Table of Contents 1 QoS Overview QoS Policy Configuration Priority Mapping Configuration 3-1

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1 Table of Contents 1 QoS Overview 1-1 Introduction to QoS 1-1 Networks Without QoS Guarantee 1-1 QoS Requirements of New Applications 1-1 Congestion: Causes, Impacts, and Countermeasures 1-2 Causes 1-2 Impacts 1-2 Countermeasures 1-2 QoS Technology Implementations 1-3 End-to-End QoS 1-3 Traffic Classification 1-3 Packet Precedences QoS Policy Configuration 2-1 QoS Policy Overview 2-1 Configuring a QoS Policy 2-2 Defining a Class 2-2 Defining a Traffic Behavior 2-3 Defining a Policy 2-5 Applying the QoS Policy 2-7 Applying the QoS Policy to an Interface 2-8 Applying the QoS Policy to a VLAN 2-9 Applying the QoS Policy Globally 2-9 Displaying and Maintaining QoS Policies Priority Mapping Configuration 3-1 Priority Mapping Overview 3-1 Introduction to Priority Mapping 3-1 Concepts 3-1 Introduction to Priority Mapping Tables 3-2 Configuring a Priority Mapping Table 3-3 Configuration Prerequisites 3-3 Configuration Procedure 3-3 Configuration Example 3-3 Configuring the 802.1P Priority of a Port 3-4 Configuration Prerequisites 3-4 Configuration Procedure 3-4 Configuration Example 3-5 Configuring the Trusted Precedence Type for a Port 3-5 Configuration Prerequisites 3-5 Configuration Procedure 3-5 Configuration Example 3-5 Displaying and Maintaining Priority Mapping 3-6 i

2 4 Traffic Policing and Traffic Shaping Configuration 4-1 Traffic Policing and Traffic Shaping Overview 4-1 Traffic Evaluation and Token Bucket 4-1 Traffic Policing 4-2 Traffic Shaping 4-3 Traffic Policing, GTS and Line Rate Configuration 4-4 Configuring Traffic Policing 4-4 Configuring GTS 4-5 Displaying and Maintaining Traffic Policing, GTS and Line Rate Aggregation CAR Configuration 5-1 Aggregation CAR Overview 5-1 Configuring an Aggregation CAR Policy 5-1 Configuration Prerequisites 5-1 Configuration Procedure 5-2 Configuration Example 5-2 Referencing Aggregation CAR in a Traffic Behavior 5-2 Configuration Prerequisites 5-2 Configuration Procedure 5-3 Configuration Example 5-3 Displaying and Maintaining Aggregation CAR Congestion Management Configuration 6-1 Overview 6-1 Congestion Management Policies 6-1 Configuring SP Queuing 6-3 Configuration procedure 6-3 Configuration example 6-3 Configuring WRR Queuing 6-4 Configuration procedure 6-4 Configuration example 6-4 Configuring SP+WRR Queuing 6-5 Configuration Procedure 6-5 Configuration Example 6-5 Displaying Congestion Management Congestion Avoidance 7-1 Congestion Avoidance Overview 7-1 Configuring WRED 7-2 Configuration Procedure 7-2 Configuration Example 7-3 Configuring Queue Length 7-3 Configuration Prerequisites 7-3 Configuration Procedure 7-3 Configuration Example 7-3 Displaying and Maintaining WRED Traffic Mirroring Configuration 8-1 Traffic Mirroring Overview 8-1 Configuring Traffic Mirroring 8-1 ii

3 Mirroring Traffic to an Interface 8-2 Mirroring Traffic to the CPU 8-2 Displaying and Maintaining Traffic Mirroring 8-2 Traffic Mirroring Configuration Examples 8-3 Example for Mirroring Traffic to an Interface Burst Configuration 9-1 Overview 9-1 Configuring Burst 9-1 Burst Configuration Example 9-1 Network Requirements 9-1 Configuration Procedure 9-2 iii

4 1 QoS Overview This chapter covers the following topics: Introduction to QoS Networks Without QoS Guarantee QoS Requirements of New Applications Congestion: Causes, Impacts, and Countermeasures QoS Technology Implementations Introduction to QoS Quality of Service (QoS) reflects the ability of a network to meet customer needs. In an internet, QoS evaluates the ability of the network to forward packets of different services. The evaluation can be based on different criteria because the network may provide various services. Generally, QoS performance is measured with respect to bandwidth, delay, jitter, and packet loss ratio during packet forwarding process. Networks Without QoS Guarantee On traditional IP networks without QoS guarantee, devices treat all packets equally and handle them using the first in first out (FIFO) policy. All packets share the resources of the network and devices. How many resources the packets can obtain completely depends on the time they arrive. This service is called best-effort. It delivers packets to their destinations as possibly as it can, without any guarantee for delay, jitter, packet loss ratio, and so on. This service policy is only suitable for applications insensitive to bandwidth and delay, such as Word Wide Web (WWW) and . QoS Requirements of New Applications The Internet has been growing along with the fast development of networking technologies. Besides traditional applications such as WWW, and FTP, network users are experiencing new services, such as tele-education, telemedicine, video telephone, videoconference and Video-on-Demand (VoD). Enterprise users expect to connect their regional branches together with VPN technologies to carry out operational applications, for instance, to access the database of the company or to monitor remote devices through Telnet. These new applications have one thing in common, that is, they all have special requirements for bandwidth, delay, and jitter. For example, videoconference and VoD require high bandwidth, low delay and jitter. As for mission-critical applications, such as transactions and Telnet, they may not require high bandwidth but do require low delay and preferential service during congestion. The emerging applications demand higher service performance of IP networks. Better network services during packets forwarding are required, such as providing dedicated bandwidth, reducing packet loss ratio, managing and avoiding congestion, and regulating network traffic. To meet these requirements, networks must provide more improved services. 1-1

5 Congestion: Causes, Impacts, and Countermeasures Network congestion is a major factor contributed to service quality degrading on a traditional network. Congestion is a situation where the forwarding rate decreases due to insufficient resources, resulting in extra delay. Causes Congestion easily occurs in complex packet switching circumstances in the Internet. The following figure shows two common cases: Figure 1-1 Traffic congestion causes 100M 100M 10M 10M 100M 100M>10M 50M (100M+10M+50M)>100M (1) (2) The traffic enters a device from a high speed link and is forwarded over a low speed link. The packet flows enter a device from several incoming interfaces and are forwarded out an outgoing interface, whose rate is smaller than the total rate of these incoming interfaces. When traffic arrives at the line speed, a bottleneck is created at the outgoing interface causing congestion. Besides bandwidth bottlenecks, congestion can be caused by resource shortage in various forms such as insufficient processor time, buffer, and memory, and by network resource exhaustion resulting from excessive arriving traffic in certain periods. Impacts Congestion may bring these negative results: Increased delay and jitter during packet transmission Decreased network throughput and resource use efficiency Network resource (memory in particular) exhaustion and even system breakdown It is obvious that congestion hinders resource assignment for traffic and thus degrades service performance. Congestion is unavoidable in switched networks and multi-user application environments. To improve the service performance of your network, you must address the congestion issues. Countermeasures A simple solution for congestion is to increase network bandwidth, however, it cannot solve all the problems that cause congestion because you cannot increase network bandwidth infinitely. A more effective solution is to provide differentiated services for different applications through traffic control and resource allocation. In this way, resources can be used more properly. During resources allocation and traffic control, the direct or indirect factors that might cause network congestion should be controlled to reduce the probability of congestion. Once congestion occurs, resource allocation should 1-2

6 be performed according to the characteristics and demands of applications to minimize the effects of congestion. QoS Technology Implementations End-to-End QoS Figure 1-2 End-to-end QoS model As shown in Figure 1-2, traffic classification, traffic policing, traffic shaping, congestion management, and congestion avoidance are the foundations for a network to provide differentiated services. Mainly they implement the following functions: Traffic classification uses certain match criteria to organize packets with different characteristics into different classes. Traffic classification is usually applied in the inbound direction of a port. Traffic policing polices particular flows entering or leaving a device according to configured specifications and can be applied in both inbound and outbound directions of a port. When a flow exceeds the specification, some restriction or punishment measures can be taken to prevent overconsumption of network resources. Traffic shaping proactively adjusts the output rate of traffic to adapt traffic to the network resources of the downstream device and avoid unnecessary packet drop and congestion. Traffic shaping is usually applied in the outbound direction of a port. Congestion management provides a resource scheduling policy to arrange the forwarding sequence of packets when congestion occurs. Congestion management is usually applied in the outbound direction of a port. Congestion avoidance monitors the usage status of network resources and is usually applied in the outbound direction of a port. As congestion becomes worse, it actively reduces the amount of traffic by dropping packets. Among these QoS technologies, traffic classification is the basis for providing differentiated services. Traffic policing, traffic shaping, congestion management, and congestion avoidance manage network traffic and resources in different ways to realize differentiated services. This section is focused on traffic classification, and the subsequent sections will introduce the other technologies in details. Traffic Classification When defining match criteria for classifying traffic, you can use IP precedence bits in the type of service (ToS) field of the IP packet header, or other header information such as IP addresses, MAC addresses, 1-3

7 IP protocol field and port numbers. You can define a class for packets with the same quintuple (source address, source port number, protocol number, destination address and destination port number for example), or for all packets to a certain network segment. When packets are classified on the network boundary, the precedence bits in the ToS field of the IP packet header are generally re-set. In this way, IP precedence can be directly adopted to classify the packets in the network. IP precedence can also be used in queuing to prioritize traffic. The downstream network can either adopt the classification results from its upstream network or classify the packets again according to its own criteria. To provide differentiated services, traffic classes must be associated with certain traffic control actions or resource allocation actions. What traffic control actions to use depends on the current phase and the resources of the network. For example, CAR is used to police packets when they enter the network; GTS is performed on packets when they flow out of the node; queue scheduling is performed when congestion happens; congestion avoidance measures are taken when the congestion deteriorates. Packet Precedences This section introduces IP precedence, ToS precedence, differentiated services codepoint (DSCP) values, and 802.1p priority. 1) IP precedence, ToS precedence, and DSCP values Figure 1-3 DS field and ToS bytes As shown in Figure 1-3, the ToS field of the IP header contains eight bits: the first three bits (0 to 2) represent IP precedence from 0 to 7; the subsequent four bits (3 to 6) represent a ToS value from 0 to 15. According to RFC 2474, the ToS field of the IP header is redefined as the differentiated services (DS) field, where a DSCP value is represented by the first six bits (0 to 5) and is in the range 0 to 63. The remaining two bits (6 and 7) are reserved. Table 1-1 Description on IP Precedence IP Precedence (decimal) IP Precedence (binary) Description Routine priority immediate flash flash-override critical internet 1-4

8 IP Precedence (decimal) IP Precedence (binary) Description network In a network in the Diff-Serve model, traffic is grouped into the following four classes, and packets are processed according to their DSCP values. Expedited Forwarding (EF) class: In this class, packets are forwarded regardless of link share of other traffic. The class is suitable for preferential services requiring low delay, low packet loss, low jitter, and high bandwidth. Assured forwarding (AF) class: This class is divided into four subclasses (AF 1 to AF 4), each containing three drop priorities for more granular classification. The QoS level of the AF class is lower than that of the EF class. Class selector (CS) class: This class is derived from the IP ToS field and includes eight subclasses; Best effort (BE) class: This class is a special CS class that does not provide any assurance. AF traffic exceeding the limit is degraded to the BE class. Currently, all IP network traffic belongs to this class by default. Table 1-2 Description on DSCP values DSCP value (decimal) DSCP value (binary) Description ef af af af af af af af af af af af af cs cs cs cs cs cs cs be (default) 1-5

9 2) 802.1p priority 802.1p priority lies in Layer 2 packet headers and is applicable to occasions where Layer 3 header analysis is not needed and QoS must be assured at Layer 2. Figure 1-4 An Ethernet frame with an 802.1Q tag header As shown in Figure 1-4, the 4-byte 802.1Q tag header consists of the tag protocol identifier (TPID, two bytes in length), whose value is 0x8100, and the tag control information (TCI, two bytes in length). Figure 1-5 presents the format of the 802.1Q tag header. Figure Q tag header Byte 1 Byte 2 Byte 3 Byte 4 TPID (Tag protocol identifier) TCI (Tag control information) CFI Priority VLAN ID The priority in the 802.1Q tag header is called 802.1p priority, because its use is defined in IEEE 802.1p. Table 1-3 presents the values for 802.1p priority. Table 1-3 Description on 802.1p priority 802.1p priority (decimal) 802.1p priority (binary) Description best-effort background spare excellent-effort controlled-load video voice network-management 1-6

10 2 QoS Policy Configuration Interfaces mentioned in this section represent Layer 2 Ethernet ports and Layer 3 Ethernet interfaces. Layer 3 Ethernet interfaces refer to Ethernet ports configured to operate in route mode. For how to switch the operating mode of an Ethernet port, refer to Ethernet Interface Configuration in the Access Volume. When configuring a QoS policy, go to these sections for information you are interested in: QoS Policy Overview Configuring a QoS Policy Applying the QoS Policy Displaying and Maintaining QoS Policies QoS Policy Overview A QoS policy involves three components: class, traffic behavior, and policy. You can associate a class with a traffic behavior using a QoS policy. Class Classes are used to identify traffic. A class is identified by a class name and contains some match criteria. You can define a set of match criteria to classify packets, and the relationship between criteria can be and or or. and: The device considers a packet belongs to a class only when the packet matches all the criteria in the class. or: The device considers a packet belongs to a class as long as the packet matches one of the criteria in the class. Traffic behavior A traffic behavior defines a set of QoS actions for packets. Policy A policy associates a class with a traffic behavior. You can configure multiple class-to-traffic behavior associations in a policy. 2-1

11 Configuring a QoS Policy Follow these steps to configure a QoS policy: 1) Create a class and define a set of match criteria in class view. 2) Create a traffic behavior and define a set of QoS actions in traffic behavior view. 3) Create a policy and associate the traffic behavior with the class in policy view. Defining a Class To define a class, you need to specify a name for it and then configure match criteria in class view. Follow these steps to define a class: Enter system view system-view Create a class and enter class view traffic classifier tcl-name [ operator { and or } ] By default, the relation between match criteria is and. Define a match criterion if-match match-criteria match-criteria: Matching clauses to be defined for a class. Table 2-1 describes the available keyword and argument combinations for this argument. Table 2-1 The keyword and argument combinations for the match-criteria argument Keyword and argument combination acl { access-list-number name acl-name } acl ipv6 { access-list-number name acl-name } any customer-dot1p 8021p-list customer-vlan-id vlan-id-list Description Matches an IPv4 ACL specified by its number or name. The access-list-number argument specifies an ACL by its number, which ranges from 2000 to 4999; the name acl-name keyword-argument combination specifies an ACL by its name. Note that a packet is regarded matching the ACL if it matches a rule in the ACL, regardless of whether the operator configured in the class is and or or. Matches an IPv6 ACL specified by its number or name. The access-list-number argument specifies an ACL by its number, which ranges from 2000 to 3999; the name acl-name keyword-argument combination specifies an ACL by its name. Note that a packet is regarded matching the ACL if it matches a rule in the ACL, regardless of whether the operator configured in the class is and or or. Matches all packets. Matches packets by 802.1p precedence of customer network. The 8021p-list argument is a list of CoS values, in the range of 0 to 7. Matches the packets of specified VLANs of user networks. The vlan-id-list argument specifies a list of VLAN IDs, in the form of vlan-id to vlan-id or multiple discontinuous VLAN IDs (separated by space). You can specify up to eight VLAN IDs for this argument at a time. VLAN ID is in the range 1 to

12 Keyword and argument combination destination-mac mac-address dscp dscp-list ip-precedence ip-precedence-list protocol protocol-name service-dot1p 8021p-list service-vlan-id vlan-id-list source-mac mac-address Description Matches the packets with a specified destination MAC address. Matches packets by DSCP precedence. The dscp-list argument is a list of DSCP values. You can provide up to eight space-separated DSCP values for this argument. DSCP is in the range of 0 to 63. Matches packets by IP precedence. The ip-precedence-list argument is a list of IP precedence values. You can provide up to eight space-separated IP precedence values for this argument. IP precedence is in the range 0 to 7. Matches the packets of a specified protocol. The protocol-name argument can be IP, IPv6. Matches packets by 802.1p precedence of the service provider network. The 8021p-list argument is a list of CoS values in the range of 0 to 7. Matches the packets of the VLANs of the operator s network. The vlan-id-list argument is a list of VLAN IDs, in the form of vlan-id to vlan-id or multiple discontinuous VLAN IDs (separated by space). You can specify up to eight VLAN IDs for this argument at a time. VLAN ID is in the range of 1 to Matches the packets with the specified source MAC address. Configuration example 1) Network requirements Configure a class named test to match the packets with their IP precedence being 6. 2) Configuration procedure # Enter system view. <Sysname> system-view # Create the class and enter the class view. [Sysname] traffic classifier test # Define the classification rule. [Sysname-classifier-test] if-match ip-precedence 6 Defining a Traffic Behavior A traffic behavior is a set of QoS actions. To define a traffic behavior, you must first create it and then configure actions for the behavior as required in traffic behavior view. If you want to define a primap behavior, you need to define a priority mapping table as required. Refer to Priority Mapping Configuration for more information. Follow these steps to define a traffic behavior: Enter system view system-view 2-3

13 Create a traffic behavior and enter traffic behavior view traffic behavior behavior-name Enable traffic accounting accounting Optional Configure a CAR policy Reference an aggregation CAR policy car cir committed-information-rate [ cbs committed-burst-size [ ebs excess-burst-size ] ] [ pir peak-information-rate ] [ red action ] car name car-name Optional For detailed information about CAR, refer to Traffic Policing and Traffic Shaping Configuration. Optional For detailed information about aggregation CAR, refer to Aggregation CAR Configuration. Drop or send packets filter { deny permit } Configure a GTS policy gts cir committed-information-rate [ cbs committed-burst-size [ ebs excess-burst-size [ queue-length queue-length ] ] ] [ pir peak-information-rate ] Optional deny Dropping packets. permit Permitting packets to pass through. Optional For detailed information about GTS, refer to Traffic Policing and Traffic Shaping Configuration. Mirror packets to the CPU or an interface mirror-to { cpu interface interface-type interface-number } Optional For detailed information about traffic mirroring, refer to Traffic Mirroring Configuration. Insert a VLAN tag nest top-most vlan-id vlan-id Optional Perform priority mapping with the specified priority mapping table to obtain a set of QoS priority values for the interesting packets Redirect traffic to a specified target primap pre-defined { dscp-lp dscp-dp dscp-dot1p dscp-dscp } redirect { cpu interface interface-type interface-number next-hop { ipv4-add [ ipv4-add ] ipv6-add [ interface-type interface-number ] [ ipv6-add [ interface-type interface-number ] ] } } Optional Optional Set the DSCP value for packets remark dscp dscp-value Optional Set the 802.1p priority for packets Set the drop precedence for packets Set the IP precedence for packets remark dot1p 8021p remark drop-precedence drop-precedence-value remark ip-precedence ip-precedence-value Optional Optional Optional 2-4

14 Set the local precedence for packets Set the provider network VLAN ID for packets Display traffic behavior configuration information remark local-precedence local-precedence remark service-vlan-id vlan-id-value display traffic behavior { system-defined user-defined } [ behavior-name ] Optional Optional Optional Available in any view Some actions are conflicting. Avoid configuring them in the same traffic behavior, because doing so can prevent the policy referencing the behavior from being successfully applied. The accounting command is conflicting with the aggregation CAR action. The filter deny command is conflicting with all other actions. The primap command is conflicting with all remark commands but the remark dscp command. The redirect next-hop command is conflicting with the remark service-vlan-id command and the nest command. The remark service-vlan-id command is conflicting with the nest command. Configuration example 1) Network requirements Create a traffic behavior named test, configuring TP action for it, with the CAR being 100 kbps. 2) Configuration procedure # Enter system view. <Sysname> system-view # Create the traffic behavior (This operation leads you to traffic behavior view). [Sysname] traffic behavior test # Configure TP action for the traffic behavior. [Sysname-behavior-test] car cir 100 Defining a Policy Configuration procedure A policy is a set of associations between classes and traffic behaviors. These associations are executed in the order they are configured. QoS can collaborate with some other functions to limit the effective scope of a class-behavior association. These collaborative functions include VLAN mapping, IP source guard, and voice VLAN. With VLAN mapping, the class-behavior association applies only for VLAN mapping. 2-5

15 With IP source guard, the class-behavior association applies to only the packets passing the check of the IP source guard module. For information about IP source guard, refer to IP Source Guard Configuration in the Security Volume. With voice VLAN, the class-behavior association applies to only the packets recognized as voice packets by the switch. A switch considers a packet as a voice packet if its source MAC address matches the OUI list maintained by the switch for identifying voice traffic. For information about OUI addresses, refer to VLAN Configuration in the Access Volume. To collaborate with the IP source guard or voice VLAN module, a class-behavior association must be configured with the if-match any clause as its classifier for matching any packets. To reduce your configuration efforts, the multi-service cooperation QoS mode is provided. This mode is a global configuration. After it is enabled, All class-behavior associations configured with the if-match any clause as the only traffic classifier apply to only the packets passing the check of the IP source guard function. All class-behavior associations configured with the if-match source-mac oui-mac (oui-mac is a MAC address matching the OUI list of the device) clause as the only traffic classifier collaborates with the voice VLAN feature, that is, the class-behavior association applies to all packets whose source MAC addresses are in the OUI list of the switch. Multi-service cooperation QoS mode takes effect on all QoS policies applied to ports. If neither a collaborative function nor the multi-service cooperation QoS mode is specified, a QoS policy applies to all packets. Follow these steps to associate a class with a behavior in a QoS policy: To do Use the command Remarks Enter system view system-view Enable the multi-service cooperation QoS mode globally Create a policy and enter the policy view Associate a traffic behavior with a class policy mode multi-service-cooperation qos policy policy-name classifier tcl-name behavior behavior-name [ mode { do1q-tag-manipulation ip-source-guard voice-vlan } ] Optional This mode applies to only the QoS policies configured after it is enabled. If needed, you can specify a collaborative module to limit the effective scope of the class-behavior association. If you have enabled the multi-service cooperation QoS mode, you are recommended not to specify the ip-source-guard or voice-vlan keyword. 2-6

16 To do Use the command Remarks Display the configuration of the specified class in the specified policy and the behavior associated with the class display qos policy user-defined [ policy-name [ classifier tcl-name ] ] Optional Available in any view Configuration example Configure IP source guard on port Ethernet 1/0/1, enabling its dynamic binding function (which collaborates with DHCP snooping to obtain IP-MAC address entries) and creating a static binding for IP address and MAC address Enable the IP source guard to collaborate with a QoS policy to limit the rate of the traffic originated from any of its IP-MAC address binding entry to 10 Mbps. # Create a CAR policy to limit the traffic rate to 10 Mbps. When associating a behavior with a class in the policy, configure the class-behavior association to apply to only the IP source guard function. <Sysname> system-view [Sysname] traffic classifier cl [Sysname-classifier-c1] if-match any [Sysname-classifier-c1] quit [Sysname] traffic behavior be [Sysname-behavior-be] car cir [Sysname-behavior-be] quit [Sysname] qos policy ipcheck [Sysname-qospolicy-ipcheck] classifier cl behavior be mode ip-source-guard [Sysname-qospolicy-ipcheck] quit # Apply the policy to the inbound direction of Ethernet 1/0/1. [Sysname]interface Ethernet 1/0/1 [Sysname-Ethernet1/0/1]qos apply policy ipcheck inbound # Configure the dynamic binding function of IP source guard and enable DHCP snooping on Ethernet 1/0/1. [Sysname-Ethernet1/0/1] ip check source ip-address mac-address [Sysname-Ethernet1/0/1]quit [Sysname] dhcp-snooping # Bind IP address and MAC address with Ethernet 1/0/1. [Sysname-Ethernet1/0/1] user-bind ip-address mac-address Applying the QoS Policy You can apply the QoS policy to different occasions: Applied to an interface, the policy takes effect on the traffic sent or received on the interface; Applied to a VLAN, the policy takes effect on the traffic sent or received on all ports in the VLAN; Applied globally, the policy takes effect on the traffic sent or received on all ports. 2-7

17 You can modify the classification rules, traffic behaviors, and classifier-behavior associations of a QoS policy already applied. Applying the QoS Policy to an Interface A policy can be applied to multiple interfaces. Only one policy can be applied in one direction of an interface. Currently, the S3610 and S5510 series switches support QoS policies only in the inbound direction. Configuration procedure Follow these steps to apply the QoS policy to an interface: Enter system view system-view Enter interface view or port group view Enter interface view Enter port group view interface interface-type interface-number port-group manual port-group-name Use either command Settings in interface view take effect on the current interface; settings in port group view take effect on all ports in the port group. Apply the policy to the interface/port group qos apply policy policy-name inbound Configuration example 1) Network requirements Configure a policy named test to associate the traffic behavior named test_behavior with the class named test_class. Apply the policy to the inbound direction of Ethernet 1/0/1 port. 2) Configuration procedure # Enter system view. <Sysname> system-view # Create a policy and enter the policy view. [Sysname]qos policy test [Sysname-qospolicy-test] # Associate the traffic behavior named test_behavior with the class named test_class. [Sysname-qospolicy-test] classifier test_class behavior test_behavior [Sysname-qospolicy-test] quit # Enter port view. [Sysname] interface Ethernet 1/0/1 [Sysname-Ethernet1/0/1] # Apply the policy to the port. 2-8

18 [Sysname-Ethernet1/0/1] qos apply policy test inbound Applying the QoS Policy to a VLAN You can apply a QoS policy to a VLAN to regulate traffic of the VLAN. Configuration procedure Follow these steps to apply the QoS policy to a VLAN: Enter system view system-view Apply the QoS policy to the specified VLAN(s) qos vlan-policy policy-name vlan vlan-id-list inbound QoS policies cannot be applied to dynamic VLANs, for example, VLANs created by GVRP. On an S5510 series switch, if the QoS policy containing a traffic policing action is applied to a VLAN containing any of the first 12 ports and any of the last 16 ports at the same time, traffic twice the defined traffic limit may pass. Configuration example # Apply QoS policy test_policy to the inbound direction of VLAN 200, VLAN 300, VLAN 400, and VLAN 500. <Sysname> system-view [Sysname] qos vlan-policy test_policy vlan inbound Applying the QoS Policy Globally You can apply the QoS policy globally to the inbound direction of all ports. Configuration procedure Follow these steps to apply a QoS policy globally: Enter system view system-view Apply a QoS policy globally qos apply policy policy-name global inbound Configuration example # Apply QoS policy test_policy to the inbound direction globally. <Sysname> system-view [Sysname] qos apply policy test_policy global inbound 2-9

19 Displaying and Maintaining QoS Policies Display traffic class information Display traffic behavior configuration information Display system-defined or user-defined QoS policy configuration information Display QoS policy configuration on the specified or all interfaces Display VLAN QoS policy information Display information of global QoS policies Clear VLAN QoS policy statistics Clear statistics of a global QoS policy display traffic classifier user-defined [ tcl-name ] display traffic behavior user-defined [ behavior-name ] display qos policy user-defined [ policy-name [ classifier tcl-name ] ] display qos policy interface [ interface-type interface-number ] [ inbound ] display qos vlan-policy { name policy-name vlan vlan-id } display qos policy global inbound reset qos vlan-policy [ vlan vlan-id ] reset qos policy global { inbound outbound } Available in any view Available in any view Available in any view Available in any view Available in any view Available in any view Available in user view Available in user view 2-10

20 3 Priority Mapping Configuration Interfaces mentioned in this section represent Layer 2 Ethernet ports and Layer 3 Ethernet interfaces. Layer 3 Ethernet interfaces refer to Ethernet ports configured to operate in route mode. For how to switch the operating mode of an Ethernet port, refer to Ethernet Interface Configuration in the Access Volume. When configuring priority mapping, go to these sections for information you are interested in: Priority Mapping Overview Configuring a Priority Mapping Table Configuring the 802.1P Priority of a Port Configuring the Trusted Precedence Type for a Port Displaying and Maintaining Priority Mapping Priority Mapping Overview Introduction to Priority Mapping When a packet enters a network, it will be marked with a certain value, which indicates the scheduling weight or forwarding priority of the packet. Then, the intermediate nodes in the network process the packet according to the priority. When a packet enters a device, the device assigns to the packet a set of predefined parameters (including the 802.1p priority, DSCP values, IP precedence, local precedence, and drop precedence). Concepts For more information about 802.1p priority, DSCP values, and IP precedence, refer to Packet Precedences. The local precedence and drop precedence are described as follows. Local precedence is the precedence that the switch assigns to a packet and it corresponds to the number of an output queue on the port. Local precedence takes effect only on the local switch. Drop precedence is a parameter that is referred to when dropping packets. The higher the drop precedence, the more likely a packet is dropped. For packets without 802.1q tags, the switch uses the priority of the receiving port as the 802.1p precedence of the received packets, and then obtains the local precedence of the received packets by mapping the 802.1p precedence. For packets with 802.1q tags, the switch provides the following two priority trust modes: 3-1

21 Trusting packet priority The switch looks up the 802.1p-to-local and 802.1p-to-drop priority mapping tables based on the 802.1p priority of received packets for the local precedence and drop precedence to be assigned to the received packets. Trusting port priority The switch looks up the 802.1p-to-local and 802.1p-to-drop priority mapping tables based on the 802.1p priority of the receiving port instead of that carried in the received packets for the local precedence and drop precedence to be assigned to the received packets. Introduction to Priority Mapping Tables The device provides various types of priority mapping table, as listed below. dot1p-dp: 802.1p-to-drop priority mapping table. dot1p-lp: 802.1p-to-local priority mapping table. dscp-dot1p: DSCP-to-802.1p priority mapping table, which is applicable to only IP packets. dscp-dp: DSCP-to-drop priority mapping table, which is applicable to only IP packets. dscp-dscp: DSCP-to-DSCP priority mapping table, which is applicable to only IP packets. dscp-lp: DSCP-to-local priority mapping table, which is applicable to only IP packets. Table 3-1 and Table 3-2 list the default priority mapping tables. Table 3-1 The default dot1p-lp and dot1p-dp mappings Input priority value dot1p-lp mapping dot1p-dp mapping 802.1p priority (dot1p) Local precedence (lp) Drop precedence (dp) Table 3-2 The default dscp-lp, dscp-dp, and dscp-dot1p mappings Input priority value dscp-lp mapping dscp-dp mapping dscp-dot1p mapping dscp Local precedence (lp) Drop precedence (dp) 802.1p priority (dot1p) 0 to to to to to to

22 Input priority value dscp-lp mapping dscp-dp mapping dscp-dot1p mapping 48 to to For the default dscp-dscp mappings, an input value yields a target value that is equal to it. Configuring a Priority Mapping Table You can modify the priority mapping tables of a device as needed. Configuration Prerequisites You need to decide on the new mapping values. Configuration Procedure Follow these steps to configure a priority mapping table: Enter system view system-view Enter priority mapping table view Configure the priority mapping table qos map-table { dot1p-lp dot1p-dp dscp-lp dscp-dp dscp-dot1p dscp-dscp } import import-value-list export export-value You can enter the corresponding priority mapping table view as required. Newly configured mappings overwrite the previous ones. Configuration Example Network requirements Configure a dot1p-lp priority mapping table as shown below. Table 3-3 dot1p-lp mappings 802.1p priority Local precedence

23 802.1p priority Local precedence Configuration procedure # Enter system view. <Sysname> system-view # Enter the inbound dot1p-lp priority mapping table view. [Sysname] qos map-table dot1p-lp # Modify dot1p-lp priority mapping parameters. [Sysname-maptbl-dot1p-lp] import 0 1 export 0 [Sysname-maptbl-dot1p-lp] import 2 3 export 1 [Sysname-maptbl-dot1p-lp] import 4 5 export 2 [Sysname-maptbl-dot1p-lp] import 6 7 export 3 Configuring the 802.1P Priority of a Port By default, the switch uses the priority of the receiving port as the 802.1p priority of the received packets, and based on it looks up the 802.1p-to-local priority mapping table for local precedence, and assigns the local precedence to the received packets. The packets are then put into output queues by their local precedence. Port priority is in the range 0 to 7. You can tune the 802.1p priority of a port as needed. Configuration Prerequisites You need to decide on a priority for the port. Configuration Procedure Follow these steps to configure port priority: Enter system view system-view Enter interface view or port group view Enter interface view Enter port group view interface interface-type interface-number port-group manual port-group-name Use either command Settings in interface view take effect on the current interface; settings in port group view take effect on all ports in the port group. Configure a priority for the port qos priority priority-value The default port priority is

24 Configuration Example Network requirements Set the port priority of port Ethernet 1/0/1 to 7. Configuration procedure # Enter system view. <Sysname> system-view # Set the priority of Ethernet 1/0/1 to 7. [Sysname] interface ethernet 1/0/1 [Sysname-Ethernet1/0/1] qos priority 7 Configuring the Trusted Precedence Type for a Port You can configure your switch to trust the 802.1p precedence carried in received packets instead of using the priority of the receiving port as the 802.1p precedence of the received packets. Configuration Prerequisites It is determined to trust the 802.1p precedence of received packets. Configuration Procedure Follow these steps to configure the trusted precedence type: Enter system view system-view Enter interface view or port group view Enter interface view Enter port group view interface interface-type interface-number port-group manual port-group-name Use either command Settings in interface view take effect on the current interface; settings in port group view take effect on all ports in the port group.. Configure to trust the 802.1p priority carried in the received packets qos trust dot1p By default, port priority is trusted. Configuration Example Network requirements Configure port Ethernet 1/0/1 to trust the 802.1p priority of received packets. Configuration procedure # Enter system view. <Sysname> system-view # Enter port view. [Sysname] interface ethernet 1/0/1 3-5

25 # Configure port Ethernet 1/0/1 to trust the 802.1p priority of received packets. [Sysname-Ethernet1/0/1] qos trust dot1p Displaying and Maintaining Priority Mapping Display priority mapping table configuration information Display the trusted precedence type on the port display qos map-table [ dot1p-lp dot1p-dp dscp-lp dscp-dp dscp-dot1p dscp-dscp ] display qos trust interface [ interface-type interface-number ] Available in any view Available in any view 3-6

26 4 Traffic Policing and Traffic Shaping Configuration Interfaces mentioned in this section represent Layer 2 Ethernet ports and Layer 3 Ethernet interfaces. Layer 3 Ethernet interfaces refer to Ethernet ports configured to operate in route mode. For how to switch the operating mode of an Ethernet port, refer to Ethernet Interface Configuration in the Access Volume. When configuring traffic classification, traffic policing, and traffic shaping, go to these sections for information you are interested in: Traffic Policing and Traffic Shaping Overview Traffic Policing, GTS and Line Rate Configuration Displaying and Maintaining Traffic Policing, GTS and Line Rate Traffic Policing and Traffic Shaping Overview If user traffic is not limited, burst traffic will make the network more congested. Therefore it is necessary to limit user traffic in order to better utilize the network resources and provide better services for more users. For example, you can configure a flow to use only the resources committed to it in a time range, thus avoiding network congestion caused by burst traffic. Traffic policing and generic traffic shaping (GTS) limit traffic rate and resource usage according to traffic specifications. The prerequisite for traffic policing or GTS is to know whether a traffic flow has exceeded the specification. If yes, proper traffic control policies are applied. Generally, token buckets are used to evaluate traffic specifications. Traffic Evaluation and Token Bucket Token bucket features A token bucket can be considered as a container holding a certain number of tokens. The system puts tokens into the bucket at a set rate. When the token bucket is full, the extra tokens will overflow. Evaluating traffic with the token bucket The evaluation for the traffic specification is based on whether the number of tokens in the bucket can meet the need of packet forwarding. If the number of tokens in the bucket is enough to forward the packets (generally, one token is associated with a 1-bit forwarding authority), the traffic conforms to the specification, and the traffic is called conforming traffic; otherwise, the traffic does not conform to the specification, and the traffic is called excess traffic. 4-1

27 A token bucket has the following configurable parameters: Mean rate: At which tokens are put into the bucket, namely, the permitted average rate of traffic. It is usually set to the committed information rate (CIR). Burst size: the capacity of the token bucket, namely, the maximum traffic size that is permitted in each burst. It is usually set to the committed burst size (CBS). The set burst size must be greater than the maximum packet size. One evaluation is performed on each arriving packet. In each evaluation, if the number of tokens in the bucket is enough, the traffic conforms to the specification and the corresponding tokens for forwarding the packet are taken away; if the number of tokens in the bucket is not enough, it means that too many tokens have been used and the traffic is excessive. Complicated evaluation You can set two token buckets (referred to as the C bucket and E bucket respectively) in order to evaluate more complicated conditions and implement more flexible regulation policies. For example, traffic policing uses four parameters: CIR: Rate at which tokens are put into the C bucket, that is, the average packet transmission or forwarding rate allowed by the C bucket. CBS: Size of the C bucket, that is, transient burst of traffic that the C bucket can forward. Peak information rate (PIR): Rate at which tokens are put into the E bucket, that is, the average packet transmission or forwarding rate allowed by the E bucket. Excess burst size (EBS): Size of the E bucket, that is, transient burst of traffic that the E bucket can forward. Two token buckets are used in this evaluation. Their rates of putting tokens into the buckets are CIR and PIR respectively, and their sizes are CBS and EBS respectively (the two buckets are called C bucket and E bucket respectively for short), representing different permitted burst levels. In each evaluation, packets are measured against the buckets: If the C bucket has enough tokens, packets are colored green. If the C bucket does not have enough tokens but the E bucket has enough tokens, packets are colored yellow. If neither the C bucket nor the E bucket has sufficient tokens, packets are colored red. Traffic Policing The typical application of traffic policing is to supervise the specification of certain traffic entering a network and limit it within a reasonable range, or to "discipline" the extra traffic. In this way, the network resources and the interests of the carrier are protected. For example, you can limit bandwidth consumption of HTTP packets to less than 50% of the total. If the traffic of a certain session exceeds the limit, traffic policing can drop the packets or reset the IP precedence of the packets. 4-2

28 Figure 4-1 Schematic diagram for GTS Traffic policing is widely used in policing traffic entering the networks of internet service providers (ISPs). It can classify the policed traffic and perform pre-defined policing actions based on different evaluation results. These actions include: Forwarding the packets whose evaluation result is conforming. Dropping the packets whose evaluation result is excess. Traffic Shaping Traffic shaping provides measures to adjust the rate of outbound traffic actively. A typical traffic shaping application is to limit the local traffic output rate according to the downstream traffic policing parameters. The difference between traffic policing and GTS is that packets to be dropped in traffic policing are cached in a buffer or queue in GTS, as shown in Figure 4-2. When there are enough tokens in the token bucket, these cached packets are sent at an even rate. Traffic shaping may result in an additional delay while traffic policing does not. Figure 4-2 Schematic diagram for GTS Packets to be sent through this interface Tokens are put into the bucket at the set rate Packets sent Packet classification Token bucket Queue Packets dropped For example, in Figure 4-3, Switch A sends packets to Switch B. Switch B performs traffic policing on packets from Switch A and drops packets exceeding the limit. 4-3

29 Figure 4-3 GTS application You can perform traffic shaping for the packets on the outgoing interface of Switch A to avoid unnecessary packet loss. Packets exceeding the limit are cached in Switch A. Once resources are released, traffic shaping takes out the cached packets and sends them out. In this way, all the traffic sent to Switch B conforms to the traffic specification defined in Switch B. Traffic Policing, GTS and Line Rate Configuration Complete the following tasks to configure traffic policing, GTS, and line rate: Task Configuring traffic policing Configuring queue-based GTS Configuring GTS for all traffic Remarks Configure an ACL Apply CAR policies to the specified interface Configure GTS on interfaces Configure GTS on interfaces Configuring Traffic Policing Traffic policing configuration involves the following two tasks: the first task is to define the characteristics of packets to be policed; the second task is to define policing policies for the matched packets. Configuring traffic policing Follow these steps to configure ACL-based traffic policing: Enter system view system-view Configure an ACL Refer to the ACL module Enter interface view or port group view Enter interface view Enter port group view interface interface-type interface-number port-group manual port-group-name Use either command Settings in interface view take effect on the current interface; settings in port group view take effect on all ports in the port group. 4-4

30 Configure an ACL based CAR policy on the interface/port group qos car inbound acl [ ipv6 ] acl-number cir committed-information-rate [ cbs committed-burst-size [ ebs excess-burst-size ] ] [ pir peak-information-rate ] [ red action ] CBS defaults to 100,000 bytes. EBS defaults to 100,000 bytes. PIR defaults to 0. The red action keyword is discard by default. Traffic policing configuration example Configure TP on Ethernet1/0/1 to control the packets received by Ethernet1/0/1 port and matching IPv4 ACL Packets are dropped if the traffic rate exceeds 1000 kbps. # Enter system view. <Sysname> system-view # Enter port view. [Sysname] interface Ethernet 1/0/1 # Configure TP parameters. [Sysname-Ethernet1/0/1] qos car inbound acl 2000 cir 1000 red discard Configuring GTS Traffic shaping configuration involves: Queue-based GTS: configuring GTS parameters for packets of a certain queue. GTS for all traffic: configuring GTS parameters for all traffic. Configuring queue-based GTS Follow these steps to configure queue-based GTS: Enter system view system-view Enter interface view or port group view Enter interface view Enter port group view interface interface-type interface-number port-group manual port-group-name Use either command Settings in interface view take effect on the current interface; settings in port group view take effect on all ports in the port group. Configure GTS for a queue qos gts queue queue-number cir committed-information-rate [ cbs committed-burst-size ] CIR must be a multiple of 650. CBS must be a multiple of Configuring GTS for all traffic Follow these steps to configure GTS for all traffic: 4-5