press Enter. Skip to course offerings Press Enter. Skip to content Press Enter. Select country.
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Online Training Modality: Onsite Training Request onsite training. The course material for the class will be provided in the form of a digital eKit. Course Content QOS v2. Who should attend The primary target audiences for the course are: Pre- and post-sales technical engineers responsible for designing, implementing, or troubleshooting networks Network architects responsible for designing multiservice networks to carry voice, video, and data traffic in enterprise or service provider environments Advanced Unified Communications Specialization Master UC Specialization Master Telepresence ATP Secondary target audiences are: Prerequisites This sections lists the skills and knowledge that learners must possess to benefit fully from the course.
Course Objectives After completing this course the student should be able to: Explain the need for QoS, describe the fundamentals of QoS policy, and identify and describe the different models that are used for ensuring QoS in a network Explain the use of MQC and AutoQoS to implement QoS on the network and describe some of the mechanisms used to monitor QoS implementations Given a converged network and a policy defining QoS on the network and describe some of the mechanisms used to monitor QoS implementations Use Cisco QoS queing mechanisms to manage network congestion Use Cisco QoS congestion avoidance mechanisms to reduce the effects of congestion on the network Use Cisco QoS traffic policing and traffic shaping mechanisms to effectively limit the rate of network traffic Given a low speed WAN link, use Cisco link efficiency mechanisms to improve the bandwidth efficiency of the link Describe the recommended best practices and methods used for end-to-end QoS deployment in the enterprise.
Classroom Training Modality: United States. United Kingdom. English Enroll.
Implementing Cisco Quality of Service (QOS)
English This course is being delivered by iTLS.Target Audience. A reservation-request acknowledgment message is forwarded to the receiver hop by hop to accommodate the hop-by-hop integrity-check mechanism. Switch show mls qos maps dscp-cos Dscp-cos map: Lab 7: It is the easiest and quickest model to deploy.
One type of link efficiency technology is packet header compression. Managing how these building blocks are assembled and how different QoS features are used can be a difficult task.
A class map is identified by a case-sensitive name..
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