Cisco 2950G 24 - Catalyst Switch - Displaying UDLD Status

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Catalyst 2950 Desktop Switch Software Configuration Guide

78-14982-01

Chapter 19 Configuring UDLD

Displaying UDLD Status

To display the UDLD status for the specified interface or for all interfaces, use the show udld

[interface-id] privileged EXEC command.

For detailed information about the fields in the display, refer to the command reference for this release.

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Default Chapter4
- Table of Contents4
Chapter 2 Using the Command-Line Interface26
- Related Publications29
- Obtaining Documentation29
- World Wide Web29
- Ordering Documentation30
- Documentation Feedback30
- Obtaining Technical Assistance30
- Management Options39
- Management Interface Options39
- Advantages of Using Cms and Clustering Switches39
- Network Configuration Examples40
- Design Concepts for Using the Switch40
- Collapsed Backbone and Switch Cluster Configuration45
- Large Campus Configuration46
- Hotel Network Configuration48
- Multidwelling Network Using Catalyst 2950 Switches50
- Where to Go Next53
- IOS Command Modes55
Getting Help57
- Specifying Ports in Interface Configuration Mode58
Abbreviating Commands59
Using no and Default Forms of Commands59
Understanding CLI Messages59
Using Command History60
- Changing the Command History Buffer Size60
- Recalling Commands60
- Disabling the Command History Feature61
Using Editing Features61
- Enabling and Disabling Editing Features61
- Editing Commands through Keystrokes62
- Editing Command Lines that Wrap63
Searching and Filtering Output of Show and more Commands64
Accessing the CLI64
- Accessing the CLI from a Browser65
Chapter 3 Getting Started with CM68
Features68
Front Panel View70
- Cluster Tree72
- Front-Panel Images73
Topology View76
- Topology Icons78
- Device and Link Labels79
- Colors in the Topology View80
- Topology Display Options81
Menus and Toolbar81
- Menu Bar81
- Toolbar86
- Front Panel View Popup Menus87
  - Device Popup Menu87
  - Port Popup Menu87
- Topology View Popup Menus88
  - Link Popup Menu88
  - Device Popup Menus89
Interaction Modes91
- Guide Mode91
- Expert Mode91
Wizards92
- Tool Tips92
Online Help92
CMS Window Components94
- Host Name List94
- Tabs, Lists, and Tables95
  - Filter Editor95
- Icons Used in Windows95
- Buttons96
Accessing CMS96
- Access Modes in CMS97
- HTTP Access to CMS98
Verifying Your Changes98
- Change Notification98
- Error Checking98
Saving Your Configuration99
Restoring Your Configuration99
CMS Preferences99
Using Different Versions of CMS100
Where to Go Next100
Chapter 4 Assigning the Switch IP Address and Default Gateway101
- Understanding the Boot Process101
- Assigning Switch Information102
- Checking and Saving the Running Configuration110
Chapter 5 Configuring IE2100 CNS Agents113
- Understanding IE2100 Series Configuration Registrar Software113
- Understanding CNS Embedded Agents117
- Configuring CNS Embedded Agents118
- Displaying CNS Configuration125
Chapter 6 Clustering Switches127
- Understanding Switch Clusters128
- Planning a Switch Cluster131
- TACACS+ and RADIUS143
- Access Modes in CMS143
- Management VLAN144
- LRE Profiles144
- Availability of Switch-Specific Features in Switch Clusters145
Chapter 7 Administering the Switch154
- Protecting Access to Privileged EXEC Commands154
- Controlling Switch Access with TACACS162
- Controlling Switch Access with RADIUS170
- Configuring RADIUS Login Authentication175
- Defining AAA Server Groups177
- Configuring RADIUS Authorization for User Privileged Access and Network Services179
- Starting RADIUS Accounting180
- Configuring Settings for All RADIUS Servers181
- Configuring the Switch to Use Vendor-Specific RADIUS Attributes181
- Configuring the Switch for Vendor-Proprietary RADIUS Server Communication182
- Default NTP Configuration189
- Configuring NTP Authentication189
- Configuring NTP Associations190
- Configuring NTP Broadcast Service191
- Configuring NTP Access Restrictions192
- Configuring the Source IP Address for NTP Packets194
- Displaying the NTP Configuration195
CHAPTER 8 Configuring 802.1X Port-Based Authentication215
- Understanding 802.1X Port-Based Authentication215
- Configuring 802.1X Authentication219
  - Default 802.1X Configuration220
- 802.1X Configuration Guidelines221
- Enabling 802.1X Authentication222
- Configuring the Switch-To-RADIUS-Server Communication223
- Enabling Periodic Re-Authentication224
- Manually Re-Authenticating a Client Connected to a Port225
- Changing the Quiet Period225
- Changing the Switch-To-Client Retransmission Time226
- Setting the Switch-To-Client Frame-Retransmission Number227
  - Displaying 802.1X Statistics and Status228
- Enabling Multiple Hosts227
- Resetting the 802.1X Configuration to the Default Values228
Chapter 9 Configuring the Switch Interfaces229
- Understanding Interface Types229
- Using the Interface Command232
- Configuring Switch Interfaces237
- Default Ethernet Interface Configuration238
- SFP Configuration238
- Configuring Interface Speed and Duplex Mode239
  - Configuration Guidelines240
  - Setting the Interface Speed and Duplex Parameters241
- Configuring Media Types for Gigabit Interfaces242
- Configuring IEEE 802.3X Flow Control on Gigabit Ethernet Ports242
- Adding a Description for an Interface244
  - Monitoring and Maintaining the Interfaces244
Chapter 10 Configuring LRE249
- Ports on the 2950 LRE249
- LRE Links and LRE Profiles250
- Configuring LRE Ports253
- Environmental Guidelines for LRE Links254
- Guidelines for Using LRE Profiles255
- CPE Ethernet Link Guidelines255
  - Considerations for Connected Cisco 575 LRE Cpes255
  - Considerations for Connected Cisco 585 LRE Cpes255
- Assigning a Global Profile to All LRE Ports256
  - Assigning a Global Sequence to All LRE Ports257
- Assigning a Profile to a Specific LRE Port257
  - Assigning a Sequence to a Specific LRE Port258
- Using Rate Selection to Automatically Assign Profiles258
- LRE Link Persistence262
  - Upgrading LRE Switch Firmware263
- LRE Link Monitor262
Understanding Spanning-Tree Features269
- Configuring STP270
- Understanding Spanning-Tree Features270
Chapter 11 Configuring STP270
- STP Overview270
- Supported Spanning-Tree Instances270
- Bridge Protocol Data Units270
- Election of the Root Switch271
  - Bridge ID, Switch Priority, and Extended System ID272
  - Spanning-Tree Timers272
- Creating the Spanning-Tree Topology273
- Spanning-Tree Interface States273
- Spanning-Tree Address Management276
- STP and IEEE 802.1Q Trunks276
Chapter 12 Configuring RSTP and MSTP291
- Understanding RSTP292
- Understanding MSTP297
  - Multiple Spanning-Tree Regions297
  - IST, CIST, and CST298
    - Operations Within an MST Region298
    - Operations between MST Regions299
- Hop Count300
CHAPTER 13 Configuring Optional Spanning-Tree Features316
- Understanding Optional Spanning-Tree Features316
- Configuring Optional Spanning-Tree Features326
- Default Optional Spanning-Tree Configuration328
- Enabling Port Fast328
- Enabling BPDU Guard329
- Enabling BPDU Filtering330
- Enabling Uplinkfast for Use with Redundant Links331
- Enabling Cross-Stack Uplinkfast332
- Enabling Backbonefast333
- Enabling Root Guard333
- Enabling Loop Guard334
  - Displaying the Spanning-Tree Status335
  - Understanding Vlans337
Chapter 14 Configuring VLAN338
- Supported Vlans338
- VLAN Port Membership Modes339
- Configuring Normal-Range Vlans340
- Configuring Extended-Range Vlans348
- Displaying Vlans350
- Configuring VLAN Trunks351
- Configuring VMPS360
- Configuring VTP370
- Understanding VTP370
Chapter 15 Configuring VTP370
- The VTP Domain370
- VTP Modes371
- VTP Advertisements371
- VTP Version 2372
- VTP Pruning372
- Configuring VTP372
- Monitoring VTP384
Chapter 16 Configuring Voice VLAN385
- Understanding Voice VLAN385
- Configuring Voice VLAN386
- Displaying Voice VLAN390
- Understanding IGMP Snooping391
Chapter 17 Configuring IGMP Snooping and MVR392
- Joining a Multicast Group392
- Leaving a Multicast Group394
- Immediate-Leave Processing394
- Configuring IGMP Snooping395
- Displaying IGMP Snooping Information401
- Understanding Multicast VLAN Registration403
  - Using MVR in a Multicast Television Application403
- Configuring MVR405
- Displaying MVR Information409
- Configuring IGMP Filtering410
- Displaying IGMP Filtering Configuration414
CHAPTER 18 Configuring Port-Based Traffic Control415
- Configuring Storm Control415
- Configuring Protected Ports417
- Configuring Port Security418
- Displaying Port-Based Traffic Control Settings426
Chapter 19 Configuring UDLD427
- Understanding UDLD427
- Configuring UDLD427
- Displaying UDLD Status432
Chapter 20 Configuring CDP433
- Understanding CDP433
- Configuring CDP434
- Monitoring and Maintaining CDP437
Chapter 21 Configuring SPAN and RSPAN439
- Understanding SPAN and RSPAN439
- Configuring SPAN446
- Configuring RSPAN452
- Displaying SPAN and RSPAN Status458
Chapter 22 Configuring RMON459
- Understanding RMON459
- Configuring RMON460
- Displaying RMON Status464
Chapter 23 Configuring System Message Logging465
- Understanding System Message Logging465
- Configuring System Message Logging466
- Displaying the Logging Configuration476
Chapter 24 Configuring SNMP477
- Understanding SNMP477
- Configuring SNMP481
- Displaying SNMP Status491
Chapter 25 Configuring Network Security with Acls493
- Understanding Acls494
- Configuring Acls498
- Applying Acls to Terminal Lines or Physical Interfaces512
  - Applying Acls to a Terminal Line512
  - Applying Acls to a Physical Interface513
- Displaying ACL Information513
  - Displaying Acls514
  - Displaying Access Groups515
- Examples for Compiling Acls515
Chapter 26 Configuring Qos519
- Understanding Qos520
- Configuring Qos527
- Displaying Qos Information546
- Qos Configuration Examples547
  - Qos Configuration for the Existing Wiring Closet548
  - Qos Configuration for the Intelligent Wiring Closet548
Chapter 27 Configuring Etherchannels551
- Understanding Etherchannels551
- Configuring Etherchannels557
- Displaying Etherchannel and Pagp Status561
Chapter 28 Troubleshooting563
- LRE Statistics563
- Using Recovery Procedures568
- Preventing Autonegotiation Mismatches574
- Troubleshooting LRE Port Configuration574
- GBIC and SFP Module Security and Identification575
- Using Debug Commands576
- Using the Crashinfo File577
Appendix579
Supported Mibs579
- MIB List579
- Using FTP to Access the MIB Files580
Appendix A Supported MIB580
Appendix583
Working with the IOS File System, Configuration Files, and Software Images583
- Working with the Flash File System583
- Working with Configuration Files590
- Working with Software Images602
I N D E X617

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