A queue is reserved for each class and traffic belonging to a class is directed to that class queue

CBWFQ extends the standard WFQ functionality to provide support for user-defined traffic classes. With CBWFQ, you define the traffic classes based on match criteria, including protocols, ACLs, and input interfaces. Packets satisfying the match criteria for a class constitute the traffic for that class. A queue is reserved for each class, and traffic belonging to a class is directed to that class queue. After a class has been defined according to its match criteria, you can assign...

An SNMP structure that describes the particular device being monitored

An MIB is a Simple Network Management Protocol (SNMP) structure that describes the particular device being monitored. Cisco provides many standards-based MIBs for use in monitoring the status of devices on a network. Advanced network management products, such as CiscoWorks QPM, use these MIBs to generate statistics about the performance of the network. Specialized QoS MIBs enable QPM to graphically display key QoS information to aid in the management of QoS policies on the network. Note See the...

Applying Link Efficiency Mechanisms

Header compression and LFI are typically configured at the WAN edge for WAN links below T1 or E1 speeds to optimize the use of the WAN link and to prevent long serialization delay. Layer 2 payload compression is less commonly deployed on WAN links, especially without the use of hardware-assisted payload compression.

Applying QoS to Input and Output Interfaces

(As close to the source as possible) (Coming from a higher-speed link or aggregation) In a QoS-enabled network, classification is performed on every input interface. Marking should be performed as close to the network edge as possible in the originating network device, if possible. Devices farther from the edge of the network, such as routers and switches, can be configured to trust or untrust the markings made by devices on the edge of the network. An IP Phone, for example, will not trust the...

Bgppolicy source destination ipprecmap ipqosmap

The IP precedence bit or QoS group ID from the source address entry in the route table The IP precedence bit or QoS group ID from the destination address entry in the route table QoS policy based on the IP precedence The QoS policy based on the QoS group ID Note If you specify both source and destination on the interface, the software looks up the source address in the routing table and classifies the packet based on the source address first then the software looks up the destination address in...

Catalyst 2950 and 3550 Switches

During QoS processing, the switch represents the priority of all traffic (including non-IP traffic) with an internal DSCP value. During classification, QoS uses configurable mapping tables to derive the internal DSCP (a six-bit value) from received CoS value. Before the traffic reaches the scheduling stage, QoS uses the configurable DSCP-to-CoS map to derive a CoS value from the internal DSCP value. The show policy-map interface command displays all service policies applied to the interface. In...

CBWFQ and LLQ

Basic methods are combined to create more versatile queuing mechanisms. Basic methods are combined to create more versatile queuing mechanisms. Neither the basic queuing methods nor the more advanced WFQ completely solve quality of service (QoS) problems resulting from converged network traffic. These problems remain If only priority queuing (PQ) is used for a voice-enabled network, voice will get the priority needed, but data traffic will likely starve out at some point. If only custom queuing...

CDP must be enabled for AutoQoS to function properly

To configure the QoS settings and the trusted boundary feature on the Cisco IP Phone, CDP version 2 or later must be enabled on the port. If the trusted boundary feature is enabled, a syslog warning message displays if CDP is not enabled or if CDP is running version 1. CDP needs to be enabled only for the ciscoipphone QoS configuration CDP does not affect the other components of the automatic QoS features. When the ciscoipphone keyword with the port-specific automatic QoS feature is used, a...

EtoPE QoS for Frame Relay Access CE Outbound

Match ip access-group 101 class-map match-all BUSINESS match ip acces s-group 102 policy-map OUT-POLICY class PREMIUM priority percent 25 set ip dscp ef class BUISNESS bandwidth remaining percent 75 set ip dscp af31 random-detect dscp-based class class-default bandwidth remaining percent 25 set ip dscp 0 random-detect dscp-based The figure shows the QoS configurations on the managed CE router outbound interface to implement the required QoS policy required for each of the three service provider...

EtoPE QoS for Frame Relay Access PE Inbound

The figure shows the QoS configurations on the ingress PE router inbound interface to implement the required QoS policy that is required for each of the three service provider traffic classes. In this case, a traffic policy called IN-POLICY is configured to provide the required class-based policing. For the premium class, the rate limit is set to 25 percent of the link bandwidth. All exceeding premium-class traffic is dropped. For the business class, the rate limit is set to 38 percent of the...

Cisco IOS Traffic Policing Mechanisms

Conform, exceed, violate Drop, set, transmit Single or dual token bucket Single or dual rate policing Multi actions The figure lists the characteristics of the class-based traffic-policing mechanism that is available in Cisco IOS software. Class-based policing is also available on some Cisco Catalyst switches. Class-based policing supports a single or dual token bucket. Class-based policing also supports single-rate or dual-rate metering and multiaction policing. Multiaction policing allows...

Cisco IOS Traffic Shaping Mechanisms

Subinterface or group or class-based The figure lists some of the different traffic-shaping mechanisms available in Cisco IOS software the newer class-based traffic shaping, Distributed Traffic Shaping (DTS), and FRTS. Class-based traffic shaping uses MQC to allow traffic to be shaped per traffic class as defined by the class map. You can use class-based traffic shaping in combination with class-based weighted fair queuing (CBWFQ), in which the shaped rate is used to define an upper rate limit...

Classbased configuration of WRED is identical to standalone WRED

Congestion avoidance techniques monitor the network interface load in an effort to anticipate and avoid congestion at common network bottlenecks. Congestion avoidance is achieved through intelligent packet dropping techniques. Traditionally, Cisco IOS software used standalone RED and WRED mechanisms to avoid congestion on an interface. Those mechanisms can perform a differentiated drop based on the IP precedence or DSCP value. The class-based weighted fair queuing (CBWFQ) system supports the...

Classbased policing is configured using the MQC method

The class-based policing feature performs these functions Limits the input or output transmission rate of a class of traffic based on user-defined criteria Marks packets by setting different Layer 2 or Layer 3 markers, or both You can implement class-based policing using a single or double token bucket method as the metering mechanism. When the violate action option is not specified in the police MQC command, the single token bucket algorithm is engaged when the violate action option is...

Class Based TCP Header Compression Example Cont

Overhead 46 (46 + 5) Overhead 90 Delay (46 + 5) 64 kbps Delay 6 ms Overhead 10 (10+ 5) Overhead 67 Delay (10 + 5) 64kbps * 8 Delay 2 ms The figure shows the packet size before and after TCP header compression. After TCP header compression, the IP and TCP headers are reduced to 4 bytes, resulting in 10 bytes of overall headers. The overhead is reduced from 90 percent to 67 percent when small packets are used. Because of the packet size reduction, the serialization delay decreases from 6 ms to 2...

Classification and Marking at the Data Link Layer Cisco ISL Class of Service

ISL encapsulation adds 30 bytes to Ethernet frame ISL header contains VLAN field VLAN field consists of VLAN ID and CoS Supports up to 8 classes of service Focuses on support for QoS over ISL trunks Preserved through the LAN, not end to end ISL encapsulation adds 30 bytes to Ethernet frame ISL header contains VLAN field VLAN field consists of VLAN ID and CoS Supports up to 8 classes of service Focuses on support for QoS over ISL trunks Preserved through the LAN, not end to end 006 Cisco...

Classification and Marking on Catalyst 2950 Switches

Port can be configured to trust CoS, DSCP, or Cisco IP Phone (default untrusted) Has default CoS-to-DSCP and DSCP-to-CoS maps Can use class-based marking to set DSCP No VLAN-based classification Limited ACLs no port range IP precedence is encoded into the three high-order bits of the type of service (ToS) field in the IP header. It supports eight classes. two of which (IP precedence 6 and 7) are reserved for control-plane traffic and should not be used for user-defined classes. IP Precedence 0...

Classification and Marking on Catalyst Switches

IP Precedence (Module-Dependent) Extend Trust to IP Phone Classification can be performed only on the Catalyst 6500 when QoS has been globally enabled. By default, QoS is globally disabled and classification does not occur. With a policy feature card (PFC), QoS can classify traffic that is addressed to a specified MAC address, or VLAN pairs to be marked with a configured CoS value. Classification can also be performed against Layer 3 and Layer 4 values. Marking may be by Layer 2 CoS or Layer 3...

Comparing Methods for Implementing QoS

Cisco recommends the use of MQC and AutoQoS VoIP when deploying voice over the LAN, and AutoQoS Enterprise on router WAN interfaces. While MQC is much easier to use than CLI, AutoQoS VoIP and AutoQoS Enterprise can simplify the configuration of QoS. As a result, you can accomplish the fastest implementation with AutoQoS. MQC offers excellent modularity and the ability to fine-tune complex networks. AutoQoS offers the fastest way to implement QoS, but has limited fine-tuning capabilities. When...

Configuring and Monitoring Policy Maps

This topic describes the Cisco IOS MQC commands required to configure and monitor a policy map. You can configure service policies by using the policy-map command. Use up to 256 classes within one policy map by using the class command with the name of a preconfigured class map. You can also use a nonexistent class within the policy-map configuration mode if the match condition is specified after the name of the class. The running configuration will reflect such a configuration by using the...

Configuring CBWRED

This topic describes the Cisco IOS commands that are required to configure CB-WRED. To configure CB-WRED (WRED at the class level with CBWFQ), configure the DSCP-based and precedent-based arguments within MQC. Specific CB-WRED configuration arguments are applied within a policy map. You can then apply the policy map configuration wherever policy maps are attached (for example, at the interface level, the per-virtual circuit VC level, or the shaper level). Enables IP precedence-based WRED in the...

Configuring Classification Using DSCP

Match ip dscp ip-dscp-value ip-dscp-value Select up to eight DSCP values or names. All packets marked with one of the selected DSCP values are matched by this class map. IP packets can also be classified based on the IP DSCP field. A QoS design can be based on IP precedence marking or DSCP marking. DSCP standards make IP precedence marking obsolete but include backward compatibility with IP precedence by using the Class Selector (CS) values (which are 6-bit equivalents to their IP precedence...

Configuring CoSto Queue Mappings for PQ on Catalyst 2950 Switches

This topic describes the commands required to configure CoS-to-queue mappings for PQ on the Cisco Catalyst 2950 switch. To configure CoS-to-queue mappings for PQ on the Catalyst 2950 switch, specify the queue ID of the CoS priority queue. Ranges are 1 to 4 where 1 is the lowest CoS priority queue. Then, specify the CoS values that are mapped to the queue ID. The queue ID of the CoS priority queue. Ranges are 1 to 4 where 1 is the lowest CoS priority queue. The CoS values that are mapped to the...

Configuring FRF12 Frame Relay Fragmentation

This topic describes the Cisco IOS commands that are required to configure FRF. 12. This topic describes the Cisco IOS commands that are required to configure FRF. 12. FRF. 12 fragmentation is configured within the Frame Relay map class. The frame-relay fragment command sets the maximum fragment size in bytes. On an interface, the frame-relay class command applies the map class to the interface, subinterface, or a DLCI. FRF. 12 requires FRTS to be enabled. The figure shows a configuration...

Configuring NBAR for Stateful Protocols

This topic describes the Cisco IOS commands that are required to configure NBAR to recognize TCP and UDP stateful protocols. NBAR has enhanced classification capabilities for HTTP. It can classify packets belonging to HTTP flows based on the following The URL portion after the host name, which appears in the GET request of the HTTP session The host name specified in the GET request The MIME type specifying the type of object in the HTTP response Note The match protocol command has been...

Converged traffic characteristics

Constant small-packet voice flow competes with bursty data flow Critical traffic must get priority Voice and video are time-sensitive Brief outages not acceptable Order Entry, Finance, Manufacturing, HR, Training, Other Order Entry, Finance, Manufacturing, HR, Training, Other The figure illustrates a converged network in which voice, video, and data traffic use the same network facilities. Merging these different traffic streams with dramatically differing requirements can lead to a number of...

CoStoDSCP Default Mapping

To define the ingress CoS-to-DSCP mapping for trusted interfaces, use the mls qos map cos-dscp command. The CoS-to-DSCP map is used to map the CoS of packets arriving on trusted interfaces (or flows) to a DSCP where the trust type is trust-cos. This map is a table of eight CoS values (0 through 7) and their corresponding DSCP values. Use the no form of this command to remove a prior entry.

Default CoS assignment can be altered during configuration

The default QoS settings for the Catalyst 2950 and 3550 switches are as follows The default port CoS value is 0. The CoS value of 0 is assigned to all incoming packets. The default port trust state is untrusted. If a port is connected to an IP Phone, you should change the default port configuration to trust the CoS setting from the IP Phone using the mls qos trust command. No policy maps are configured. No policers are configured. The default CoS assignments to priority queues are as follows...

Deploying Endto End QoS Cont

E2E QoS Enterprise QoS + Service Provider QoS E2E QoS Enterprise QoS + Service Provider QoS Classification Trust on IP Multiple Queues on Switch Ports Classification Trust on IP Multiple Queues on Switch Ports Multiple Queues on Switch Ports WRED within Data Queue for Congestion Avoidance Link Fragmentation and Interleaving To provide end-to-end QoS, both the enterprise and the service provider must implement the proper QoS mechanisms to ensure the proper per-hop behavior (PHB) for each traffic...

Differentiates probability of timely forwarding xyz000 abc000 if xyz abc

- If a packet has DSCP 011000, it has a greater probability of timely forwarding than a packet with DSCP 001000. The meaning of the eight bits in the DiffServ field of the IP packet has changed over time to meet the expanding requirements of IP networks. Originally, the field was referred to as the ToS field and the first three bits of the field (bits 7 to 5) defined a packet IP Precedence value. A packet could be assigned one of six priorities based on the value of the IP Precedence value...

Displays information about individual multilink fragments and interleaving events

The debug ppp multilink fragments command is a valuable troubleshooting tool when monitoring MLP LFI operations. This command outputs the result of every fragmentation operation, indicating whether the packets are fragmented into correct-sized fragments. Caution This command should be used with extreme caution in a production environment, because of the amount of output that is created.

Displays interface delays including the activated queuing mechanism with the summary information

Router> show interface serial 1 0 Hardware is M4T Internet address is 20.0.0.1 8 MTU 1500 bytes, BW 19 Kbit, DLY 20000 usee, rely 255 255, load 147 255 Encapsulation HDLC, ere 16, loopback not set Keepalive set (10 sec) Last input 00 00 00, output 00 00 00, output hang never Last clearing of show interface counters never Input queue 0 75 0 (size max drops) Total output drops 0 Queueing strategy weighted fair Output queue 0 1000 64 0 (size max total threshold drops) Conversations 0 4 256...

Displays parameters and statistics of CBWFQ

Router> show policy-map interface FastEthernet0 0 Class-map Classl (match-any) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match any Bandwidth remaining 20 ( ) Max Threshold 64 (packets) (pkts matched bytes matched) 0 0 (depth total drops no-buffer drops) 0 0 0 Class-map class-default (match-any) 42 packets, 4439 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match any The show policy-map interface command displays all service policies applied to the interface. The...

Displays the configuration of all classes configured for all service policies on the specified interface

Router show policy-map interface Serial4 1 Serial4 1 Service-policy output policy_ecn Class-map prec1 (match-all) 1000 packets, 125000 bytes 30 second offered rate 14000 bps, drop rate 5000 bps (pkts matched bytes matched) 989 123625 (depth total drops no-buffer drops) 0 455 0 exponential weight 9 explicit congestion notification The show policy-map interface command displays the configuration of all classes configured for all service policies on the specified interface. The counters displayed...

Displays the configuration of all classes for a specified service policy map or all classes for all existing policy maps

The show policy-map command can be used to verify the configuration of a policy map. The show policy-map command can be used to verify the configuration of a policy map. The show policy-map command also displays live information if the interface keyword is used. The sample output shows the parameters and statistics of the policy map that is attached to outbound traffic on interface FastEthernet0 0. This topic describes how a service policy is assigned to an interface. This topic describes how a...

Does not display any user changes to the configuration that might be in effect

Initial configuration applied by AutoQoS mls qos map cos-dscp 0 8 16 26 32 46 48 56 To display the initial AutoQoS configuration, use the show auto qos interface interface-id privileged EXEC command. To display any user changes to that configuration, use the show running-config privileged EXEC command. You can compare the show auto qos and the show running-config command output to identify the user-defined QoS settings. show mls qos interface interface-id vlan vlan-id buffers policers queueing...

DSCP 4863 to queue

At the distribution switch, configure the trust boundary to trust the DSCP or CoS marking from the core and access layer switches. For Layer 2-to-Layer 3 and Layer 3-to-Layer 2 QoS mappings, the Catalyst 4500 has default CoS-to-DSCP and DSCP-to-CoS mappings. However, you can manually configure these default mappings to override the default mappings. The Catalyst 4500 has these CoS-to-DSCP and DSCP-to-CoS mappings You can also implement class-based policing to rate-limit certain traffic classes....

Each segment has 46 bytes of overhead Ppp Ip Udp and RTP headers

The example shows the benefits of RTP header compression on slow links. A 64-kbps link is used to transport VoIP using PPP as the Layer 2 framing protocol. For the case study application (voice, using the G.729 audio compression codec), the payload size is 20 bytes. Because PPP has 6 bytes of frame header, the total header overhead is 6 + 20 + 8 + 12 46 bytes, including the PPP, IP, UDP, and RTP headers. Class-Based RTP Header Compression Example (Cont.) Overhead 46 (46 + 20) 70 Overhead 10 (10...

Enterprise to Service Provider QoS Class Mapping Example

The figure illustrates how the different enterprise traffic classes can be mapped into the four traffic classes offered by a service provider. In the example, there is no streaming video traffic. The following four traffic classes are offered by the service provider Controlled Latency A traffic class for all real-time traffic. The controlled latency class admits packets marked with CS5 and Expedited Forwarding (EF). Controlled Load 1 A traffic class for all highly bursty traffic. The controlled...

Example Class Based Shaping with CBWFQ

Class-based shaping can be used in combination with CBWFQ. The shape rate provides a maximum rate limit for the traffic class, while the bandwidth statement within CBWFQ provides a minimum bandwidth guarantee. In the example, the cust1 traffic class is shaped to an average rate of 384 kbps, and is guaranteed a minimum of 256 kbps by the CBWFQ bandwidth statement. Because the Bc and Be are not specified, they will be automatically calculated by the Cisco IOS software. Example Class-Based Shaping...

Example Configuring the AutoQoS Enterprise Feature on a High Speed Serial Interface

In the example, the AutoQoS Enterprise feature is configured on the high-speed serial interface s1 1 Router> enable Router configure terminal Router(config) interface s1 1 Router(config-if) bandwidth 1540 Router(config-if) ip address 10.10.100.1 255.255.255.0 Router(config-if) auto discovery qos Router(config-if) auto qos Router(config-if) exit This topic describes how to use Cisco IOS commands to examine and monitor a network configuration after AutoQoS has been configured. When the AutoQoS...

Example Configuring the AutoQoS VoIP Feature on a High Speed Serial Interface

In the example, the AutoQoS VoIP feature is configured on the high-speed serial interface s1 2 Router> enable Router configure terminal Router(config) interface s1 2 Router(config-if) bandwidth 1540 Router(config-if) auto qos voip Router(config-if) exit Global configuration command. All the global QoS settings are applied to all ports in the switch. Prompt displays the CLI for the port-based automatic QoS commands currently supported. Console> (enable)set qos autoqos QoS is enabled All...

Example LLQ Example on the Enterprise WAN Edge Router

Priority percent 18 class VIDEO-CONF priority percent 15 class STREAM-VIDEO bandwidth percent 10 match ip dscp cs6 class-map match-all VOICE match ip dscp ef class-map match-all VIDEO-CONF match ip dscp af41 class-map match-all STREAM-VIDEO match ip dscp cs4 class-map match-all MISSION-CRIT match ip dscp 25 class-map match-any VOICE-CONTROL match ip dscp cs3 match ip dscp af31 class-map match-all TRANSACT match ip dscp af21 class-map match-all NETWORK-MGMT match ip dscp cs2 class-map match-all...

Frame Relay DE bit

Classification using MQC is accomplished by specifying a traffic match criteria within a configured class map for each different service class. In order for QoS mechanisms to use the class map, the map must be referenced through the use of a policy map, which is subsequently applied to an inbound or outbound interface as a service policy. In older Cisco IOS software releases, the router classified a packet against every individual QoS feature. This resulted in additional processing overhead,...

Frame Relay Voice Adaptive Traffic Shaping and Fragmentation

This topic describes Frame Relay voice-adaptive traffic shaping and fragmentation. This topic describes Frame Relay voice-adaptive traffic shaping and fragmentation. To address the needs of voice traffic in a Frame Relay network in which shaping is desired only when voice is present, but otherwise bursting to port-speed is desired, you can configure the FR-VATS feature. This feature was introduced in Cisco IOS Release 12.2(15)T. FR-VATS monitors the Frame Relay permanent virtual circuit (PVC),...

Hardware Queue TxQ Size

Routers determine the length of the hardware queue based on the configured bandwidth of the interface. The length of the hardware queue can be adjusted with the tx-ring-limit command. Reducing the size of the transmit ring has two benefits - It reduces the maximum amount of time that packets wait in the FIFO queue before being transmitted. - It accelerates the use of QoS in the Cisco IOS software. Improper tuning of the hardware queue may produce undesirable results - Long TxQ may result in...

How Can a QoS Service Class Be Used to Implement a QoS Policy

Specifying an administrative policy for QoS requires that a specific set of service classes be defined. QoS mechanisms are uniformly applied to these individual service classes to meet the requirements of the administrative policy. Because the application of QoS mechanisms is applied to different service classes and used to differentiate between applications, users, and traffic, the service class is a key component of a successful QoS implementation. There are many different methods in which...

Impact of an Internet Worm Attack

The figure illustrates the impact that a worm can cause due to its speed of propagation, resulting in a DoS as it consumes network resources. In the example, a worm is introduced into the network via a laptop PC, which in turn infects an e-mail server, which results in the e-mail server infecting other servers, while the worm is propagated to all ends of the enterprise network. Without a QoS mitigation strategy, this example is very likely to happen. This topic describes the QoS tools that can...

Implementing QoS with AutoQoS

AutoQoS VoIP supported both in the LAN and WAN environments AutoQoS Enterprise supported on WAN interfaces Routers can deploy Enterprise QoS policy treatment for voice, video, and data traffic Switches can deploy QoS policy treatments for voice by a single command trust option is used to trust DSCP marking Depending on the platform, using Cisco AutoQoS VoIP or AutoQoS Enterprise, you can implement the QoS features that support VoIP traffic and data traffic without an in-depth knowledge of these...

In Best Effort networks propagation delay is fixed processing and queuing delays are unpredictable

The figure illustrates the impact that a network has on the end-to-end delay of packets going from one end of the network to the other. Each hop in the network adds to the overall delay because of these factors Propagation delay is caused by the speed of light traveling in the media for example, the speed of light traveling in fiber optics or copper media. Serialization delay is the time it takes to clock all the bits in a packet onto the wire. This is a fixed value that is a function of the...

Ip address command

Before configuring AutoQoS, you must meet these prerequisites Cisco Express Forwarding (CEF) must be enabled at the interface, ATM PVC, or Frame Relay DLCIs (point-to-point subinterfaces only). AutoQos uses NBAR to identify various applications and traffic types, and CEF is a prerequisite for NBAR. You must ensure that no QoS policies (service policies) are attached to the interface. AutoQoS cannot be configured if a QoS policy (service policy) is attached to the interface. AutoQoS classifies...

L2 Payload Compression Results

Compression increases throughput and decreases delay. Use hardware compression when possible. Examples Stacker, Predictor, MPPC. Compression increases throughput and decreases delay. Use hardware compression when possible. Examples Stacker, Predictor, MPPC. If no compression is used, the throughput is limited by the link bandwidth, and the average delay is influenced by the forwarding or buffering delay, the serialization, and the propagation delay. If compression is enabled even if the...

Lfi Mlp Frf12 and FRF11C

While many QoS mechanisms exist for optimizing throughput and reducing delay in network traffic, QoS mechanisms do not create bandwidth. QoS mechanisms optimize the use of existing resources, and enable the differentiation of traffic according to a policy. Link efficiency QoS mechanisms such as payload compression, header compression, and LFI are deployed on WAN links to optimize the use of WAN links. Payload compression increases the amount of data that can be sent through a transmission...

Life of a Low Priority FTP Packet

The low-priority FTP packet begins life as a very low-priority CoS 0, DSCP 0. Note The FTP packet is using TCP rather than UDP (which was used by the voice packet). All traffic arriving from the workstation attached to the IP Phone is set to be untrusted. As a result, the IP Phone will not accept any CoS marking done by the workstation and will remark the CoS to 0. This ensures that the voice traffic generated by the IP Phone will always receive priority treatment over any traffic generated by...

Link Efficiency Used to improve bandwidth efficiency through compression link fragmentation and interleaving

The main categories of tools used to implement QoS in a network are as follows Classification and marking The identifying and splitting of traffic into different classes and the marking of traffic according to behavior and business policies Congestion management The prioritization, protection, and isolation of traffic based on markings Congestion avoidance Discards specific packets based on markings to avoid network congestion. Policing and shaping Traffic conditioning mechanisms that police...

Mainly used for setting Layer 2 and Layer 3 QoS fields

The class-based policing configuration is an example of a multiaction class-based policing. In this case, all Kazaa2 traffic is policed to 56 kbps. All conforming traffic will be marked with a DSCP value of 8, and then transmitted. All exceeding traffic will be marked with a DSCP value of 0, and the CLP bit in the ATM header will also be set before it is transmitted. All violating traffic will be dropped. The multiaction feature was introduced in Cisco IOS Release 12.2(8)T and is primarily used...

Make sure the new configurations still conform to the design and implementation from the previous example

The same service policy will be configured in this example. In this case, however, DSCP-based classes of service are used. Remember that the DiffServ model itself provides defined traffic classes and their associated PHB. DiffServ-based classification is used in this example as follows Mission-critical class Marked using DSCP AF class 2, and should get 30 percent of an interface bandwidth Bulk class Marked using DSCP AF class 1, and should get 20 percent of the interface bandwidth Best-effort...

Methods for Implementing QoS Policy

This topic describes four different methods for implementing and managing a QoS policy. Just a few years ago, the only way to implement QoS in a network was by using the command-line interface (CLI) to individually configure QoS policies at each interface. This was a time-consuming, tiresome, and error-prone task that involved cutting and pasting configurations from one interface to another. Cisco introduced the MQC in order to simplify QoS configuration by making configurations modular. Using...

Module Summary Cont

Voice, video, and data have very different requirements and must be defined into traffic classes. Different methods to implement a QoS policy on Cisco devices include the following - Use existing CLI configuration mode - Use MQC-based QoS configuration - Use automated methods such as AutoQoS and QPM Converged IP networks must provide secure, predictable, measurable, and sometimes guaranteed services. QoS provides network administrators and architects with a set of techniques used to manage...

Monitoring the Frame Relay Voice Adaptive Feature

This topic describes monitoring the FR-VATS feature using Cisco IOS software commands. The show policy map command gives a static verification of the policy configuration only. No dynamic counters are included in its output. The following is a sample output WAN-EDGE show policy TRAFFIC-SHAPE Policy Map TRAFFIC-SHAPE Class class-default Traffic Shaping CIR 729600 (bps) Max. Buffers Limit 1000 (Packets) Bc 3648 Be 0 Voice Adapt Deactivation Timer 30 Sec Note The highlighted section in the example...

No differentiated drop

The simple tail-drop scheme does not work well in environments with a large number of TCP flows or in environments in which selective dropping is required. Understanding the network interaction between TCP stack intelligence and dropping is required to implement a more efficient and fair dropping scheme, especially in service provider environments. Tail drop has the following shortcomings When congestion occurs, dropping affects most of the TCP sessions, which simultaneously back off and then...

Objectives

Upon completing this lesson, you will be able to identify capabilities provided by AutoQoS Enterprise and configure QoS on a network using AutoQoS Enterprise. This ability includes being able to meet these objectives Explain how AutoQoS Enterprise is used to implement QoS policy Describe the router platforms on which AutoQoS Enterprise is supported Describe the prerequisites for using AutoQoS Enterprise Describe how AutoQoS Enterprise is configured on a router using CLI Describe how to use...

Packet Loss

This topic describes how packet loss can adversely impact QoS in a network and describes ways to manage packet loss so that QoS is not affected. Tail drops occur when the output queue is full. These are common drops, which happen when a link is congested. Tail drops occur when the output queue is full. These are common drops, which happen when a link is congested. Many other types of drops exist, usually the result of router congestion, that are uncommon and may require a hardware upgrade...

PEtoCE QoS for Frame Relay Access PE Outbound

Class-map match-all PREMIUM match ip dscp ef class-map match-all BUSINESS match ip dscp af31 af32 af33 bandwidth percent remaining 75 random-detect dscp-based class class-default bandwidth percent remaining 25 bandwidth percent remaining 25 random-detect dscp-based The figure shows the QoS configurations on the egress PE router outbound interface to implement the required QoS policy required for each of the three service provider traffic classes. In this case, a traffic policy called OUT-POLICY...

Policing drops or marks packets when a predefined limit is reached

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...

Policing vs Shaping

Incoming and outgoing directions Incoming and outgoing directions Out-of-profile packets are dropped Dropping causes TCP retransmits Supports packet marking or re-marking Less buffer usage (shaping requires an additional shaping queuing system) Out-of-profile packets are queued until a buffer gets full Buffering minimizes TCP retransmits Marking or re-marking not supported Shaping supports interaction with Frame Relay congestion indication Shaping queues excess traffic by holding packets...

Qavet1 Qavet 0998 Qt 0002

WRED does not calculate the drop probability using the current queue length, but rather uses the average queue length. The average queue length is constantly recalculated using two terms the previously calculated average queue size and the current queue size. An exponential weighting constant N influences the calculation by weighing the two terms, therefore influencing how the average queue size follows the current queue size, in this way For high values of N, the previous average becomes more...

QoS Baseline Classification Summary

The figure illustrates a QoS baseline recommendation for traffic classification and markings. In this example, the enterprise traffic is classified into 11 traffic classes including the following Five data classes (mission-critical, transactional, bulk, scavenger, best effort) One class for network management traffic One class for routing protocol traffic One class for voice traffic One separate class for voice call-signaling traffic One class for videoconferencing traffic One class for...

QoS Baseline Classification Summary Cont

A marking of CS3 is recommended for voice call-signaling traffic. However, some older versions of Cisco IP Phones and other Cisco IP telephony devices originally marked voice call-signaling traffic to AF31. A reevaluation of the relevant standard (RFC 2597, an Assured Forwarding PHB) led Cisco to change its call-signaling marking to CS3. A Class-Selector PHB is better suited to the needs of call signaling, given that an Assured Forwarding PHB allows for markdown and increased drop-preference of...

QoS in Catalyst 4000 Distribution SUPIII

- CoS value 4, 5 selects queue 3 Default mapping from CoS to DSCP and DSCP to CoS Class-based policing to ratelimit traffic The Catalyst 4500 has a total of four queues. You can configure the link bandwidth to be shared differently among the four transmit queues by assigning the minimum guaranteed bandwidth for each transmit queue. By default, all four queues are scheduled in a round-robin manner, with each queue having 25 percent of the link bandwidth. You can configure the transmit queue 3 on...

QoS Traffic Requirements Data

Different applications have different traffic characteristics. Different versions of the same application can have different traffic characteristics. Classify data into relative-priority model with no more than four to five classes Mission-Critical Apps Locally defined critical applications Transactional Interactive traffic, preferred data service Best-Effort Internet, e-mail, unspecified traffic Less-Than-Best-Effort (Scavenger) Napster, Kazaa, peer-to-peer applications Different applications...

QoS Traffic Requirements Videoconferencing

Minimum priority bandwidth guarantee required is - For example, a 384-kbps stream would require 460 kbps of bandwidth This topic summarizes the key points discussed in this module. This topic summarizes the key points discussed in this module. The different link efficiency mechanisms available in Cisco IOS software include class-based TCP and RTP header compression, Layer 2 payload compression, MLP link fragmentation and interleaving (MLP LFI), and Frame Relay Fragmentation (FRF. 12). You can...

QoS Trust Boundary in the LAN Classify and Mark Where

Personal Computer Frames are typically unmarked (CoS 0) unless NIC is 802.1P- or 802.1Q-capable If marked, IP Phone can (and by default does) reclassify CoS but not DSCP IP Phone Marks voice as Layer 2 CoS (default) or Layer 3 ToS or DSCP Reclassifies incoming PC data frames Access Layer Based on switch capabilities Accept or remap here Distribution Layer Example Catalyst 6000 Marks traffic Accepts CoS ToS Remaps CoS to ToS or DSCP Cisco QoS model assumes that the CoS carried in a frame may or...

Queuing on Catalyst Switches

Multiple queues protect the queue containing important traffic (voice) from drops. The number of queues available depends upon the switch model and port type. On some switches, drop thresholds can be assigned to each queue. On some switches, queues can have normal tail drop or WRED dropping. In a converged network, it is vital to ensure that voice traffic is not dropped. The use of multiple queues in Catalyst switches protects the queue containing important traffic (voice) from being dropped....

RED result

- TCP sessions slow down to the approximate rate of output-link bandwidth. - Average queue size is small (much less than the maximum queue size). - TCP sessions are desynchronized by random drops. RED is a dropping mechanism that randomly drops packets before a queue is full. The dropping strategy is based primarily on the average queue length that is, when the average size of the queue increases, RED will be more likely to drop an incoming packet than when the average queue length is shorter....

Released in Cisco IOS Release 12215T

The NBAR feature has these two components One component monitors applications traversing a network. The other component classifies traffic by protocol. In order to monitor applications traversing a network, protocol discovery must be enabled. The ability to classify traffic by protocol using NBAR and then to apply QoS to the classified traffic is configured using the MQC. Use the ip nbar protocol-discovery command to configure NBAR to keep traffic statistics for all protocols known to NBAR....

RSVP Interface Queuing

The figure outlines how RSVP data flows are allocated when RSVP is configured on an interface. The maximum bandwidth available on any interface is 75 of the line speed the rest is used for control plane traffic. When RSVP is configured on an interface, the option is to use the entire usable bandwidth or a certain configured amount of bandwidth. The default is for RSVP data flows to use up to 75 of the available bandwidth. The figure shows that when RSVP is configured, a priority queue is set up...

Service Provider SLA Example

The actual SLA offered by service providers may vary. The figure shows an example of a typical QoS SLA from an IP service provider. In this example, the service provider offers three service classes to the customer controlled latency, controlled load, an d best effort. The SLA guarantees in this example include the following For the controlled latency class A one-way delay of 40 ms that is guaranteed 90 percent of the time A jitter of 2 ms that is guaranteed 90 percent...

Step 3 Design Individual QoS Mechanisms

This figure shows the third requirement, consisting of the following BGP routes that are received into AS 12 from AS 73 will be marked with a community value of 12 17 on the point of presence (POP) router. Community propagation will have to be configured on the POP router so that the community value of 12 17, set on the POP router, will be propagated to the NAP router. All the BGP routes with a community of 12 17 in the IP routing table and the FIB table on the AS 12 NAP routers will contain...

Syntax Description

Number of an IP standard or extended ACL. For an IP standard ACL, the ACL index range is 1 to 99 and 1300 to 1999. For an IP extended ACL, the ACL index range is 100 to 199 and 2000 to 2699. Name of an IP standard or extended ACL or name of an extended MAC ACL. Note The ACL name must begin with an alphabetic character to prevent ambiguity with numbered ACLs. A name also cannot contain a space or quotation mark. List of up to eight DSCP values for each match statement to match against incoming...

The table lists the nonTCP and nonUDP protocols supported by NBAR NonTCP and NonUdp Nbar Supported Protocols

IP Encapsulating Security Payload (ESP 50) and Authentication Header (AH 51) Enhanced Interior Gateway Routing Protocol Although access lists can also be used to classify applications based on static port numbers, NBAR is easier to configure and can provide classification statistics that are not available when using access lists. The table contains the static IP protocols supported by NBAR. Static TCP and UDP NBAR Supported Protocols Dynamic Host Configuration Protocol Bootstrap Protocol...

Traffic exceeding the specified bandwidth is dropped if congestion exists otherwise policy is not used

When you specify the priority command for a class, it takes a bandwidth argument that gives maximum bandwidth in kbps. You use this parameter to specify the maximum amount of bandwidth allocated for packets belonging to the class configured with the priority command. The bandwidth parameter both guarantees bandwidth to the priority class and restrains the flow of packets from the priority class. priority bandwidth-kbps percent percentage burst priority bandwidth-kbps percent percentage burst...

Traffic Leaving Enterprise Network

Output QoS policy on CE controlled by service provider Service provider enforces SLA using the output QoS policy on CE Output policy uses queuing, dropping, and possibly shaping Elaborate traffic classification or mapping of existing markings Output QoS policy on CE not controlled by service provider Output QoS policy on CE not controlled by service provider Service provider enforces SLA using input QoS policy on PE Input policy uses policing and marking Elaborate traffic classification or...

Traffic Policing Example

Rate-limit file-sharing application traffic to 56 kbps. Do not rate-limit traffic from mission-critical server. Rate-limit file-sharing application traffic to 56 kbps. Do not rate-limit traffic from mission-critical server. You can use traffic policing to divide the shared resource (the upstream WAN link) between many flows. In this example, the router FastEthernet interface has an input traffic-policing policy applied to it, in which the mission-critical server traffic rate is not...

Treatment is identical to a network using only WRED

On Cisco IOS routers, ECN is an extension to WRED functionality. WRED is an active queue management mechanism that uses packet drops as a congestion indicator to endpoints. Packets are dropped by WRED based on the average queue length exceeding a specific set of predefined threshold values (minimum and maximum threshold). ECN is an extension to WRED, in that ECN marks packets instead of dropping them when the average queue length exceeds a specific threshold value. When ECN is configured with...

Use differentiated WRED to prevent congestion in all three classes

This example of CBWFQ with WRED focuses on a network that provides these three different service levels for three traffic classes Mission-critical class Marked with IP Precedence values 3 and 4 (3 is used for high-drop service, and 4 is used for low-drop service within the service class), and should get 30 percent of an interface bandwidth Bulk class Marked with IP Precedence values 1 and 2 (1 is used for high-drop service, and 2 is used for low-drop service), and should get 20 percent of the...

Using QoS Policies on VPN Interfaces

Tunnel interfaces support many of the same QoS features as physical interfaces. In VPN environments, a QoS service policy can be applied to the tunnel interface or to the underlying physical interface. The decision about whether to configure the qos pre-classify command depends on which header is used for classification. Classification defines the process of matching one or more fields in a packet header in Layer 2, 3, or 4, and then placing that packet in a group or class of traffic. Using...

Volume

Understanding Queuing Implementations_5-15 Congestion on Software Interfaces 5-21 Queuing Implementations in Cisco IOS 5-22 WFQ Insertion and Drop Policy 5-34 Benefits and Drawbacks of WFQ 5-44 Class-Based Weighted Fair Queuing 5-53 Configuring and Monitoring CBWFQ 5-61 Example Configuration of FIFO Queuing 5-63 Example Configuration of WFQ Queuing 5-63 Configuring and Monitoring LLQ 5-69 Example Calculating LLQ Bandwidth Required for VoIP 5-71 Configuring LAN Congestion Management_5-77 Queuing...

Weighted Round Robin

WRR overcomes the problem of having PQ starving out the lower priority queues. WRR scheduling prevents queues with a lower weight from being completely starved during periods of heavy high-priority traffic. Different weights are assigned to each queue. For example, in one scheduling round, the WRR scheduler will transmit - Three frames from a queue assigned weight 3 - Four frames from a queue assigned weight 4 WRR with an expedite queue When WRR is configured on a Catalyst 2950, the option...

WFQ Case Study Interface Congestion Cont

HQO is the maximum number of packets that the WFQ system can hold and HQO 10. HQO is the maximum number of packets that the WFQ system can hold and HQO 10. Absolute maximum (HQO 10) exceeded, new packet is the last in the TDM system and is dropped. Early dropping (of aggressive flows) should start when there are eight packets (congestive discard threshold) in the WFQ system. The example illustrates how WFQ can drop packets even if the WFQ system is still within the hold-queue limit. The...

Classification and Marking at the Data Link Layer Ethernet 8021Q Class of Service

Three bits used for CoS (802.1 P user priority) Three bits used for CoS (802.1 P user priority) 802.1P user priority field, also called CoS Focuses on support for QoS over LANs and 802.1Q ports Preserved through the LAN, not end to end 802.1P user priority field, also called CoS Focuses on support for QoS over LANs and 802.1Q ports Preserved through the LAN, not end to end The 802.1Q standard is an IEEE specification for implementing VLANs in Layer 2 switched networks. The 802.1Q specification...

Switch queuing capabilities are shown as

Two drop thresholds for each queue Two drop thresholds for each queue Different Cisco Catalyst switches offer these different queuing capabilities The number of queues per port The type of queues (priority or standard) The capability to have drop thresholds for a queue The number of drop thresholds per queue The type of drop thresholds (tail drop or WRED). When you view information on Cisco Catalyst switches, queuing information is displayed in an abbreviated format, as in these examples 2Q2T...

It will be there by 1030 am

Some applications, such as high-resolution video, require consistent, dedicated bandwidth to provide sufficient quality for viewers. IntServ was introduced to guarantee predictable network behavior for these applications. Because IntServ reserves bandwidth throughout a network, no other traffic can use the reserved bandwidth. Bandwidth that is unused, but reserved, is wasted. IntServ is similar to a concept known as hard QoS . With hard QoS, traffic characteristics such as bandwidth, delay, and...

Available in Cisco IOS Release 1224T

Dual-rate class-based policing was introduced in Cisco IOS 12.2(4)T. With dual-rate policing, traffic policing can be enforced according to two separate rates CIR and PIR. The use of these two rates can be specified, along with their corresponding values, by using two keywords, cir and pir, in the police command. The Bc and Be keywords and their associated arguments (conform-burst and peak-burst, respectively) are optional. If Bc is not specified, Bc (in bytes) will default to CIR 32, or 1500...

DSCP is backward compatible with IP precedence

At the network layer, IP packets are typically classified based on source or destination IP address, packet length, or the contents of the ToS byte. Link-layer media often changes as a packet travels from its source to its destination. Because a CoS field does not exist in a standard Ethernet frame, CoS markings at the link layer are not preserved as packets traverse non-trunked or non-Ethernet the network. Using marking at the network layer (Layer 3) provides a more permanent marker that is...

Configuring Single Rate Class Based Policing

Police avg-rate BC BE conform-action action exceed-action action violate-action action avg-rate Traffic rate in bps (8000 to 200,000,000) BC normal burst sets the size in bytes - Default is 1500 bytes, or CIR 32, whichever is higher Be Excess burst sets the size in bytes - transmit (default conform action) - drop (default exceed and violate action) - set-prec-transmit ip-precedence - set-mpls-exp-transmit mple-exp The MQC-based police command defines policing parameters for a specific traffic...

Example Dual Rate Token Bucket as a Piggy Bank

Using a dual-rate token bucket is like using two piggy banks, each with a different savings rate. However, you can only take out money from one of the piggy banks at a time. For example, you can save ten dollars per day into the first piggy bank (PIR peak spending rate 10 per day) and then at the same time, you can save five dollars per day into the second piggy bank (CIR normal average spending rate 5 per day). However, the maximum amount you can spend is 10 per day, not 15 per day, because...

The packet precedence has no effect on the dropping scheme

Wfq Weight Calculation

WFQ uses these two parameters that affect the dropping of packets The congestive discard threshold (CDT) is used to start dropping packets of the most aggressive flow, even before the hold-queue limit is reached. The hold-queue out limit (HQO) defines the maximum number of packets that can be in the WFQ system at any time. There are two exceptions to the WFQ insertion and drop policy, as follows If the WFQ system is above the CDT limit, the packet is still enqueued if the per-flow queue is...

Cisco Icons and Symbols

For additional information on Cisco terminology, refer to the Cisco Internetworking Terms and Acronyms glossary of terms at You are encouraged to join the Cisco Certification Community, a discussion forum open to anyone holding a valid Cisco Career Certification (such as Cisco CCIE , CCNA , CCD A , CCNP , CCDP , CCIP , or CCSPTM). It provides a gathering place for Cisco certified professionals to share questions, suggestions, and information about Cisco Career Certification programs and other...

Example Token Bucket as a Piggy Bank

Think of a token bucket as a piggy bank. Every day you can insert a dollar into the piggy bank (the token bucket). At any given time, you can only spend what you have saved up in the piggy bank. On the average, if your saving rate is a dollar per day, your long-term average spending rate will be one dollar per day if you constantly spend what you saved. However, if you do not spend any money on a given day, you can build up your savings in the piggy bank up to the maximum limit that the piggy...