© 2006 Cisco Systems, Inc. All rights reserved.ONT v Implement the DiffServ QoS Model Configuring CBWFQ and LLQ

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Describing Advanced Queuing Mechanisms

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Queuing Methods Combined Basic methods are combined to create more versatile queuing mechanisms.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Class-Based Weighted Fair Queuing

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Class-Based Weighted Fair Queuing CBWFQ is a mechanism that is used to guarantee bandwidth to classes. CBWFQ extends the standard WFQ functionality to provide support for user-defined traffic classes: –Classes are based on user-defined match criteria. –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.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v CBWFQ Architecture and Benefits

© 2006 Cisco Systems, Inc. All rights reserved.ONT v CBWFQ Architecture

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Classification Classification uses class maps. 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. For example: –Matching on Frame Relay discard-eligible bits can be used only 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.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Scheduling CBWFQ guarantees bandwidth according to weights assigned to traffic classes. Weights are internally calculated from bandwidth or its percentage. Bandwidth availability can be defined by specifying: –Bandwidth (in kbps) –Percentage of bandwidth (percentage of available interface bandwidth) –Percentage of remaining available bandwidth One service policy can not have mixed types of weights. The show interface command can be used to display the available bandwidth.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Available Bandwidth Available bandwidth is calculated according to the following formula:

© 2006 Cisco Systems, Inc. All rights reserved.ONT v CBWFQ Benefits and Drawbacks BenefitsCustom-defined classifications Minimum bandwidth allocation Finer granularity and scalability DrawbackVoice traffic can still suffer unacceptable delay.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Configuring and Monitoring CBWFQ

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Configuring CBWFQ bandwidth router(config-pmap-c)# Allocates a fixed amount of bandwidth to a class. Sets the value in kilobits per second. bandwidth percent percent router(config-pmap-c)# Allocates a percentage of bandwidth to a class. The configured (or default) interface bandwidth is used to calculate the guaranteed bandwidth. bandwidth remaining percent percent router(config-pmap-c)# Allocates a percentage of available bandwidth to a class.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Configuring CBWFQ (Cont.) queue-limit router(config-pmap-c)# Sets the maximum number of packets that this queue can hold. The default maximum is 64. fair-queue [number-of-dynamic-queues] router(config-pmap-c)# The class-default class can be configured to use WFQ. The number of dynamic queues is a power of 2 in the range from 16 to 4096, specifying the number of dynamic queues.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Example of CBWFQ Router(config)#access-list 101 permit udp host host range Router(config-if)#access-list 102 permit udp host host range Router(config)#class-map class1 Router(config-cmap)#match access-group 101 Router(config-cmap)#exit Router(config)#class-map class2 Router(config-cmap)#match access-group 102 Router(config-cmap)#exit Router(config)#policy-map policy1 Router(config-pmap)#class class1 Router(config-pmap-c)#bandwidth 3000 Router(config-pmap-c)#queue-limit 30 Router(config-pmap-c)#exit Router(config-pmap)#class class2 Router(config-pmap-c)#bandwidth 2000 Router(config-pmap-c)#exit Router(config-pmap)#class class-default Router(config-pmap-c)#fair-queue Router(config-pmap-c)#exit

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Monitoring CBWFQ show policy-map interface [interface] router> Displays parameters and statistics of CBWFQ Router#show policy-map interface FastEthernet0/0 Service-policy output: policy1 Class-map: class1 (match-all) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match: access-group 101 Queueing Output Queue: Conversation 265 Bandwidth 3000 (kbps) Max Threshold 30 (packets) (pkts matched/bytes matched) 0/0 (depth/total drops/no-buffer drops) 0/0/0 Class-map: class-default (match-any) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match: any Queueing Flow Based Fair Queueing

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Low Latency Queuing

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Low Latency Queuing A priority queue is added to CBWFQ for real-time traffic. High-priority classes are guaranteed: –Low-latency propagation of packets –Bandwidth High-priority classes are also policed when congestion occursthey then cannot exceed their guaranteed bandwidth. Lower-priority classes use CBWFQ.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v LLQ Architecture and Benefits

© 2006 Cisco Systems, Inc. All rights reserved.ONT v LLQ Architecture

© 2006 Cisco Systems, Inc. All rights reserved.ONT v LLQ Benefits High-priority classes are guaranteed: –Low-latency propagation of packets –Bandwidth Configuration and operation are consistent across all media types. Entrance criteria to a class can be defined by an ACL. –Not limited to UDP ports as with IP RTP priority –Defines trust boundary to ensure simple classification and entry to a queue

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Configuring and Monitoring LLQ

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Configuring LLQ priority bandwidth [burst] router(config-pmap-c)# Allocates a fixed amount of bandwidth (in kilobits per second) to a class and ensures expedited forwarding. Traffic exceeding the specified bandwidth is dropped if congestion exists; otherwise, policing is not used. priority percent percentage [burst] router(config-pmap-c)# Allocates a percentage of configured or default interface bandwidth to a class and ensures expedited forwarding. Traffic exceeding the specified bandwidth is dropped if congestion exists.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Configuring LLQ (Cont.) class-map voip match ip precedence 5 ! class-map mission-critical match ip precedence 3 4 ! class-map transactional match ip precedence 1 2 ! policy-map Policy1 class voip priority percent 10 class mission-critical bandwidth percent 30 class transactional bandwidth percent 20 class class-default fair-queue

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Monitoring LLQ show policy-map interface interface router> Displays the packet statistics of all classes that are configured for all service policies on the specified interface or subinterface router>show policy-map interface fastethernet 0/0 FastEthernet0/0 Service-policy output: LLQ Class-map: LLQ (match-any) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match: any Weighted Fair Queueing Strict Priority Output Queue: Conversation 264 Bandwidth 1000 (kbps) Burst (Bytes) (pkts matched/bytes matched) 0/0 (total drops/bytes drops) 0/0 Class-map: class-default (match-any) 0 packets, 0 bytes 5 minute offered rate 0 bps, drop rate 0 bps Match: any

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Summary Basic queuing mechanisms can be used to build more advanced queuing mechanisms such as CBWFQ and LLQ. CBWFQ is a mechanism that is used to overcome the deficiencies of WFQ. CBWFQ extends the standard WFQ functionality to provide support for traffic classes. Classes are based on user- defined match criteria. CBWFQ provides a minimum bandwidth guarantee according to traffic classes.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v Summary (Cont.) LLQ is implemented within CBWFQ by the addition of a priority queue that is serviced using a strict-priority scheduler for time-sensitive traffic such as voice and video. The LLQ scheduler guarantees both low latency and bandwidth for the traffic in the priority queue. In the event of congestion, if the priority-queue traffic exceeds the bandwidth guarantee, a congestion-aware policer is used to drop the exceeds traffic.

© 2006 Cisco Systems, Inc. All rights reserved.ONT v