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...

All packets marked with one of the selected IP precedence values are matched by this class map

Class-map Mission-Critical match ip precedence 3 4 class-map Transactional match ip precedence 1 2 A much faster method of classification is by matching the IP precedence. Up to four separate IP precedence values or names can be used to classify packets based on the IP Precedence field in the IP header on a single match-statement line. The figure contains a mapping between IP precedence values and names. The running configuration, however, only shows IP precedence values (not names). match ip...

All packets received through the selected input interface are matched by this class map

Match input-interface Ethernet0 0 match input-interface Ethernet0 1 match input-interface FastEthernet1 0 match input-interface FastEthernet1 1 match input-interface Serial2 0 match input-interface Serial2 1 match input-interface Serial2 2 match input-interface Serial2 3 As shown in the example in the figure, a packet can also be classified based on the input interface. In the first class-map example, called Ethernets, the match input-interface will match any packet that arrives on either the...

Ambiguous path

Teardown messages RSVP teardown messages remove the path and reservation state without waiting for the cleanup timeout period. 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 Path-teardown messages delete the path state (which deletes the reservation state), travel toward all receivers downstream from the point of initiation, and are...

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...

Applies a policy map defined by the policymap command to the input of a particular interface

Permit host 0001.0000.0001 host 0002.0000.0001 class-map macclassl match access-group name maclistl policy-map macpolicyl class macclassl set ip dscp 26 interface gigabitethernet0 l switchport mode trunk mls qos trust cos service-policy input macpolicyl The last step in configuring a policy is to apply the policy to the interface. In the example, an extended access list has been created for a MAC address, maclistl. A class map, macclassl, has been created that will match any MAC address...

Applying Congestion Avoidance

RED is most useful in enterprise and service provider networks on output interfaces where congestion is expected to occur. Edge routers or switches typically classify and mark packets as the packets enter the network. Congestion avoidance mechanisms can use these packet markings to indicate a set of drop criteria for a traffic stream. Congestion avoidance mechanisms are also applicable to the campus or LAN environment. In these networks, congestion avoidance is best used on interfaces that...

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...

Attaching Service Policies to Interfaces

This topic describes the MQC commands used to attach a service policy to an interface. Attaching Service Policies to Interfaces service-policy input output policy-map-name Attaches the specified service policy map to the input or output interface interface Serial0 0 service-policy output PM bandwidth 2000 class class-default bandwidth 6000 Use the service-policy interface configuration command to attach a traffic policy to an interface and to specify the direction in which the policy should be...

Automation with Cisco AutoQoS Routers Diff Serv Functions Automated

Cisco IOS Catalyst Behavior Software QoS Feature Set Layer 3 and Layer 2 attributes to categorize packets into a class. Set Layer 3 and Layer 2 attributes to categorize packets into a class. Provide EF treatment to voice and Best-Effort treatment to data. Shape to CIR to prevent burst and smooth traffic to configured rate. Reduce the VoIP bandwidth requirement. Reduce jitter experienced by voice packets. AutoQoS performs these functions in a WAN Automatically classifies Real-Time Transport...

Available in Cisco IOS Release 12213T

Policy-map police1 class bulk-ftp police cir percent 20 pir percent 40 conform-action set-dscp-transmit af11 exceed-action set-dscp-transmit 0 violate-action drop interface Ethernet 0 0 service-policy input policel interface Serial 0 0 service-policy input police1 The percentage-based policing feature was introduced in Cisco IOS Release 12.2(13)T. Before this feature, traffic policing was configured on the basis of a user-specified amount of bandwidth available on the interface. Policy maps...

Before Converged Networks

Traditional data traffic characteristics First-come, first-served access Mostly not time-sensitive - delays OK Brief outages are survivable Order Entry, Finance, Manufacturing, HR, Training, Other Traditional data traffic characteristics First-come, first-served access Mostly not time-sensitive - delays OK Brief outages are survivable Order Entry, Finance, Manufacturing, HR, Training, Other Before networks converged, network engineering focused on connectivity. The rates at which data came onto...

Behavior of a TCP Receiver

Receiver schedules an ACK on receipt of next message. TCP acknowledges the next segment it expects to receive, not the last segment it received. - In the example, N+1 is blocked, so the receiver keeps acknowledging N+1 (the next segment it expects to receive). When the receiver receives a data segment, the receiver checks that data segment sequence number (byte count). If the data received fills in the next sequence of numbers expected, the receiver indicates that the data segment was received...

Benefits and Drawbacks of WFQ

Simple configuration (classification does not have to be configured) Guarantees throughput to all flows Drops packets of most aggressive flows Supported on most platforms Supported in all IOS versions Multiple flows can end up in one queue Does not support the configuration of classification Cannot provide fixed bandwidth guarantees Complex classification and scheduling mechanisms Simple configuration (no manual classification is necessary) Guarantees throughput to all flows Drops packets of...

Best Effort

- Best-effort class sent to CBWFQ - Whatever is left 25 of remaining bandwidth after LLQ has been serviced - WRED configured to optimize TCP throughput The figure shows the required PHB for each of the three traffic classes supported by the service provider. For the premium (V olP) traffic class, the VoIP packets will be marked with EF and will go into the LLQ with these parameters The LLQ will be policed and have a maximum bandwidth of 25 percent of the CIR. All excess traffic will be dropped....

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...

Business Security Threat Evolution

Macro viruses, Trojans, e-mail, single-server DoS, limited targeted hacking Multi-server DoS, DDoS, blended threats (Worm + Virus + Trojan), turbo threats, massive worm-driven DDoS, negative payload viruses, worms, and Trojans In recent years, there has been an increase in the frequency of DoS and worm attacks, and an increase in their sophistication. DoS or worm attacks fall into two main classes spoofing attacks and flooding attacks. In spoofing attacks, the attacker pretends to provide a...

Campus QoS Implementation

A robust, modern switching design is a requirement. A robust, modern switching design is a requirement. Buffer management is more of a concern than bandwidth management. Multiple queues are required on all interfaces to prevent Tx queue congestion and drops. Voice traffic should always go into the highest priority queue. Trust Cisco IP Phone CoS setting but not the PC CoS setting. Classify and mark traffic as close to the source as possible. Use class-based policing to rate-limit certain...

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...

Catalyst Switches

On the 3550 Catalyst switches, the default scheduling method is WRR with 25 percent of bandwidth per queue by default. You can assign CoS values to queues during configuration. The default CoS-to-queue assignment is as follows CoS 6 to 7 placed in queue 4 CoS 4 to 5 placed in queue 3 CoS 2 to 3 placed in queue 2 CoS 0 to 1 placed in queue 1 The switches support WRR scheduling, and WRR with a priority queue, as follows The WRR scheduling algorithm ensures that lower-priority packets are not...

Causes jitter bursts or packet trains temporarily fill the queue

Although FIFO queuing might be regarded as the fairest queuing mechanism, it has these FIFO is extremely unfair when an aggressive flow contests with a fragile flow. Aggressive flows send a large number of packets, many of which are dropped. Fragile flows send a modest number of packets and most of them are dropped because the queue is always full due to the aggressive flow. This type of behavior is called starvation. Short or long bursts cause a FIFO queue to fill. Packets entering an...

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...

CBWFQ Architecture

Supports multiple classes (depending on platform) Supports multiple classes (depending on platform) CBWFQ supports multiple class maps (the number depends upon the platform) to classify traffic into its corresponding FIFO queues. Tail drop is the default dropping scheme of CBWFQ. You can use weighted random early detection (WRED) in combination with CBWFQ to prevent congestion of a class. The CBWFQ scheduler is used to guarantee bandwidth that is based on the configured weights. Note Currently,...

CBWFQ Architecture Classification

Availability of certain classification options depends on the Cisco IOS version. Some classification options depend on type of interface and encapsulation where service policy is used. - Matching on Frame Relay discard eligible bits can only be used on interfaces with Frame Relay encapsulation. - Matching on MPLS experimental bits has no effect if MPLS is not enabled. - Matching on ISL priority bits has no effect if ISL is not used. You can use any...

CBWFQ Architecture Insertion Policy

Each queue has a maximum number of packets that it can hold (queue size). The maximum queue size is platform-dependent. After a packet is classified to one of the queues, the router will enqueue the packet if the queue limit has not been reached (tail drop within each class). WRED can be used in combination with CBWFQ to prevent congestion of the class. CBWFQ reserves multiple FIFO queues in the WFQ system. The default queue limit is 64 (tail drop) and can be configured with WRED (weighted...

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 AutoQoS with Cisco Works QPM

Use AutoQoS Enterprise to configure routers Use QPM to manage network-wide QoS for multiple devices. Use QPM to manage network-wide QoS for multiple devices. Customers can more easily provision and manage successful QoS deployments using Cisco AutoQoS together with QPM. Cisco AutoQoS provides QoS provisioning for individual routers and switches, simplifying deployment and reducing human error. CiscoWorks QPM provides centralized QoS design, administration, and traffic monitoring that scales to...

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...

Citrix ICA Interdependent Computing Architecture

New features are usually added to new versions of the Cisco IOS software. NBAR is the first mechanism that supports dynamic upgrades without having to change the Cisco IOS version or restart a router. PDLMs contain the rules that are used by NBAR to recognize an application and can be used to bring new or changed functionality to NBAR. You can load an external PDLM at run time to extend the NBAR list of recognized protocols. You can use PDLMs to enhance an existing protocol recognition...

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 QoS Mib CbqoSMIB

Provides read access to configuration and statistical information for MQC-based QoS policies Provides MQC configuration information and application statistics Provides CBQoS statistics on a per-policy, per-interface, or PVC basis Allows monitoring of pre- and post-policy bit rates on a device Provides read access to configuration and statistical information for MQC-based QoS policies Provides MQC configuration information and application statistics Provides CBQoS statistics on a per-policy,...

Class Based RTP Header Compression

Most of the information in the headers (IP, UDP, and RTP) is static throughout the session. IP (20 bytes), UDP (8 bytes), and RTP (12 bytes) use 40 bytes. RTP header compression can squeeze these three headers into 2 or 4 bytes. Class-based RTP header compression allows compression on a traffic class. Class-based RTP header compression is configured via MQC. RTP is the standard protocol (RFC 1889) for the transport of real-time data. RTP is intended to provide...

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...

Classbased TCP header compression is configured via MQC

In TCP header compression, the IP and TCP headers, which normally use 20 bytes each, are reduced to a session index, and the variable part of the header. With all optimizations, the combined header length of 40 bytes can be reduced to a 3- to 5-byte compressed header. After you configure a class within a policy map, class-based TCP header compression occurs on a per-class basis. Policy maps are created using the MQC. Attach the policy maps to an interface by using the service-policy command....

Classification

Classification is the identifying and splitting of traffic into different classes. Classification is the identifying and splitting of traffic into different classes. Traffic can be classed by various means, including the DSCP. Modular QoS CLI allows classification to be implemented separately from policy. Classification is the identifying and splitting of traffic into different classes. In a QoS-enabled network, all traffic is classified at the input interface of every QoS-aware device. Packet...

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 can also be performed using MQC class maps and policy maps

Create an IP standard or extended ACL for IP traffic, or a Layer 2 MAC ACL for non-IP traffic. 2. Create a class map and define the match criteria to classify traffic. 3. Create a service policy to perform the appropriate QoS action (mark, police, and so on). 4. Apply the service policy to a switch interface. Create a class map by using the class-map global configuration command. The class-map global configuration command is used to isolate a specific traffic flow (or class) from all other...

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 The IEEE 802.1P specification specifies a standard for delivering QoS in LANs. Packets are marked with three CoS bits where CoS values range from zero for low priority to seven for high priority. CoS can only be applied on trunks because VLAN trunking encapsulations designate fields with available space to carry CoS bits. There are currently two widely deployed trunking protocols that can transport CoS markings, as follows ISL frame...

Class Selector IP Precedence PHB

These PHBs are defined by IETF standards Default PHB Used for Best-Effort service (bits 5 to 7 of DSCP 000) Expedited Forwarding (EF) PHB Used for low-delay service (bits 5 to 7 of DSCP 101) Assured Forwarding (AF) PHB Used for guaranteed bandwidth service (bits 5 to 7 of DSCP 001, 010, 011, or 100) Class-selector PHB Used for backward compatibility with non-DiffServ-compliant devices (RFC 1812-compliant devices bits 2 to 4 of DSCP 000 )

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...

Compress IP packet headers

The best way to increase bandwidth is to increase the link capacity to accommodate all applications and users, with some extra bandwidth to spare. Although this solution sounds simple, increasing bandwidth is expensive and takes time to implement. There are often technological limitations in upgrading to a higher bandwidth. Another option is to classify traffic into QoS classes and prioritize traffic according to importance. Voice and business-critical traffic should get sufficient bandwidth to...

Compression

Layer 2 payload compression squeezes Layer 2 payloads (the entire Layer 3 packet). Layer 2 payload compression increases the throughput and decreases the latency in transmission, because smaller packets (with compressed payloads) take less time to transmit than the larger, uncompressed packets. Layer 2 payload compression is performed on a link-by-link basis. Header compression methods work by not transmitting repeated information in packet headers throughout a session. The two peers on a PPP...

Configurable queue weight

On the Catalyst 2950 series switches, the default scheduling method is strict priority. Strict priority scheduling is based on the priority of queues. Packets in the high-priority queue always transmit first packets in the low-priority queue do not transmit until all the high-priority queues become empty. CoS values can be assigned to queues during configuration. The default CoS-to-queue assignment is CoS 6 to 7 placed in queue 4 CoS 4 to 5 placed in queue 3 CoS 2 to 3 placed in queue 2 CoS 0...

Configuring and Monitoring Class Maps

This topic describes the Cisco IOS MQC commands required to configure and monitor a class map. Use the class-map global configuration command to create a class map and enter the class-map configuration mode. A class map is identified by a case-sensitive name therefore, all subsequent references to the class map must use exactly the same name. At least one match command should be used within the class-map configuration mode (match none is the default). The description command is used for...

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 Class Based Header Compression

Headers exist on almost every communication layer of the OSI stack. When data is sent between workstations, headers will typically be applied at the session, transport, network, and data-link layers. Real-Time Transport Protocol (RTP) is a protocol for the transport of real-time data. RTP includes a data portion and a header portion. The data portion of RTP is a thin protocol that provides support for the real-time properties of applications, such as continuous media, including timing...

Configuring Class Based Policing

Cisco IOS software supports two different traffic-policing mechanisms committed access rate (CAR) and class-based policing. CAR is an older Cisco traffic-policing feature, and class-based policing is a newer Cisco traffic-policing mechanism based on the modular quality of service (QoS) command-line interface (CLI), or MQC. Cisco recommends that you use MQC features when possible to implement QoS in the network. You should avoid using traffic-policing configurations with CAR, because no new...

Configuring Classification Using a UDP Port Range

Match ip rtp starting-port-number port-range Use this command to implement classification equal to IP RTP Priority. All UDP packets with source or destination port numbers within the specified range are matched. Range is between the starting-port (values from 2000 to 65535) and the sum of the starting-port and the port-range (values from 0 to 16383). The command should be used in combination with class-based low-latency queuing to implement RTP Priority using MQC. IP RTP Priority was introduced...

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 Frame Relay Adaptive Class Based Shaping

This topic describes the Cisco IOS commands that are required to configure Frame Relay adaptive class-based shaping on Frame Relay interfaces. Configuring Frame Relay Adaptive Class-Based Shaping Adapts the shaping rate when BECN bits are received. min-rate Each BECN bit causes the shaping rate to be reduced to three-quarters of the previous rate but not below the min-rate. This command has effect only if used on Frame Relay interfaces. Responds to FECN bits by creating test frames in 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 LANBased Classification and Marking

This topic describes the Cisco IOS commands that are required to configure LAN-based classification and marking. The figure shows some of the QoS configuration commands that are necessary for Catalyst 2950 switches. The defaults for its interfaces are as follows Pass-through mode is disabled. Trusted boundary is disabled. mls qos trust cos pass-through dscp device cisco-phone dscp

Configuring MLP with Interleaving

This topic describes the Cisco IOS commands required to configure MLP with interleaving. To configure MLP with interleaving, you must perform these configuration steps Step 17 Enable MLP on a PPP interface. Step 18 On the multilink interface, enable interleaving within MLP. Step 19 In the multilink interface configuration, specify the maximum fragment size by specifying the maximum desired serialization delay in ms. The ppp multilink command enables MLP on a PPP interface. The ppp multilink...

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...

Configuring NBAR for Stateful Protocols Cont

Match protocol rtp audio video payload-type payload-string Stateful mechanism to identify real-time audio and video traffic Differentiate on the basis of audio and video codecs The match protocol rtp command has these options - audio Match by payload-type values 0 to 23, reserved for audio traffic - video Match by payload-type values 24 to 33, reserved for video traffic - payload-type Specifies matching by a specific payload-type value, providing more granularity than the audio or video options...

Configuring NBAR for Stateful Protocols Example

On the input interface, three class maps have been created voice-in, videoconferencing-in, and interactive-in. The voice-in class map will match the RTP audio protocol the videoconferencing-in class map will match the RTP video protocol and the interactive-in class map will match the Citrix protocol. The policy map class mark will then do the following If the packet matches the voice-in class map, the packet differentiated services code point (DSCP) field will be set to Expedited Forwarding...

Configuring NBAR for Static Protocols Example

HTTP is a static protocol using a well-known port number 80. However, other port numbers may also be in use. The ip nbar port-map command will inform the router that other ports are also used for HTTP. HTTP is a static protocol using a well-known port number 80. However, other port numbers may also be in use. The ip nbar port-map command will inform the router that other ports are also used for HTTP. HTTP is often used on other port numbers. The example shows the usage of the ip nbar portmap...

Configuring QoS Preclassify

Enables the QoS preclassification feature. This command is restricted to tunnel interfaces, virtual templates, and crypto maps. Introduced for Cisco 2600 and 3600 in Cisco IOS Release 12.2(2)T. GRE and IPIP Tunnels router(config) interface tunnelO router(config-if) qos pre-classify router(config) interface virtual-templatel router(config-if) qos pre-classify router(config) crypto map secured-partner router(config-crypto-map) qos pre-classify The qos pre-classify Cisco IOS command enables the...

Configuring Voice Adaptation with Endto End Fragmentation on the Interface

Interface serialO encapsulation frame-relay frame-relay fragmentation voice-adaptive deactivation 30 (FR-VATS + FRF.12) frame-relay interface-dlci 100 class voice-adaptive-class (Binds voice_adaptive_class to the DLCI) frame-relay fragment 80 end-to-end (FRF.12 fragment for 384 kbps PVC on the interface) class-map match-all voice match access-group 102 class-map match-all data match access-group 101 policy-map VOICE-TRAFFIC-SHAPING class voice priority 10 (Strict Priority) class data bandwidth...

Configuring Voice Adaptation with Endtoend Fragmentation Through a Map Class

Interface serial0 encapsulation frame-relay frame-relay fragmentation voice-adaptive deactivation 30 (FR-VATS + FRF.12) frame-relay interface-dlci 100 class voice-adaptive-class (Binds voice_adaptive_class to the DLCI) map-class frame-relay voice-adaptive-class frame-relay fragment 80 (FRF.12 fragment for 384 kbps PVC through the map-Class) service-policy output TRAFFIC-SHAPE (Embeds FR-VATS Feature to map-class) class-map match-all voice match access-group 102 class-map match-all data match...

Configuring WRR on Catalyst 2950 Switches

This topic describes the commands required to configure WRR on the Catalyst 2950 switch. Use the wrr-queue bandwidth global configuration command to assign WRR weights to the four CoS priority queues on the Catalyst 2950 switch. Use the no form of this command to disable the WRR scheduler and enable the strict priority scheduler. For weight 1, weight 2, and weight 3, the range is 1 to 255. The range for weight 4 is 0 to 255. Queues 1, 2, and 3 can be configured for WRR scheduling and queue 4...

Congestion and Queuing

Congestion can occur at any point in the network where there are points of speed mismatches, aggregation, or confluence. Congestion can occur at any point in the network where there are points of speed mismatches, aggregation, or confluence. Queuing manages congestion to provide bandwidth and delay guarantees. Congestion can occur anywhere within a network where speed mismatches (for example, a GigabitEthernet link feeding a FastEthernet link), aggregation (for example, multiple...

Congestion Avoidance

Congestion avoidance may randomly drop packets from selected queues when previously defined limits are reached. Congestion avoidance may randomly drop packets from selected queues when previously defined limits are reached. By dropping packets early, congestion avoidance helps prevent bottlenecks downstream in the network. Congestion avoidance technologies include random early detection and weighted random early detection. Congestion-avoidance mechanisms monitor network traffic loads in an...

Congestion on Software Interfaces

This topic describes how congestion occurs on software interfaces. This topic describes how congestion occurs on software interfaces. Subinterfaces and software interfaces do not have their own separate transmit (Tx) ring therefore, no congestion can occur. These interface types include dialers, tunnels, and Frame Relay subinterfaces, and will only congest when their main hardware interface Tx ring congests. The Tx ring state is an indication of congestion for software interfaces. Software...

Consistency

- Enables automatic, seamless interoperability among all QoS features and parameters across a network topology -LAN, MAN, and WAN Cisco AutoQoS simplifies and shortens the QoS deployment cycle in these five major aspects Application Classification AutoQoS leverages intelligent classification on routers using Cisco network-based application recognition (NBAR) to provide deep and stateful packet inspection. AutoQoS uses Cisco Discovery Protocol (CDP) for voice packets to ensure that the device...

Controlled load

There are three types of QoS services offered by RSVP Best effort, guaranteed rate, and controlled load Best effort No QoS at all, just first in-first out. Guaranteed rate The RSVP-enabled routers try to guarantee the worst-case delay that will be incurred by the flow when traveling across the network. 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....

Converged Networks Quality Issues

Telephone Call I cannot understand you your voice is breaking up. Telephone Call I cannot understand you your voice is breaking up. Teleconferencing The picture is very jerky. Voice not synchronized. Brokerage House I needed that information two hours ago Where is it Call Center Please hold while my screen refreshes. With inadequate preparation of the network, voice transmission is choppy or unintelligible. Gaps in speech are particularly troublesome where pieces of speech are interspersed with...

Converged Networks Quality Issues Cont

Lack of bandwidth Multiple flows compete for a limited amount of bandwidth. End-to-end delay (fixed and variable) Packets have to traverse many network devices and links that add up to the overall delay. Variation of delay (jitter) Sometimes there is a lot of other traffic, which results in more delay. Packet loss Packets may have to be dropped when a link is congested. The four big problems facing converged enterprise networks are as follows Bandwidth capacity Large graphics files, multimedia...

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.

Course Flow

Introduction to Modular QoS CLI and AutoQoS (Cont. Introduction to Modular QoS CLI and AutoQoS The schedule reflects the recommended structure for this course. This structure allows enough time for the instructor to present the course information and for you to work through the lab activities. The exact timing of the subject materials and labs depends on the pace of your specific class.

Course Goal

To identify, describe, and correctly implement the appropriate QoS mechanisms required to create an effective administrative policy providing QoS. Implementing Cisco Quality of Service (QOS) Upon completing this course, you will be able to meet these objectives Explain the need to implement QoS and methods for implementing and managing QoS Identify and describe different models used for ensuring QoS in a network and explain key QoS mechanisms used to implement the models Explain the use of MQC...

Data Plane Policing

This topic describes how to use policing and the scavenger class to protect the data plane. Data Plane policing is the actual policing of data traffic. Understanding what is a normal profile behavior for users and servers and what is not is key in setting up policers to remark and drop packets. Out-of-profile behavior could be categorized by the increase in data traffic as a worm is being propagated over the enterprise network. Normal profile behavior could be what is expected from end-user...

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...

Deficit Round Robin

Solves problem with some implementations of WRR Keeps track of the number of extra bytes dispatched in each round the deficit Adds the deficit to the number of bytes dispatched in the next round Problem resolved with deficit round robin - Packet sizes of 1500, 1499, and 1500 - Total sent in round 4499 bytes - Deficit (4499 - 3000) 1499 bytes - On the next round send only the (threshold - deficit) (3000 - 1499) 1501 bytes Deficit round robin is an implementation of the WRR algorithm developed...

Deficit round robin with a priority queue for Cisco 12xxx routers

The figure shows these available software queuing technologies A Cisco implementation of the priority queuing algorithm Allows four queues to be used for prioritization (high, medium, normal, low) Allows for a variety of classification, including source IP address, destination IP address, IP precedence, and differentiated services code point (DSCP) A Cisco implementation of weighted round robin (WRR) Allows up to 16 queues to be used for traffic classification Allows for a variety of...

Define QoS Policies for Classes

What will be done to this traffic Defines a policy map, which configures the QoS features associated with a traffic class previously identified using a class map. Where will this policy be implemented Attaches a service policy configured with a policy map to an interface. Implementing QoS by using the MQC consists of three steps Step 4 Configure classification by using the class-map command. Step 5 Configure traffic policy by associating the traffic class with one or more QOS features using the...

Defines trust boundary to ensure simple classification and entry to a queue

The LLQ priority scheduler guarantees both low-latency propagation of packets and bandwidth to high-priority classes. Low latency is achieved by expediting traffic using a priority scheduler. Bandwidth is also guaranteed by the nature of priority scheduling, but is policed to a user-configurable value. The strict PQ scheme allows delay-sensitive data such as voice to be dequeued and sent first that is, before packets in other queues are dequeued. Delay-sensitive data is given preferential...

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...

Describe QoS SLA

Explain the typical network requirements within each functional block (campus LAN, WAN edge, service provider backbone, and branch) that makes up an end-to-end network Explain the best-practice QoS implementations and configurations within a campus LAN Explain the best-practice QoS implementations and configurations on WAN CE and PE routers Explain the best-practice QoS implementations and configurations on the service provider IP core and PE routers

Destination address

The concept of trust is key for deploying QoS. When an end device (such as a workstation or an IP Phone) marks a packet with class of service (CoS) or DSCP, a switch or router has the option of accepting or not accepting values from the end device. If the switch or router chooses to accept the values, the switch or router trusts the end device. If the switch or router trusts the end device, it does not need to do any reclassification of packets coming from that interface. If the switch or...

Determine required response time

The first step in implementing QoS is identifying the traffic on the network and determining QoS requirements for the traffic. The next step is determining the QoS problems of users. Measure the traffic on the network during congested periods. Conduct CPU utilization assessment on each of their network devices during busy periods to determine where problems might be occurring. Next, determine the business model and goals, and obtain a list of business requirements, in order to define the number...

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...

Diff Serv backbone is better

Two of the IP backbone design methods include a best-effort backbone with overprovisioning and a DiffServ backbone. The more traditional approach is to use a best-effort backbone with overprovisioning. However, to meet the application needs of today (VoIP, videoconferencing, e-learning, and so on), deploying a DiffServ backbone and offering different SLAs for the different traffic classes can greatly reduce the cost and improve the delay, jitter, and packet loss and meet network QoS...

Displays all class maps and their matching criteria

The show class-map command lists all class maps with their match statements. The show class-map command with a name of a class map displays the configuration of the selected class map. The example of show class-map in the illustration shows three class maps class-3 will match any packet to access-group 103. class-2 matches IP packets. class-1 matches any input from interface Ethernet 1 0.

Displays detailed information about the WFQ system of the selected interface

Input queue 0 75 0 (size max drops) Total output drops 0 Queueing strategy weighted fair Output queue 2 1000 64 0 (size max total threshold drops) Conversations 2 4 256 (active max active max total) Reserved Conversations 0 0 (allocated max allocated) (depth weight discards tail drops interleaves) 1 4096 0 0 0 Conversation 124, linktype ip, length 580 source 193.77.3.244, destination 20.0.0.2, id 0x0166, ttl 254, TOS 0 prot 6, source port 23, destination port 11033 (depth weight discards tail...

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 information about the Frame Relay fragmentation

The show frame-relay fragment command displays information about the FRF. 12 Frame Relay fragmentation process. The fragment type will always display end-to-end because this is the only type presently supported on Cisco IOS software. In addition to fragment type, the fragment size in bytes and associated DLCI is displayed.

Displays information about the indicated policy map including the configuration of all classes for a specified service

Router> show policy-map shape-cbwfq CIR 384000 (bps) Max. Buffers Limit 1000 (Packets) Bandwidth 256 (kbps) Max Threshold 64 (packets) The show policy-map command displays the policy-map configuration. The output represents the CBWFQ in conjunction with the class-based shaping configuration example shown earlier, in which the custl traffic class is shaped to an average rate of 384 kbps, with a default buffer limit of 1000 packets and a minimum bandwidth guarantee of 256 kbps.

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...