Dell N2000, N3000, N4000 body

Monitoring and Logging System Information 273

logging email test

message-type {urgent |

non-urgent | both}

message-body

body

Send a test email to the configured recipient to verify that

the feature is properly configured.

CTRL + Z Exit to Privileged EXEC mode.

show logging email

config

View the configured settings for email alerts.

show logging email

statistics

View information about the number of emails sent and the

time they were sent.

clear logging email

statistics

Clear the email alerting statistics.

Command Purpose

Contents

Main Notes and Cautions ____________ Contents 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . 51 2 Switch Feature Overview . . . . . . . . . . . . 55 Page Page Page 3 Hardware Overview. . . . . . . . . . . . . . . . . 91 4 Using Dell OpenManage Switch Administrator . . . . . . . . . . . . . . . . . . . . 127 5 Using the Command-Line Interface. . . . 135 Page Page 10 Configuring Authentication, Authorization, and Accounting . . . . . . . 207 Page 11 Monitoring and Logging System Information . . . . . . . . . . . . . . . . . . . . . . 243 12 Managing General System Settings . . . 279 13 Configuring SNMP . . . . . . . . . . . . . . . . . 323 14 Managing Images and Files . . . . . . . . . 359 15 Automatically Updating the Image and Configuration . . . . . . . . . . . . . . . . . 389 16 Monitoring Switch Traffic . . . . . . . . . . . 407 Page 17 Configuring iSCSI Optimization . . . . . . . 459 18 Configuring Port Characteristics. . . . . . 477 19 Configuring Port and System Security . . . . . . . . . . . . . . . . . . . . . . . . . 503 20 Configuring Access Control Lists . . . . . 583 21 Configuring VLANs. . . . . . . . . . . . . . . . . 645 Page 22 Configuring the Spanning Tree Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 715 23 Discovering Network Devices. . . . . . . . 761 24 Configuring Port-Based Traffic Control . . . . . . . . . . . . . . . . . . . . . . . . . . 787 25 Configuring L2 Multicast Features . . . . 803 26 Configuring Connectivity Fault Management . . . . . . . . . . . . . . . . . . . . . 859 27 Snooping and Inspecting Traffic. . . . . . 879 Page 28 Configuring Link Aggregation . . . . . . . . 913 29 Configuring Data Center Bridging Features . . . . . . . . . . . . . . . . . . . . . . . . 983 30 Managing the MAC Address Table . . . 1015 31 Configuring Routing Interfaces. . . . . . 1021 32 Configuring DHCP Server and Relay Settings . . . . . . . . . . . . . . . . . . . . . . . . 1037 33 Configuring IP Routing. . . . . . . . . . . . . 1063 34 Configuring L2 and L3 Relay Features . . . . . . . . . . . . . . . . . . . . . . . 1087 35 Configuring OSPF and OSPFv3 . . . . . . . 1111 Page 36 Configuring RIP . . . . . . . . . . . . . . . . . . 1201 37 Configuring VRRP . . . . . . . . . . . . . . . . 1217 38 Configuring IPv6 Routing. . . . . . . . . . . 1241 39 Configuring DHCPv6 Server and Relay Settings . . . . . . . . . . . . . . . . . . . 1265 40 Configuring Differentiated Services . . 1285 41 Configuring Class-of-Service . . . . . . . 1313 42 Configuring Auto VoIP . . . . . . . . . . . . . 1331 43 Managing IPv4 and IPv6 Multicast . . . 1337 Page Page Page Page Introduction About This Document Audience Document Conventions Additional Documentation Getting Started Guide CLI Reference Guide Page Switch Feature Overview System Management Features Multiple Management Options System Time Management Log Messages Integrated DHCP Server Management of Basic Network Information IPv6 Management Features Dual Software Images File Management Switch Database Management Templates Automatic Installation of Firmware and Configuration sFlow SNMP Alarms and Trap Logs CDP Interoperability through ISDP Remote Monitoring (RMON) Stacking Features High Stack Count Single IP Management Master Failover with Transparent Transition standby Nonstop Forwarding on the Stack Hot Add/Delete and Firmware Synchronization Security Features Configurable Access and Authentication Profiles Password-Protected Management Access Strong Password Enforcement TACACS+ Client RADIUS Support SSH/SSL Inbound Telnet Control Denial of Service Port Protection Captive Portal Dot1x Authentication (IEEE 802.1X) MAC-Based 802.1X Authentication Dot1x Monitor Mode MAC-Based Port Security Access Control Lists (ACL) Time-Based ACLs IP Source Guard (IPSG) DHCP Snooping Dynamic ARP Inspection Protected Ports (Private VLAN Edge) Green Technology Features Energy Detect Mode Energy Efficient Ethernet Power Utilization Reporting Power over Ethernet (PoE) Plus Features Power Over Ethernet (PoE) Plus Configuration PoE Plus Support Switching Features Flow Control Support (IEEE 802.3x) CLI Reference Guide Head of Line Blocking Prevention Alternate Store and Forward (ASF) Auto-MDI/MDIX Support VLAN-Aware MAC-based Switching Back Pressure Support Auto Negotiation Broadcast Storm Control Port Mirroring Static and Dynamic MAC Address Tables Link Layer Discovery Protocol (LLDP) Link Layer Discovery Protocol (LLDP) for Media Endpoint Devices Connectivity Fault Management (IEEE 802.1ag) Priority-based Flow Control (PFC) Data Center Bridging Exchange (DBCx) Protocol Enhanced Transmission Selection Cisco Protocol Filtering DHCP Layer 2 Relay Virtual Local Area Network Supported Features GARP and GVRP Support Guest VLAN Double VLANs Spanning Tree Protocol Features Spanning Tree Protocol (STP) Spanning Tree Port Settings Rapid Spanning Tree Multiple Spanning Tree Page Link Aggregation Features Link Aggregation Link Aggregate Control Protocol (LACP) Multi-Switch LAG (MLAG) Routing Features Address Resolution Protocol (ARP) Table Management VLAN Routing IP Configuration Open Shortest Path First (OSPF) BOOTP/DHCP Relay Agent IP Helper and UDP Relay Routing Information Protocol Router Discovery Routing Table Virtual Router Redundancy Protocol (VRRP) Tunnel and Loopback Interfaces IPv6 Routing Features IPv6 Configuration IPv6 Routes OSPFv3 DHCPv6 Quality of Service (QoS) Features Differentiated Services (DiffServ) Class Of Service (CoS) Auto Voice over IP (VoIP) Internet Small Computer System Interface (iSCSI) Optimization Layer 2 Multicast Features MAC Multicast Support IGMP Snooping IGMP Snooping Querier MLD Snooping Multicast VLAN Registration Layer 3 Multicast Features Distance Vector Multicast Routing Protocol Internet Group Management Protocol IGMP Proxy Protocol Independent MulticastDense Mode Protocol Independent MulticastSparse Mode Protocol Independent MulticastSource Specific Multicast Protocol Independent Multicast IPv6 Support MLD/MLDv2 (RFC2710/RFC3810) Hardware Overview Dell Networking N2000 Series Switch Hardware N2000 Series Front Panel Page Page Page N2000 Series Back Panel Page N2000 LED Definitions Stacking Port LEDs System LEDs 100 Power Consumption for N2000 Series PoE Switches Table3-5 shows power consumption data for the PoE-enabled switches. Hardware Overview 101 Table 3-6. N2000 Series PoE Power Budget Limit One PSU Support Two PSUs Support Dell Networking N3000 Series Switch Hardware N3000 Series Front Panel Page Page Page Users Configuration Guide. N3000 Series Back Panel Page Page LED Definitions 110 Module Bay LEDs Page 112 System LEDs Power Consumption for N3000 Series PoE Switches Table 3-15. N3000 Series PoE Power Budget Limit One PSU Support Two PSUs Support Dell Networking N4000 Series Switch Hardware Front Panel Page Page Page N4000 Back Panel Page LED Definitions 122 Module Bay LEDs Page 124 Table3-21 shows the System LED definitions for the N4000 series switches. Hardware Overview 125 Switch MAC Addresses Shown below are three commands that display the MAC addresses used by the switch: Page Using Dell OpenManage Switch Administrator About Dell OpenManage Switch Administrator Starting the Application Understanding the Interface Page Using the Switch Administrator Buttons and Links Defining Fields Understanding the Device View Using the Device View Port Features Using the Device View Switch Locator Feature Page Using the Command-Line Interface Accessing the Switch Through the CLI Getting Started Guide Console Connection Telnet Connection Understanding Command Modes CLI Reference Guide 138 console> console# console(config)# console(config- if)# Entering CLI Commands Using the Question Mark to Get Help Using Command Completion Entering Abbreviated Commands Negating Commands Command Output Paging Understanding Error Messages Recalling Commands from the History Buffer 142 Default Settings 144 Page 146 Setting the IP Address and Other Basic Network Information IP Address and Network Information Overview What Is the Basic Network Information? Why Is Basic Network Information Needed? How Is Basic Network Information Configured? Getting Started Guide What Is Out-of-Band Management and In-Band Management? Page Destination Unreachable, Fragmentation needed but DF set Default Network Information Configuring Basic Network Information (Web) Out-of-Band Interface IP Interface Configuration (Default VLAN IP Address) Page Route Entry Configuration (Switch Default Gateway) Page Domain Name Server Default Domain Name Host Name Mapping Dynamic Host Name Mapping Configuring Basic Network Information (CLI) Enabling the DHCP Client on the OOB Port Enabling the DHCP Client on the Default VLAN 162 Managing DHCP Leases prefix/prefixlien Configuring Static Network Information on the OOB Port Configuring Static Network Information on the Default VLAN Configuring and Viewing Additional Network Information name ip_address Basic Network Information Configuration Example Page Page Managing QSFP Ports Page Managing a Switch Stack Stacking Overview Page Page Dell Networking N2000, N3000, and N4000 Stacking Compatibility How is the Stack Master Selected? unassigned Adding a Switch to the Stack Removing a Switch from the Stack unit How is the Firmware Updated on the Stack? What is Stacking Standby? What is Nonstop Forwarding? Page Page Switch Stack MAC Addressing and Stack Design Considerations NSF Network Design Considerations Why is Stacking Needed? Default Stacking Values Page Managing and Monitoring the Stack (Web) Unit Configuration Stack Summary Stack Firmware Synchronization Supported Switches Stack Port Summary Page NSF Summary Page Managing the Stack (CLI) Dell Networking N2000, N3000, and N4000 Series Switches CLI Reference Guide Configuring Stack Member, Stack Port, and NSF Settings unit SID (N4000 only). NOTE: 194 Viewing and Clearing Stacking and NSF Information stack- member-number] Stacking and NSF Usage Scenarios Basic Failover Page Preconfiguring a Stack Member Page NSF in the Data Center NSF and VoIP NSF and DHCP Snooping trusted NSF and the Storage Access Network Page NSF and Routed Access Page Page Configuring Authentication, Authorization, and Accounting AAA Overview Methods Access Lines Page Authentication Authentication Types Authorization Exec Authorization Capabilities Page Accounting Authentication Examples Local Authentication Example Page TACACS+ Authentication Example Public Key SSH Authentication Example Page Page Page Page Page Page RADIUS Authentication Example Page Authorization Examples Local Authorization ExampleDirect Login to Privileged EXEC Mode TACACS+ Authorization ExampleDirect Login to Privileged EXEC Mode TACACS+ Authorization ExampleAdministrative Profiles TACACS+ Authorization ExampleCustom Administrative Profile regex mode-name number TACACS+ Authorization ExamplePer-command Authorization RADIUS Authorization ExampleDirect Login to Privileged EXEC Mode RADIUS Authorization ExampleAdministrative Profiles Using RADIUS Servers to Control Management Access How Does RADIUS Control Management Access? Page secrets Which RADIUS Attributes Does the Switch Support? Page How Are RADIUS Attributes Processed on the Switch? Using TACACS+ Servers to Control Management Access Which TACACS+ Attributes Does the Switch Support? Default Configurations Method Lists Access Lines (AAA) Access Lines (Non-AAA) Administrative Profiles profile name Page Page Monitoring and Logging System Information System Monitoring Overview What System Information Is Monitored? Why Is System Information Needed? Where Are Log Messages Sent? What Are the Severity Levels? What Are the System Startup and Operation Logs? What Is the Log Message Format? What Factors Should Be Considered When Configuring Logging? Default Log Settings Monitoring System Information and Configuring Logging (Web) Device Information Page System Health System Resources Unit Power Usage History Integrated Cable Test for Copper Cables Optical Transceiver Diagnostics Page Log Global Settings RAM Log Log File Syslog Server Page Page Email Alert Global Configuration Email Alert Mail Server Configuration Page Email Alert Subject Configuration Email Alert To Address Configuration Email Alert Statistics Monitoring System Information and Configuring Logging (CLI) Dell Networking N2000, N3000, and N4000 Series Switches CLI Reference Guide Viewing System Information and Enabling the Locator LED 268 Running Cable Diagnostics Beginning in Privileged EXEC mode, use the following commands to run the cable diagnostic tests. NOTE: Configuring Local Logging severity disc-name facility- facility- Configuring Remote Logging udp-port description Configuring Mail Server Settings 272 Configuring Email Alerts for Log Messages subject email-address minutes body Logging Configuration Examples Configuring Local and Remote Logging Page Configuring Email Alerting Page Page Managing General System Settings System Settings Overview Page Why Does System Information Need to Be Configured? What Are SDM Templates? Page Why is the System Time Needed? How Does SNTP Work? What Configuration Is Required for Plug-In Modules? What Are the Key PoE Plus Features for the N2024P/N2048P and N3024P/N3048P Switches? Table12-4 describes some of the key PoE Plus features the switches support. Default General System Information Configuring General System Settings (Web) System Information Page Page CLI Banner SDM Template Preference Clock SNTP Global Settings SNTP Authentication Page SNTP Server Page Page Summer Time Configuration Time Zone Configuration Card Configuration Slot Summary Supported Cards Power Over Ethernet Global Configuration (N2024P/N2048P and N3024P/N3048P Only) Power Over Ethernet Interface Configuration (N2024P/N2048P and N3024P/N3048P Only) Page Configuring System Settings (CLI) Configuring System Information Configuring the Banner Managing the SDM Template Configuring SNTP Authentication and an SNTP Server ip_address key_id Setting the System Time and Date Manually offset hh:mm month day Configuring the Expansion Slots (N3000 Series Only) year hh:mm year hh:mm Viewing Slot Information (N4000 Series Only) Use the following commands to view information about Slot 0 and its support. threshold threshold Configuring PoE Settings (N2024P/N2048P and N3024P/N3048P Only) limit General System Settings Configuration Examples Configuring System and Banner Information Page Page Page Configuring SNTP Page Configuring the Time Manually Page Configuring SNMP SNMP Overview What Is SNMP? What Are SNMP Traps? Why Is SNMP Needed? Default SNMP Values Page Configuring SNMP (Web) SNMP Global Parameters SNMP View Settings Page Access Control Group Page SNMPv3 User Security Model (USM) Page Page Communities Page Notification Filter Notification Recipients Page Trap Flags OSPFv2 Trap Flags OSPFv3 Trap Flags Trap L og Page Configuring SNMP (CLI) Configuring the SNMPv3 Engine ID 346 engineid-string 1.3.*.4 Configuring SNMP Views, Groups, and Users view- name oid-tree groupname groupname view-name username groupname username des-key sha-key md5-key Configuring Communities group_name ip_address view-name community string group-name group-name community-string . Configuring SNMP Notifications (Traps and Informs) 1.3.*.4 system 1.3.6.2.4 oid-tree host- addr retries filtername community-string retries ip- username filter-name retries username SNMP Configuration Examples Configuring SNMPv1 and SNMPv2 public private public Configuring SNMPv3 internet group_snmpv3 view_snmpv3 admin admin Configuring SNMP 357 console#show snmp views console#show snmp group console#show snmp user Page Managing Images and Files Image and File Management Overview What Files Can Be Managed? Page Why Is File Management Needed? Page What Methods Are Supported for File Management? What Factors Should Be Considered When Managing Files? Page How Is the Running Configuration Saved? Managing Images and Files (Web) File System Active Images backup active USB Flash Drive File Download Page File Upload Page Copy Files Managing Images and Files (CLI) Downloading and Activating a New Image (TFTP) active backup Managing Files in Internal Flash filename current_name new_name Page Managing Files on a USB Flash Device Uploading a Configuration File (SCP) 380 Managing Configuration Scripts (SFTP) File and Image Management Configuration Examples Upgrading the Firmware Page Page Managing Configuration Scripts Page Managing Files by Using the USB Flash Drive Page Page Automatically Updating the Image and Configuration Auto Configuration Overview What Is USB Auto Configuration? What Files Does USB Auto Configuration Use? How Does USB Auto Configuration Use the Files on the USB Device? What Is the Setup File Format? What Is the DHCP Auto Configuration Process? file sname sname siaddr siaddr file address Page Monitoring and Completing the DHCP Auto Configuration Process What Are the Dependencies for DHCP Auto Configuration? 400 Default Auto Configuration Values Table15-3 describes the Auto Configuration defaults. Managing Auto Configuration (Web) Auto-Install Configuration Managing Auto Configuration (CLI) Managing Auto Configuration Auto Configuration Example Enabling USB Auto Configuration and Auto Image Download Page Enabling DHCP Auto Configuration and Auto Image Download yiaddr siaddr sname Easy Image Upgrade via USB Monitoring Switch Traffic Traffic Monitoring Overview What is sFlow Technology? Page Page What is RMON? What is Port Mirroring? Port Mirroring Behaviors Remote Capture Why is Traffic Monitoring Needed? Default Traffic Monitoring Values Monitoring Switch Traffic (Web) sFlow Agent Summary Page sFlow Receiver Configuration sFlow Sampler Configuration sFlow Poll Configuration Interface Statistics Etherlike Statistics GVRP Statistics EAP Statistics . Utilization Summary Counter Summary Switchport Statistics RMON Statistics RMON History Control Statistics Page RMON History Table RMON Event Control Page RMON Event Log RMON Alarms Page Port Statistics LAG Statistics Port Mirroring Page Monitoring Switch Traffic (CLI) owner_string rcvr_index at support.dell.com/manuals. Configuring sFlow rcvr-index if_type if_number poll- poll-interval size n rcvr-index if_type if_number sampling-rate Configuring RMON rcvr-index community community size number variable interval number string variable value Viewing Statistics ownername interface port-channel econds Configuring Port Mirroring session_number Use the following commands in Privileged EXEC mode to configure a port mirroring session. Configuring RSPAN interface_id Configuring RSPAN (Source Switch) Configuring RSPAN (Transit Switch) Configuring RSPAN (Destination Switch) Traffic Monitoring Configuration Examples Configuring sFlow Page Configuring RMON Configuring Remote Capture Page Page Page Page Configuring RSPAN Page Page Page Configuring iSCSI Optimization iSCSI Optimization Overview What Does iSCSI Optimization Do? How Does the Switch Detect iSCSI Traffic Flows? How Is Quality of Service Applied to iSCSI Traffic Flows? How Does iSCSI Optimization Use ACLs? What Information Does the Switch Track in iSCSI Traffic Flows? How Does iSCSI Optimization Interact With Dell EqualLogic Arrays? What Occurs When iSCSI Optimization Is Enabled or Disabled? How Does iSCSI Optimization Interact with DCBx? How Does iSCSI Optimization Interact with Dell Compellent Arrays? iSCSI CoS and Priority Flow Control/Enhanced Transmission Selection Interactions 466 Default iSCSI Optimization Values Table17-1 shows the default values for the iS CSI optimization feature. Configuring iSCSI Optimization (Web) iSCSI Global Configuration iSCSI Targets Table iSCSI Sessions Table Page Configuring iSCSI Optimization (CLI) targetname tcp-port-n targetname tcp-port-2...tcp-port-16 472 vtp iSCSI Optimization Configuration Examples Configuring iSCSI Optimization Between Servers and a Disk Array Page Page Page Configuring Port Characteristics Port Overview What Physical Port Characteristics Can Be Configured? 478 What is Link Dependency? Page What Interface Types are Supported? What is Interface Configuration Mode? Page What Are the Green Ethernet Features? Page Default Port Values Configuring Port Characteristics (Web) Port Configuration Page Page Link Dependency Configuration Page Link Dependency Summary Port Green Ethernet Configuration Port Green Ethernet Statistics Page Port Green Ethernet LPI History Configuring Port Characteristics (CLI) Configuring Port Settings Configuring Link Dependencies 498 group_id Configuring Green Features max interface Port Configuration Examples Configuring Port Settings Configuring a Link Dependency Groups Page Configuring Port and System Security Port-based SecurityIEEE 802.1X and Port MAC Locking IEEE 802.1X Page Page quarantine Page unblock Page Page 512 Configuring IEEE 802.1X (Web) Page Page Page Page Page Page Page Dell Networking N2000, N3000, and N4000 Series Switches CLI Reference Guide NOTE: 522 Configuring Additional 802.1X Interface Settings NOTE: Configuring 802.1X Settings for RADIUS-Assigned VLANs users NOTE: interface 524 NOTE: Page Page secret Page 9 Configuring Port and System Security 529 View a summary of the port status. console#show dot1x Page Page Page Page Page Page cl-http con-pol Page Page Port Security (Port-MAC Locking) Page Page 542 Configuring Port Security (CLI) max- addr Captive Portal Captive Portal Overview Page Page Page Page Default Captive Portal Behavior and Settings Page Configuring the Captive Portal (Web) Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page Page 568 Configuring Captive Portal (CLI) at support.dell.com/manuals. Configuring Global Captive Portal Settings Creating and Configuring a Captive Portal url group-number Configuring Captive Portal Groups and Users cp-id NOTE: group-id name user-id new-group-id new-group-id Page Captive Portal Configuration Example Page Page Page Authentication Manager Authentication Restart 802.1X Interaction Authentication Priority Configuration Example802.1X and MAB Page Denial of Service Configuring Access Control Lists ACL Overview What Are MAC ACLs? What Are IP ACLs? What Is the ACL Redirect Function? What Is the ACL Mirror Function? What Is ACL Logging What Are Time-Based ACLs? What Are the ACL Limitations? Page Page Page ACL Configuration Details How Are ACLs Configured? Editing Access Lists Preventing False ACL Matches Page Using IP and MAC Address Masks Policy Based Routing Page Limitations Page Examples Configuring ACLs (Web) IP ACL Configuration Page IP ACL Rule Configuration Page MAC ACL Configuration Page MAC ACL Rule Configuration IPv6 ACL Configuration IPv6 ACL Rule Configuration Page ACL Binding Configuration Time Range Entry Configuration Page Configuring ACLs (CLI) Configuring an IPv4 ACL Page precedence tosmask tos icmp-type icmp-message icmp-code is igmp-type unit/slot/ port rate burst-size direction seqnum 618 Configuring a MAC ACL 0x0600-0xFFFF ethertypekey destmacmask dstmac destination-ipv6-prefix host is dscp tosmask icmp-type icmp-code icmp-message unit/slot/ port rate burst-size direction seqnum Configuring an IPv6 ACL source-ipv6- every endport startport 0-65535 destination ipv6 prefix value dscp name direction seq- num Configuring a Time Range time date date days-of-the- week time days-of- the-week days-of-the-week days-of-the-week ACL Configuration Examples Basic Rules Internal System ACLs Complete ACL Example Page Page Page Advanced Examples Page Page Page Page Page Configuring Access Control Lists 639 A Consolidated DoS Example traffic coming to the CPU. NOTE: Policy Based Routing Examples ACL That Matches All IP Packets Page 642 Figure 20-14. Policy Based Routing on VLAN Interfaces Example Create VLANs 10, 20, 30 and 40 Add VLAN Membership to Physical Ports Also, configure the native VLAN on the corresponding interfaces: Page Match-ip-1_1_1_2-to-2_2_2_2 Redirect_to_3_3_3_3 Configuring VLANs VLAN Overview default Page Switchport Modes VLAN Tagging GVRP Double-VLAN Tagging Page Page Private VLANs Page Page Page Page Page Additional VLAN Features Default VLAN Behavior 662 Table21-7 shows the default values or maximum values for VLAN features. Configuring VLANs (Web) VLAN Membership Page Page Page Page VLAN Port Settings VLAN LAG Settings Page Bind MAC to VLAN Bind IP Subnet to VLAN GVRP Parameters Page Protocol Group Adding a Protocol Group Page Double VLAN Global Configuration Double VLAN Interface Configuration Page Page Configuring VLANs (CLI) Creating a VLAN Configuring a Port in Access Mode Configuring a Port in Trunk Mode Page list vlan- atom interface vlan-id vlan-atom Configuring a Port in General Mode Page Configuring VLAN Settings for a LAG Configuring Double VLAN Tagging Page Configuring MAC-Based VLANs 692 Configuring IP-Based VLANs ip-address subnet-mask ip-address ip- mask ] Configuring a Protocol-Based VLAN groupid Configuring GVRP vlan-list list Page Configuring Voice VLANs VLAN Configuration Examples Page 700 Table21-10 shows the port assignments on the switches. Configuring VLANs Using Dell OpenManage Administrator Page Page Page Configure the VLANs and Ports on Switch 2 Configuring VLANs Using the CLI Page Page Page Configuring a Voice VLAN Page Page Configuring VLANs 713 Page Configuring the Spanning Tree Protocol STP Overview What Are Classic STP, Multiple STP, and Rapid STP? How Does STP Work? How Does MSTP Operate in the Network? Page Page Page MSTP with Multiple Forwarding Paths What are the Optional STP Features? loop- inconsistent blocking state RSTP-PV DirectLink Rapid Convergence Page IndirectLink Rapid Convergence Feature Page Interoperability Between STP-PV and RSTP-PV Modes Interoperability With IEEE Spanning Tree Protocols Page Page Page Configuration Examples Default STP Values Configuring Spanning Tree (Web) STP Global Settings Page STP Port Settings Page STP LAG Settings Rapid Spanning Tree Page MSTP Settings Page MSTP Interface Settings 746 Configuring Spanning Tree (CLI) hops at support.dell.com/manuals. Configuring Global STP Bridge Settings Configuring Optional STP Features 748 Configuring STP Interface Settings Configuring MSTP Switch Settings priority instance-id vlan-range instance-ID Configuring MSTP Interface Settings priority instance-ID cost instance-ID STP Configuration Examples STP Configuration Example Page MSTP Configuration Example Page Page RSTP-PV Access Switch Configuration Example Page Page Page Page Discovering Network Devices Device Discovery Overview What Is ISDP? What is LLDP? What is LLDP-MED? Why are Device Discovery Protocols Needed? Default IDSP and LLDP Values Page Configuring ISDP and LLDP (Web) ISDP Global Configuration ISDP Cache Table ISDP Interface Configuration ISDP Statistics LLDP Configuration Page LLDP Statistics LLDP Connections Page LLDP-MED Global Configuration LLDP-MED Interface Configuration LLDP-MED Local Device Information LLDP-MED Remote Device Information Configuring ISDP and LLDP (CLI) Configuring Global ISDP Settings Enabling ISDP on a Port Viewing and Clearing ISDP Information Configuring Global LLDP Settings reinit-delay hold-value transmit-interval hold-value Viewing and Clearing LLDP Information Configuring LLDP-MED Settings Viewing LLDP-MED Information Device Discovery Configuration Examples Configuring ISDP Configuring LLDP Page Page Page Configuring Port-Based Traffic Control Port-Based Traffic Control Overview What is Flow Control? What is Storm Control? What are Protected Ports? What is Link Local Protocol Filtering? Default Port-Based Traffic Control Values Configuring Port-Based Traffic Control (Web) Flow Control (Global Port Parameters) Storm Control Page Protected Port Configuration Page LLPF Configuration Page 798 Configuring Port-Based Traffic Control (CLI) at support.dell.com/manuals. Configuring Flow Control and Storm Control Configuring Protected Ports groupid 800 Configuring LLPF Beginning in Privileged EXEC mode, use the following commands to configure LLPF settings. Port-Based Traffic Control Configuration Example Page Configuring L2 Multicast Features L2 Multicast Overview Multicast Flooding and Forwarding What Are the Multicast Bridging Features? What Is L2 Multicast Traffic? What Is IGMP Snooping? Page What Is MLD Snooping? What Is Multicast VLAN Registration? When Are L3 Multicast Features Required? What Are GARP and GMRP? Page Snooping Switch Restrictions Partial IGMPv3 and MLDv2 Support MAC Address-Based Multicast Group IGMP/MLD Snooping in a Multicast Router Page 814 Default L2 Multicast Values Details about the L2 multicast are in Table 25-1. Page Configuring L2 Multicast Features (Web) Multicast Global Parameters Bridge Multicast Group Page Page MRouter Status General IGMP Snooping Page Page Global Querier Configuration VLAN Querier Page VLAN Querier Status MFDB IGMP Snooping Table MLD Snooping General Page MLD Snooping Global Querier Configuration MLD Snooping VLAN Querier Page MLD Snooping VLAN Querier Status MFDB MLD Snooping Table MVR Global Configuration MVR Members MVR Interface Configuration Page MVR Statistics GARP Timers Page GMRP Parameters Page MFDB GMRP Table 846 Configuring L2 Multicast Features (CLI) interface-list ip- multicast-address mac-multicast-address interface-list Configuring IGMP Snooping on VLANs 848 Configuring IGMP Snooping Querier Configuring MLD Snooping on VLANs 850 Configuring MLD Snooping Querier ipv6-address Configuring MVR interval-count mcast-address groups mcast-address group mcast-address Configuring GARP Timers and GMRP timer_value Case Study on a Real-World Network Topology Multicast Snooping Case Study Page Page Page Page Configuring Connectivity Fault Management Dot1ag Overview How Does Dot1ag Work Across a CarrierNetwork? What Entities Make Up a MaintenanceDomain? Page What is the Administrators Role? Default Dot1ag Values Configuring Dot1ag (Web) Dot1ag Global Configuration Dot1ag MD Configuration Dot1ag MA Configuration Dot1ag MEP Configuration Dot1ag MIP Configuration Dot1ag RMEP Summary Dot1ag L2 Ping Dot1ag L2 Traceroute Dot1ag L2 Traceroute Cache Dot1ag Statistics Configuring Dot1ag (CLI) name level vlan-id level Configuring MEP Information Dot1ag Ping and Traceroute Dot1ag Configuration Example Page Page Snooping and Inspecting Traffic Traffic Snooping and Inspection Overview What Is DHCP Snooping? How Is the DHCP Snooping Bindings DatabasePopulated? Page What Is IP Source Guard? n n > m n m What is Dynamic ARP Inspection? Why Is Traffic Snooping and Inspection Necessary? Default Traffic Snooping and Inspection Values Page Configuring Traffic Snooping and Inspection (Web) DHCP Snooping Configuration DHCP Snooping Interface Configuration Page DHCP Snooping VLAN Configuration DHCP Snooping Persistent Configuration DHCP Snooping Static Bindings Configuration DHCP Snooping Dynamic Bindings Summary DHCP Snooping Statistics IPSG Interface Configuration IPSG Binding Configuration IPSG Binding Summary DAI Global Configuration DAI Interface Configuration Page DAI VLAN Configuration DAI ACL Configuration DAI ACL Rule Configuration DAI Statistics Page 904 Configuring Traffic Snooping and Inspection (CLI) filename hostIP hostIP/filename mac-address rate vlan id 906 Configuring IP Source Guard ipaddr mac_addr ipaddr mac_addr Configuring Dynamic ARP Inspection acl-name sender-ip pps pps acl-name sender-mac sender-ip sender-mac Page Traffic Snooping and Inspection Configuration Examples Configuring DHCP Snooping Page Configuring IPSG Configuring Link Aggregation Link Aggregation Page Page Page Default Link Aggregation Values Configuring Link Aggregation (Web) Page Page Page Page Page Page Configuring Link Aggregation (CLI) 926 Configuring Link Aggregation Groups port-channel-number port- channel-number Configuring LACP Parameters mode port-channel port-channel- Page Link Aggregation Configuration Examples Page Page Multi-Switch LAG (MLAG) Deployment Scenarios MLAG Definitions Configuration Consistency Page Page Operation in the Network Peer-Link MLAG 1 MLAG 2 A B C Page Page L2 Configuration Steps Page Page Switch Firmware Upgrade Procedure Static Routing on MLAG Interfaces Page Page Page Page Peer-Link Router MLAG VLAN 30 VLAN 20 Router or Switch Failed Link VLAN 20 Page Caveats and Limitations Page Page Page Page Page Basic Configuration Example MLAG Peer A MLAG Peer B MLAG Partner 962 Status Reporting Page Page Page A Complete Example Page MLAG Peer B Configuration Page MLAG Partner Configuration Cisco 3750 MLAG Partner Configuration Page Page 974 Status Reporting Spanning Tree Status Page Page Page MLAG Status Page Page Page Page Configuring Data Center Bridging Features Data Center Bridging Technology Overview 984 Default DCB Values Table29-2 lists the default val ues for the DCB features that this chapter describes. Priority Flow Control PFC Operation and Behavior no-drop drop Configuring PFC Using the Web Interface Page Configuring PFC Using the CLI NOTE: priority-id port-channel-id priority-id PFC Configuration Example Page DCB Capability Exchange Interoperability with IEEE DCBx DCBx and Port Roles Page Configuration Source Port Selection Process Disabling DCBX Configuring DCBx 998 Enhanced Transmission Selection ETS Operation Page Page Commands ETS Configuration Example Page Page Page Page Page ETS Theory of Operation Page Page Page Page Page Managing the MAC Address Table MAC Address Table Overview How Is the Address Table Populated? What Information Is in the MAC Address Table? How Is the MAC Address Table Maintained Across a Stack? Default MAC Address Table Values Managing the MAC Address Table (Web) Static Address Table . Page Global Address Table 1020 Managing the MAC Address Table (CLI) interface vlan interface vlan-id Configuring Routing Interfaces Routing Interface Overview What Are VLAN Routing Interfaces? What Are Loopback Interfaces? What Are Tunnel Interfaces? tunnel endpoint Why Are Routing Interfaces Needed? Page Default Routing Interface Values Configuring Routing Interfaces (Web) IP Interface Configuration DHCP Lease Parameters VLAN Routing Summary Tunnel Configuration Tunnels Summary Loopbacks Configuration Loopbacks Summary Configuring Routing Interfaces (CLI) Configuring VLAN Routing Interfaces (IPv4) 1034 size interface_string ip_address Configuring Loopback Interfaces Beginning in Privileged EXEC mode, use the following commands to configure a loopback interface. 1036 Configuring Tunnels ipv4addr ipv4addr Configuring DHCP Server and Relay Settings DHCP Overview How Does DHCP Work? What are DHCP Options? How is DHCP Option 82 Used? Page What Additional DHCP Features Does the Switch Support? Default DHCP Server Values Configuring the DHCP Server (Web) DHCP Server Network Properties Page Address Pool Page Page Page Address Pool Options Page DHCP Bindings DHCP Server Reset Configuration DHCP Server Conflicts Information DHCP Server Statistics Configuring the DHCP Server (CLI) Configuring Global DHCP Server Settings Configuring a Dynamic Address Pool 1056 Configuring a Static Address Pool duration duration uniqueidentifier type Monitoring DHCP Server Information DHCP Server Configuration Examples Configuring a Dynamic Address Pool Page Configuring a Static Address Pool Page Page Configuring IP Routing IP Routing Overview Page Default IP Routing Values Table33-2 shows the default values for the IP routing features this chapter describes. ARP Table Configuring IP Routing Features (Web) IP Configuration IP Statistics ARP Create ARP Table Configuration Router Discovery Configuration Router Discovery Status Route Table Best Routes Table Route Entry Configuration Page Configured Routes Route Preferences Configuration Configuring IP Routing Features (CLI) burst-size burst-interval burst-interval at support.dell.com/manuals. Adding Static ARP Entries and Configuring ARP Table Settings integer -address hardware ip-address h ardware- Configuring Router Discovery (IRDP) Beginning in Privileged EXEC mode, use the following commands to configure IRDP settings. 1082 Configuring Route Table Entries and Route Preferences nextHopRtr preference } length protocol mask protocol IP Routing Configuration Example Configuring Dell Networking Switch A Configuring Dell Networking Switch B Configuring L2 and L3 Relay Features L2 and L3 Relay Overview What Is L3 DHCP Relay? What Is L2 DHCP Relay? What Is the IP Helper Feature? Page Page 1092 Table34-2 shows the most common protocols and their UDP port numbers and names that are relayed. Default L2/L3 Relay Values Configuring L2 and L3 Relay Features (Web) DHCP Relay Global Configuration DHCP Relay Interface Configuration Page DHCP Relay Interface Statistics DHCP Relay VLAN Configuration DHCP Relay Agent Configuration Page IP Helper Global Configuration . Page IP Helper Interface Configuration Page IP Helper Statistics Configuring L2 and L3 Relay Features (CLI) range at support.dell.com/manuals. Configuring L2 DHCP Relay Page Configuring L3 Relay (IP Helper) Settings dest-udp-port server-address dest-udp-port server- server-address dest-udp-port dest-udp-port server-address Relay Agent Configuration Example Page Configuring OSPF and OSPFv3 OSPF Overview What Are OSPF Areas and Other OSPF Topology Features? What Are OSPF Routers and LSAs? How Are Routes Selected? How Are OSPF and OSPFv3 Different? OSPF Feature Details Max Metric Page Static Area Range Cost LSA Pacing Flood Blocking Page Default OSPF Values Table35-2 shows the per-interface default values for OSPF and OSPFv3. Configuring OSPF Features (Web) OSPF Configuration OSPF Area Configuration Page Page OSPF Stub Area Summary OSPF Area Range Configuration OSPF Interface Statistics OSPF Interface Configuration OSPF Neighbor Table OSPF Neighbor Configuration OSPF Link State Database OSPF Virtual Link Configuration Page OSPF Virtual Link Summary OSPF Route Redistribution Configuration OSPF Route Redistribution Summary NSF OSPF Configuration Configuring OSPFv3 Features (Web) OSPFv3 Configuration OSPFv3 Area Configuration Page Page OSPFv3 Stub Area Summary OSPFv3 Area Range Configuration OSPFv3 Interface Configuration OSPFv3 Interface Statistics OSPFv3 Neighbors OSPFv3 Neighbor Table OSPFv3 Link State Database OSPFv3 Virtual Link Configuration Page OSPFv3 Virtual Link Summary OSPFv3 Route Redistribution Configuration OSPFv3 Route Redistribution Summary NSF OSPFv3 Configuration Configuring OSPF Features (CLI) Configuring Global OSPF Settings Page delay-time hold-time delay-time neighbor-id vlan-id hold-time Configuring OSPF Interface Settings number- number-value key key-id interface- bw bw interface-cost Configuring Stub Areas and NSSAs ip-address wildcard-mask vlan-id wildcard-mask Page 1162 Configuring Virtual Links router-id neighbor-id area-id Beginning in Privileged EXEC mode, use the following commands to configure OSPF Virtual Links. Page 1164 Configuring OSPF Area Range Settings ip-address mask Beginning in Privileged EXEC mode, use the following commands to configure an OSPF area range. Configuring OSPF Route Redistribution Settings accesslistname accesslistname tag 1166 Configuring NSF Settings for OSPF Configuring OSPFv3 Features (CLI) type-value ref_bw Dell Networking N2000, N3000, and N4000 Series Switches CLI Reference Guide at support.dell.com/manuals. distance maxpaths Configuring OSPFv3 Interface Settings Page Configuring Stub Areas and NSSAs metric-type- metric-value metric-type-value role Configuring Virtual Links Beginning in Privileged EXEC mode, use the following commands to configure OSPFv3 Virtual Links. 1174 Configuring an OSPFv3 Area Range ipv6-prefix/prefix-length Beginning in Privileged EXEC mode, use the following commands to configure an OSPFv3 area range. prefix/prefix-length Configuring OSPFv3 Route Redistribution Settings tag tag metric 1176 Configuring NSF Settings for OSPFv3 OSPF Configuration Examples Configuring an OSPF Border Router and Setting Interface Costs Page Page Configuring Stub and NSSA Areas for OSPF and OSPFv3 Page Page Page Configuring a Virtual Link for OSPF and OSPFv3 Page Page Interconnecting an IPv4 Backbone and Local IPv6 Network Page Page Configuring the Static Area Range Cost 2 Configure R1. 1192 3 Configure R2. R3 config: 1194 Discussion With no area range cost specified, the range uses auto cost: Configuring Flood Blocking 1196 2 Configure R1: 3 Configure R2: 1198 Configure R3: Page Page Configuring RIP RIP Overview How Does RIP Determine Route Information? What Is Split Horizon? What RIP Versions Are Supported? Default RIP Values Configuring RIP Features (Web) RIP Configuration RIP Interface Configuration RIP Interface Summary RIP Route Redistribution Configuration RIP Route Redistribution Summary Configuring RIP Features (CLI) at support.dell.com/manuals. Configuring Global RIP Settings metric- 1210 Configuring RIP Interface Settings key key-id Configuring Route Redistribution Settings accesslistname accesslistname Page RIP Configuration Example 1214 Enable auto summarization of subprefixes when crossing classful boundaries. 5 Verify the configuration Page Page Configuring VRRP VRRP Overview How Does VRRP Work? What Is the VRRP Router Priority? What Is VRRP Preemption? What Is VRRP Accept Mode? What Are VRRP Route and Interface Tracking? Page Default VRRP Values Table37-1 shows the global default values for VRRP. Configuring VRRP Features (Web) VRRP Configuration VRRP Virtual Router Status VRRP Virtual Router Statistics VRRP Router Configuration VRRP Route Tracking Configuration Page VRRP Interface Tracking Configuration Page 1230 Configuring VRRP Features (CLI) at support.dell.com/manuals. Configuring VRRP Settings priority ip-address/prefix-leng th priority ip-address/prefix-length vlan-id VRRP Configuration Example VRRP with Load Sharing Page Page Troubleshooting VRRP VRRP with Route and Interface Tracking Page Page Page Page Configuring IPv6 Routing IPv6 Routing Overview How Does IPv6 Compare with IPv4? How Are IPv6 Interfaces Configured? Default IPv6 Routing Values 1244 Table38-2 shows the default IPv6 interface values after a VLAN routing interface has been created. Configuring IPv6 Routing Features (Web) Global Configuration Interface Configuration Interface Summary IPv6 Statistics IPv6 Neighbor Table DHCPv6 Client Parameters DHCPv6 Client Statistics IPv6 Router Entry Configuration IPv6 Route Table IPv6 Route Preferences Configured IPv6 Routes 1256 Configuring IPv6 Routing Features (CLI) burst-size burst-interval burst-interval at support.dell.com/manuals. Configuring IPv6 Interface Settings prefix/prefix-length ACL 1258 Configuring IPv6 Neighbor Discovery value seconds minimum maximum milliseconds other stateful configuration milliseconds managed address configuration 1260 Configuring IPv6 Route Table Entries and Route Preferences prefix-length prefix next-hop-address interface-type interface-number Page 1262 IPv6 Show Commands interface-type interface-number ipv6-prefix/ prefix-length protocol ipv6-address IPv6 Static Reject and Discard Routes Page Configuring DHCPv6 Server and Relay Settings DHCPv6 Overview What Is a DHCPv6 Pool? What Is a Stateless Server? other stateful configuration stateless What Is the DHCPv6 Relay Agent Information Option? Default DHCPv6 Server and Relay Values Configuring the DHCPv6 Server and Relay (Web) DHCPv6 Global Configuration DHCPv6 Pool Configuration Page Prefix Delegation Configuration DHCPv6 Pool Summary DHCPv6 Interface Configuration Page DHCPv6 Server Bindings Summary DHCPv6 Statistics Configuring the DHCPv6 Server and Relay (CLI) Configuring Global DHCP Server and Relay Agent Settings Configuring a DHCPv6 Pool for Stateless Server Support 1278 domain Configuring a DHCPv6 Pool for Specific Hosts prefix/prefix-length client-DUID preferred- lifetime Configuring DHCPv6 Interface Information user-defined-string relay-address relay- user- defined-string Monitoring DHCPv6 Information pool- pref-value pool-name pref-value DHCPv6 Configuration Examples Configuring a DHCPv6 Stateless Server Configuring the DHCPv6 Server for Prefix Delegation Configuring an Interface as a DHCPv6 Relay Agent Page Configuring Differentiated Services DiffServ Overview How Does DiffServ Functionality Vary Based on the Role of the Switch? What Are the Elements of DiffServ Configuration? Default DiffServ Values Configuring DiffServ (Web) DiffServ Configuration Class Configuration Class Criteria Page Policy Configuration Page Policy Class Definition Page Page Service Configuration Service Detailed Statistics Flow-Based Mirroring Configuring DiffServ (CLI) DiffServ Configuration (Global) DiffServ Class Configuration for IPv4 Page 1302 DiffServ Class Configuration for IPv6 class-map- name DiffServ Policy Creation policy-name 1304 DiffServ Policy Attributes Configuration dscpval cos burstsize datarate Page 1306 DiffServ Service Configuration DiffServ Configuration Examples Providing Subnets Equal Access to External Network all internet_access, Page DiffServ for VoIP class_voip match-all Page Configuring Class-of-Service CoS Overview What Are Trusted and Untrusted Port Modes? How Is Traffic Shaping Used on Egress Traffic? How Are Traffic Queues Defined? Which Queue Management Methods Are Supported? CoS Queue Usage Default CoS Values Page Configuring CoS (Web) Mapping Table Configuration Page Interface Configuration Interface Queue Configuration Interface Queue Drop Precedence Configuration Page 1324 Configuring CoS (CLI) port-channel number at support.dell.com/manuals. Mapping Table Configuration CoS Interface Configuration Commands Interface Queue Configuration 1326 Configuring Interface Queue Drop Probability CoS Configuration Example Page Page Configuring Auto VoIP Auto VoIP Overview How Does Auto-VoIP Use ACLs? Default Auto VoIP Values Configuring Auto VoIP (Web) Auto VoIP Global Configuration Auto VoIP Interface Configuration Page Configuring Auto VoIP (CLI) Page Managing IPv4 and IPv6 Multicast L3 Multicast Overview What Is IP Multicast Traffic? What Multicast Protocols Does the Switch Support? What Are the Multicast Protocol Roles? When Is L3 Multicast Required on the Switch? What Is the Multicast Routing Table? What Is IGMP? What Is MLD? What Is PIM? Page Page Page Page Page Page Page Page Page What Is DVMRP? Prune messages Page Default L3 Multicast Values Page Configuring General IPv4 Multicast Features (Web) Multicast Global Configuration Multicast Interface Configuration Multicast Route Table Multicast Admin Boundary Configuration Multicast Admin Boundary Summary Multicast Static MRoute Configuration Multicast Static MRoute Summary Configuring IPv6 Multicast Features (Web) IPv6 Multicast Route Table Configuring IGMP and IGMP Proxy (Web) IGMP Global Configuration IGMP Interface Configuration IGMP Interface Summary IGMP Cache Information Page IGMP Interface Source List Information IGMP Proxy Interface Configuration IGMP Proxy Configuration Summary IGMP Proxy Interface Membership Info Detailed IGMP Proxy Interface Membership Information Configuring MLD and MLD Proxy (Web) MLD Global Configuration MLD Routing Interface Configuration MLD Routing Interface Summary MLD Routing Interface Cache Information MLD Routing Interface Source List Information MLD Traffic MLD Proxy Configuration MLD Proxy Configuration Summary MLD Proxy Interface Membership Inform ation Detailed MLD Proxy Interface Membership Information Configuring PIM for IPv4 and IPv6 (Web) PIM Global Configuration PIM Global Status PIM Interface Configuration PIM Interface Summary Candidate RP Configuration Page Static RP Configuration Page SSM Range Configuration Page BSR Candidate Configuration BSR Candidate Summary Configuring DVMRP (Web) DVMRP Global Configuration DVMRP Interface Configuration DVMRP Configuration Summary DVMRP Next Hop Summary DVMRP Prune Summary DVMRP Route Summary Configuring L3 Multicast Features (CLI) ttlvalue groupipaddr mask mask source-address Page Configuring and Viewing IPv6 Multicast Route Information sourceipaddr source-address/prefix-length preference source- address/prefix-length rpf- address Configuring and Viewing IGMP count tenthsofseconds count 1404 Configuring and Viewing IGMP Proxy Configuring and Viewing MLD count tenthsofseconds seconds version Configuring and Viewing MLD Proxy NOTE: Configuring and Viewing PIM-DM for IPv4 Multicast Routing 1408 Configuring and Viewing PIM-DM for IPv6 Multicast Routing Page 1410 Configuring and Viewing PIM-SM for IPv4 Multicast Routing interval hash-mask-length interval vlan-id hash-mask-length vlan-id group-address group- mask interval group-address group-mask group-mask group-address Configuring and Viewing PIM-SM for IPv6 Multicast Routing vlan-id hash-mask-length interval group-address/prefix-length interval interval group-address/prefix-length group-address/prefix-length groupaddr 1416 Configuring and Viewing DVMRP Information metric L3 Multicast Configuration Examples Configuring Multicast VLAN Routing With IGMP and PIM-SM Page Page Page Configuring DVMRP Page A Feature Limitations and Platform Constants Page Page Page Page Page Page Page Page Page B System Process Definitions Page Page Page Page Page Page Page Index Numerics A B C Page D E F G H I Page J L M Page N O P Q R S Page T U V W