Juniper Networks EX2500 manual Port Mirroring Overview

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Appendix A

Monitoring Ports with Port Mirroring

This appendix explains port mirroring to help you monitor ports and troubleshoot common problems on the EX2500 switch. The following topics are discussed in this appendix:

„Port Mirroring Overview on page 81

„Configuring Port Mirroring on page 82

Port Mirroring Overview

The port mirroring feature in the EX2500 switch allows you to copy traffic from specified ports and forward it to another port for monitoring or packet analysis. The port that receives the copied traffic is called the monitor port. The ports being monitored, and the traffic being copied, are considered to be mirrored.

The port mirroring feature can be used as a troubleshooting tool or to enhance the security of your network. You can attach a sniffer, or packet analysis device, to the monitor port and examine the mirrored traffic without disrupting traffic on the mirrored ports. As an example, an IDS server can be connected to the monitor port to detect intruders attacking the network.

The EX2500 switch can mirror all types of Layer 2 and Layer 3 traffic. Up to four monitor ports can be configured. Each monitor port can receive mirrored traffic from multiple switch ports, but each specific switch port is permitted to be mirrored to only one monitor port. For each mirrored port, you can also specify whether to mirror only ingress traffic (traffic entering the switch port), only egress traffic (traffic leaving the switch port), or both.

Figure 15 shows an example of port mirroring.

Figure 15: Monitoring Ports

Regular Switch Port Traffic

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Port Mirroring Overview „ 81

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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 Supported Platforms About This GuideObjectives AudienceIcon 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 Configure an entry in the notify table Configuring Snmp Trap HostsSNMPv1 Trap Host Configuration SNMPv2 Trap Host ConfigurationSNMPv3 Trap Host Configuration Securing Access to the SwitchConfigure the Radius secret Radius Authentication and AuthorizationHow Radius Authentication Works Configuring Radius on the SwitchRadius 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 SSH Encryption of Management Messages Configuring SSH Features on the SwitchGenerating RSA Host and Server Keys for SSH Access Secure ShellSSH 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 VLANsPvid Numbers „ Port configurationVLANs and Port Vlan ID Numbers Vlan 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 VLANsVerify the configuration Private Vlan Configuration GuidelinesPrivate Vlan Configuration Example Configure a secondary Vlan and map it to the primary VlanSpanning Tree Overview Spanning Tree ProtocolBridge Priority Bridge Protocol Data Units BPDUsDetermining the Path for Forwarding BPDUs Port Path Cost Spanning Tree Group Configuration GuidelinesChanging the Spanning Tree Mode Port PriorityAdding and Removing Ports from STGs Creating a VlanRules for Vlan Tagged Ports Port State Changes Rapid Spanning Tree ProtocolEdge Port Rstp Configuration GuidelinesRstp Configuration Example Port Type and Link TypePer Vlan Rapid Spanning Tree Default Spanning Tree ConfigurationWhy Do We Need Multiple Spanning Trees? Configuring Pvrst Pvrst Configuration GuidelinesCommon Internal Spanning Tree Mstp Configuration GuidelinesMultiple Spanning Tree Protocol Mstp RegionImplementing 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 „ Destination IP DIP Configurable Trunk Hash AlgorithmLink Aggregation Control Protocol „ Destination MAC Dmac48 „ Link Aggregation Control Protocol Set the Lacp mode Lacp Configuration GuidelinesConfiguring Lacp Optionally Reducing Lacp TimeoutEx2500config-if# lacp timeout short ex2500config-if# exit QoS Overview Quality of ServiceCOS Using ACL FiltersTo delete an IP Standard ACL MAC Extended ACLsIP Standard ACLs To delete a MAC Extended ACLTo delete an IP Extended ACL IP Extended ACLsTCP/UDP Understanding ACL PriorityACL Example 1-Blocking Traffic to a Host ACL Configuration ExamplesAssigning ACLs to a Port Viewing ACL StatisticsAdd 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 portRmon Group 2-History Configuring Rmon HistoryConfigure the Rmon History parameters for a port This configuration enables Rmon History collection on portConfigure the Rmon Alarm parameters to track Icmp messages Rmon Group 3-AlarmsAlarm MIB Objects Configuring Rmon AlarmsRmon 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 IndexInternet Group Management Protocol. See Igmp Management interface, configuringMulti-links between switches, port trunking Physical. See switch portsSegmentation. See IP subnets Segments. See IP subnets Quality of Service. See QoSQoS SecurityExample showing multiple VLANs Virtual Local Area Networks. See VLANs