3Com 3 manual How traffic is processed to provide Quality of Service

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Traffic Prioritization and your Switch

51

How traffic is processed to provide Quality of Service

A received packet at the ingress port is checked for its DSCP and IEEE 802.1D attributes to determine the level of service that the packet should receive.

802.1D packets are categorized into the 8 traffic classes defined by IEEE 802.1D; the higher the class the higher the priority given the packet on transmission.

DSCP packets are categorized into the six service levels as shown in Figure 12 and mapped to the appropriate queue.

The priority defined in the service level directs the packet to the appropriate egress queue. When a packet comes in with both 802.1D and DSCP priority markings, the higher of the priorities will be used.

Received packets in the Switch 4200 are only checked for DSCP and 802.1D attributes. No other attributes are supported.

Traffic queues are preset on a per-unit basis on the Switch 4200.

Configuring traffic prioritization for QoS on a Switch 4200

QoS can be configured on your Switch using the 3Com Network Supervisor or via the Command Line Interface (CLI).

The 3Com Network Supervisor application supplied on the CD-ROM accompanying your Switch is the main tool for configuring QoS, and 3Com recommends that you use this application to configure QoS.

You can also configure QoS via the command line interface (CLI). For a detailed description of the commands that you require refer to the Management Interface Reference Guide supplied in HTML format on the CD-ROM that accompanies your Switch.

Configure Quality of service in the Switch 4200 in the following way:

1Apply Traffic classification First identify the types of traffic requiring special treatment. These types are defined in the QoS feature through the creation of classifiers. The Switch 4200 supports two types of packet attributes on which to classify incoming traffic, Differentiated Services Code Point (DSCP) and IEEE 802.1D.

2Identify Service Levels You must then identify the level of service each classifier should receive. Note that DSCP service levels will be set

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Contents SuperStack 3Com Corporation 5400 Bayfront Plaza Santa Clara, California Contents Using Multicast Filtering Status Monitoring and Statistics IP Addressing About this Guide List conventions that are used throughout this guide ConventionsPddtechpubscomments@3com.com RelatedDocumentation CommentsRegistration ProductSwitch Features Page Software? What isSwitch Features ManagementSwitch Features Overview Flow Control Ports operating at 1000 Mbps only support full duplex modeFor more information about multicast filtering, see Using DuplexResilience Features For more information about STP and RSTP, see UsingQuality of Service For more information about Quality of Service, see UsingEvent Notification For more information about VLANs, see Setting Up Virtual Port Features Ports operating at 1000 Mbps support full duplex mode only Port Features Switch units connected using an aggregated link Aggregated Links Traffic Distribution and Link Failure on Aggregated Links 2 Gbps aggregated link between two Switch units Optimizing Bandwidth Relevant multicast group Using Multicast FilteringUsing Multicast Filtering Query mode Snooping ModeQuery Mode Enabling Igmp Multicast Learning Igmp v2 protocolThat support IP Igmp multicast filtering works as followsIgmp Multicast Filtering Using Multicast Filtering Spanning Tree Protocol STPNetwork Ieee 802.1w standard What is STP? Traffic flowing through Bridge B Port Speed Link Type Path Cost 802.1D-1998 802.1w Using Resilience Features Port costs in a network Configuration 1 Redundancy for Backbone Link Configuration 2 Redundancy through Meshed BackboneConfiguration 3 Redundancy for Cabling Error STP configurations Multiple VLANs Default BehaviorUsing STP on a Network withConfiguration that separates VLANs Using Resilience Features Database Entries What is the SwitchHow Switch Database?Databases entries can have three states Switch Database Entry StatesConverged network applications Used by organizations with a What is TrafficPrioritization? Available802.1D Priority Levels How Traffic Prioritization Works Traffic Prioritization Your SwitchConfiguring traffic prioritization for QoS on a Switch How traffic is processed to provide Quality of ServiceUsing Traffic Prioritization What is RMON? Network efficiency and reduce the load on your networkThat allows you to monitor the traffic of LANs or VLANs Alarms EventsIt improves your efficiency Rmon SwitchLow Threshold Statistic High Threshold Recovery Period Low Threshold Statistic High Threshold Recovery Status Monitoring and Statistics Hardware Status Monitoring Example device summary web Setting UP Virtual Lans VLANs provide extra security VLANs ease the movement of devices on networksVLANs help to control traffic Creating an Ieee 802.1Q Tagged Link MembershipTwo Vlans connected via a router Examples ConfigurationUsing Untagged Configure the VLANsConfigure the VLANs on Switch Add endstation ports on Switch 1 to the VLANsAdd ports to the VLANs Check the Vlan membership for both switches Add port 12 on Switch 1 to the VLANsAdd endstation ports on Switch 2 to the VLANs Add port 11 on Switch 2 to the VLANsConfiguration How Automatic IP How Your SwitchObtains IP InformationHow Automatic IP Configuration Works Automatic IP configuration feature That a Switch may change its IP address whilst in useConsiderations Index Configuration RulesIP Addressing GlossaryPage Configuration Rules for Gigabit Ethernet Configuration RulesFast Ethernet configuration rules Configuration Rules for Fast Ethernet Appendix a Configuration Rules This chapter contains the following sections NetworkExample Segments are connected to the Switch which is positionedSimple Network Family and 4900 family can be used in your networkDual Speed Hub Switch Network Advanced NetworkImproving Resilience of YourEnhancing PerformanceTherefore the overall network performance Simple Overview IP AddressesIP Address Obtaining a Registered IP AddressDotted Decimal Notation Decimal value of an octet whose bits are all 1s isNetwork Portion Subnet mask Extending the Network Prefix Subnet Mask NumberingOr leave the field blank Glossary Glossary Fast Ethernet EndstationEthernet Ethernet addressIeee 802.1D GatewayHalf duplex HubLine speed See baud Glossary Rstp See Rapid Spanning Tree Protocol STP See Spanning Tree Protocol STP Page Glossary Numbers IndexIgmp multicast filtering 30 Internet Addresses 85 InterNIC Sub-networks. See subnets Switch Database

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