Juniper Networks EX2500 manual Quality of Service, QoS Overview

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Chapter 5

Quality of Service

Quality of Service features allow you to allocate network resources to mission-critical applications at the expense of applications that are less sensitive to such factors as time delays or network congestion. You can configure your network to prioritize specific types of traffic, ensuring that each type receives the appropriate Quality of Service (QoS) level.

The following topics are discussed in this chapter:

QoS Overview on page 51

Using ACL Filters on page 52

Using Storm Control Filters on page 59

Using DSCP Values to Provide QoS on page 60

Using 802.1p Priority to Provide QoS on page 63

Queuing and Scheduling on page 64

QoS Overview

QoS helps you allocate guaranteed bandwidth to the critical applications, and limit bandwidth for less critical applications. Applications such as video and voice must have a certain amount of bandwidth to work correctly; using QoS, you can provide that bandwidth when necessary. Also, you can put a high priority on applications that are sensitive to timing out or that cannot tolerate delay, by assigning their traffic to a high-priority queue.

By assigning QoS levels to traffic flows on your network, you can ensure that network resources are allocated where they are needed most. QoS features allow you to prioritize network traffic, thereby providing better service for selected applications.

Figure 11 on page 52 shows the basic QoS model used by the switch.

QoS Overview 51

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Contents North Mathilda Avenue Sunnyvale, CA Configuration GuideIi „ Table of Contents Chapter VLANs Rmon Overview Rmon Group 1-Statistics Rmon Group 2-History Chapter Ports and TrunkingIndexes Port Mirroring Overview Configuring Port MirroringAppendixes Port-Based Vlan Assignment Default Vlan SettingsPage List of Tables EX2500 Ethernet Switch Configuration Guide „ List of Tables Objectives About This GuideAudience Supported PlatformsIcon Meaning Description Documentation ConventionsRequesting Technical Support List of Technical PublicationsDocumentation Feedback Opening a Case with Jtac Self-Help Online Tools and ResourcesEX2500 Ethernet Switch Applications Page Configuring the Management Interface Accessing the SwitchConfigure the default gateway. Enable the gateway Dynamic Host Configuration ProtocolUsing the EX2500 Web Device Manager Using TelnetConfiguring EX2500 Web Device Manager Access via Https Configuring EX2500 Web Device Manager Access via HttpSNMPv1, SNMPv2 Using SnmpSNMPv3 Default ConfigurationUser Configuration SNMPv1 Trap Host Configuration Configuring Snmp Trap HostsSNMPv2 Trap Host Configuration Configure an entry in the notify tableSNMPv3 Trap Host Configuration Securing Access to the SwitchHow Radius Authentication Works Radius Authentication and AuthorizationConfiguring Radius on the Switch Configure the Radius secretRadius Authentication Features in the EX2500 Switch Radius Attributes for EX2500 User Privileges Switch User AccountsTACACS+ Authentication Features in the EX2500 Switch TACACS+ AuthenticationHow TACACS+ Authentication Works „ starttime „ stoptime „ elapsedtime „ disccause Configure the TACACS+ secret and second secret Command Authorization and LoggingConfiguring TACACS+ Authentication on the Switch Generating RSA Host and Server Keys for SSH Access Configuring SSH Features on the SwitchSecure Shell SSH Encryption of Management MessagesSSH Integration with Radius and TACACS+ Authentication End User Access ControlUser Access Control Considerations for Configuring End User AccountsLogging In to an End User Account Listing Current UsersVlan Overview VLANsVLANs and Port Vlan ID Numbers „ Port configurationVlan Numbers Pvid NumbersVlan Tagging Illustrates the default Vlan settings on the switchDefault Vlan Settings Port-Based Vlan Assignment Vlan Topologies and Design Considerations Vlan Configuration RulesMultiple VLANs example in is described in Table Multiple VLANs Configuration ExampleEnable tagging on uplink ports that support multiple VLANs Private Vlan Ports Private VLANsPrivate Vlan Configuration Example Private Vlan Configuration GuidelinesConfigure a secondary Vlan and map it to the primary Vlan Verify the configurationSpanning Tree Overview Spanning Tree ProtocolBridge Priority Bridge Protocol Data Units BPDUsDetermining the Path for Forwarding BPDUs Changing the Spanning Tree Mode Spanning Tree Group Configuration GuidelinesPort Priority Port Path CostAdding and Removing Ports from STGs Creating a VlanRules for Vlan Tagged Ports Port State Changes Rapid Spanning Tree ProtocolRstp Configuration Example Rstp Configuration GuidelinesPort Type and Link Type Edge PortPer Vlan Rapid Spanning Tree Default Spanning Tree ConfigurationWhy Do We Need Multiple Spanning Trees? Configuring Pvrst Pvrst Configuration GuidelinesMultiple Spanning Tree Protocol Mstp Configuration GuidelinesMstp Region Common Internal Spanning TreeImplementing Multiple Spanning Tree Groups Multiple Spanning Tree Groups Configuration ExampleVlan Fast Uplink ConvergenceConfiguring Fast Uplink Convergence Configuration GuidelinesStatistical Load Distribution Ports and TrunkingTrunking Overview Trunk Group Configuration Rules Built-In Fault ToleranceBefore Configuring Static Trunks Port Trunk Group Configuration Example Port Trunking Configuration ExampleFollow these steps on the EX2500 switch Define a trunk group Link Aggregation Control Protocol Configurable Trunk Hash Algorithm„ Destination MAC Dmac „ Destination IP DIP48 „ Link Aggregation Control Protocol Configuring Lacp Lacp Configuration GuidelinesOptionally Reducing Lacp Timeout Set the Lacp modeEx2500config-if# lacp timeout short ex2500config-if# exit QoS Overview Quality of ServiceCOS Using ACL FiltersIP Standard ACLs MAC Extended ACLsTo delete a MAC Extended ACL To delete an IP Standard ACLTo delete an IP Extended ACL IP Extended ACLsTCP/UDP Understanding ACL PriorityAssigning ACLs to a Port ACL Configuration ExamplesViewing ACL Statistics ACL Example 1-Blocking Traffic to a HostAdd the ACL to a port ACL Example 3-Blocking Http TrafficAssign the ACLs to a port ACL Example 4-Blocking All Except Certain PacketsBroadcast Storms Using Storm Control FiltersConfiguring Storm Control Differentiated Services Concepts Using Dscp Values to Provide QoSAssured Forwarding Drop Precedence Class Per Hop BehaviorDscp Mapping Use the following command to perform Dscp mappingQoS Levels Shows the priority bits in a VLAN-tagged packet Using 802.1p Priority to Provide QoSQueuing and Scheduling Rmon Overview Remote MonitoringRmon Group 1-Statistics Configure the Rmon statistics on a portConfigure the Rmon History parameters for a port Configuring Rmon HistoryThis configuration enables Rmon History collection on port Rmon Group 2-HistoryAlarm MIB Objects Rmon Group 3-AlarmsConfiguring Rmon Alarms Configure the Rmon Alarm parameters to track Icmp messagesRmon Group 9-Events Ex2500config# rmon event 110 type log-onlyPage Igmp Snooping IgmpFastLeave IGMPv3 Snooping Igmp Snooping Configuration ExampleEx2500# show ip igmp groups Static Multicast RouterHigh Availability Overview High Availability Through Uplink Failure DetectionFailure Detection Pair Spanning Tree Protocol with UFD UFD Configuration GuidelinesMonitoring UFD UFD Configuration ExamplePage Appendixes EX2500 Ethernet Switch Configuration Guide 80 „ Appendixes Port Mirroring Overview „ Port Mirroring Overview on „ Configuring Port Mirroring onConfiguring Port Mirroring „ Index on IndexesEX2500 Ethernet Switch Configuration Guide 84 „ Indexes Numerics IndexMulti-links between switches, port trunking Management interface, configuringPhysical. See switch ports Internet Group Management Protocol. See IgmpQoS Quality of Service. See QoSSecurity Segmentation. See IP subnets Segments. See IP subnetsExample showing multiple VLANs Virtual Local Area Networks. See VLANs