Cisco 2950 - Catalyst Switch User manual

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Catalyst 2950 Desktop Switch Software
Configuration Guide
Cisco IOS Release 12.1(9)EA1
April 2002
Customer Order Number: DOC-7811380=
Text Part Number: 78-11380-04

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Catalyst 2950 Desktop Switch Software Configuration Guide
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CONTENTS
Preface xxi
Audience xxi
Purpose xxi
Organization xxii
Conventions xxiv
Related Publications xxv
Obtaining Documentation xxv
World Wide Web xxv
Documentation CD-ROM xxv
Ordering Documentation xxvi
Documentation Feedback xxvi
Obtaining Technical Assistance xxvi
Cisco.com xxvi
Technical Assistance Center xxvii
Cisco TAC Website xxvii
Cisco TAC Escalation Center xxviii
CHAPTER 1Overview 1-1
Features 1-1
ManagementOptions 1-6
ManagementInterface Options 1-6
Advantages of Using CMS and Clustering Switches 1-7
Network Configuration Examples 1-8
Design Concepts for Using the Switch 1-8
Small to Medium-Sized Network Configuration 1-10
Collapsed Backbone and Switch Cluster Configuration 1-12
Large Campus Configuration 1-13
Multidwelling Network Using Catalyst 2950 Switches 1-14
Long-Distance, High-Bandwidth Transport Configuration 1-16
CHAPTER 2Using the Command-Line Interface 2-1
IOS Command Modes 2-1
Getting Help 2-3

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Abbreviating Commands 2-3
Using no and default Forms ofCommands 2-4
Understanding CLI Messages 2-4
Using Command History 2-5
Changing the Command History Buffer Size 2-5
Recalling Commands 2-5
Disabling the Command History Feature 2-5
Using Editing Features 2-6
Enabling and Disabling Editing Features 2-6
Editing Commands through Keystrokes 2-6
Editing Command Lines that Wrap 2-7
Searching and Filtering Output of show and more Commands 2-8
Accessing the CLI 2-9
Accessing the CLI from a Browser 2-9
Saving Configuration Changes 2-10
Where to Go Next 2-10
CHAPTER 3Getting Started with CMS 3-1
Features 3-2
Front Panel View 3-4
Cluster Tree 3-5
Front-PanelImages 3-6
Redundant Power System LED 3-7
Port Modes and LEDs 3-8
VLAN Membership Modes 3-9
Topology View 3-9
Topology Icons 3-11
Device and Link Labels 3-12
Colors in the Topology View 3-13
Topology Display Options 3-13
Menus and Toolbar 3-14
Menu Bar 3-14
Toolbar 3-20
Front Panel View Popup Menus 3-21
Device Popup Menu 3-21
Port Popup Menu 3-21

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Topology View Popup Menus 3-22
Link Popup Menu 3-22
Device Popup Menus 3-23
Interaction Modes 3-25
Guide Mode 3-25
Expert Mode 3-25
Wizards 3-25
ToolTips 3-26
Online Help 3-26
CMS Window Components 3-27
Host Name List 3-27
Tabs, Lists, and Tables 3-28
Icons Used in Windows 3-28
Buttons 3-28
Accessing CMS 3-29
Access Modes in CMS 3-30
HTTP Access to CMS 3-30
Verifying Your Changes 3-31
Change Notification 3-31
Error Checking 3-31
Saving Your Changes 3-31
UsingDifferent Versions of CMS 3-32
Where to Go Next 3-32
CHAPTER 4Assigning the Switch IP Address and Default Gateway 4-1
Understanding the Boot Process 4-1
Assigning Switch Information 4-2
Default Switch Information 4-3
Understanding DHCP-Based Autoconfiguration 4-3
DHCP Client Request Process 4-3
Configuring the DHCP Server 4-5
Configuring the TFTP Server 4-5
Configuring the DNS 4-6
Configuring the Relay Device 4-6
Obtaining Configuration Files 4-7
Example Configuration 4-8
Manually Assigning IP Information 4-10
Checking and Saving the Running Configuration 4-11

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CHAPTER 5Configuring IE2100 CNS Agents 5-1
Understanding IE2100 Series Configuration Registrar Software 5-1
CNS Configuration Service 5-2
CNS Event Service 5-3
NameSpace Mapper 5-3
What You Should Know About ConfigID, DeviceID, and Host Name 5-3
ConfigID 5-3
DeviceID 5-4
Host Name and DeviceID 5-4
Using Host Name, DeviceID, and ConfigID 5-4
Understanding CNS Embedded Agents 5-5
Initial Configuration 5-5
Incremental (Partial) Configuration 5-6
Synchronized Configuration 5-6
Configuring CNS Embedded Agents 5-6
Enabling Automated CNS Configuration 5-6
Enabling the CNS Event Agent 5-8
Enabling the CNS Configuration Agent 5-9
Enabling an Initial Configuration 5-9
Enabling a Partial Configuration 5-12
Displaying CNS Configuration 5-12
CHAPTER 6Clustering Switches 6-1
Understanding Switch Clusters 6-2
Command Switch Characteristics 6-3
Standby Command Switch Characteristics 6-3
Candidate Switch and Member Switch Characteristics 6-4
Planning a Switch Cluster 6-5
Automatic Discovery of Cluster Candidates and Members 6-5
Discovery through CDP Hops 6-6
Discovery through Non-CDP-Capable and Noncluster-Capable Devices 6-8
Discovery through the Same Management VLAN 6-9
Discovery through Different Management VLANs 6-10
Discovery of Newly Installed Switches 6-12
HSRP and Standby Command Switches 6-14
Virtual IP Addresses 6-15
Other Considerations for Cluster Standby Groups 6-15
Automatic Recovery of Cluster Configuration 6-17

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IP Addresses 6-17
Host Names 6-18
Passwords 6-18
SNMP Community Strings 6-18
TACACS+ and RADIUS 6-19
Access Modes in CMS 6-19
ManagementVLAN 6-20
LRE Profiles 6-20
Availability of Switch-Specific Features in Switch Clusters 6-21
Creating a Switch Cluster 6-21
Enabling a Command Switch 6-22
Adding Member Switches 6-23
Creating a Cluster Standby Group 6-25
Verifying a Switch Cluster 6-27
Using the CLI to Manage Switch Clusters 6-28
Catalyst 1900 and Catalyst 2820 CLI Considerations 6-28
Using SNMP to Manage Switch Clusters 6-29
CHAPTER 7Administering the Switch 7-1
Preventing Unauthorized Access to Your Switch 7-1
Protecting Access to Privileged EXEC Commands 7-2
Default Password and Privilege Level Configuration 7-3
Setting or Changing a Static Enable Password 7-3
Protecting Enable and Enable Secret Passwords with Encryption 7-4
Setting a Telnet Password for a Terminal Line 7-5
Configuring Username and Password Pairs 7-6
Configuring Multiple Privilege Levels 7-7
Setting the Privilege Level for a Command 7-7
Changing the Default Privilege Level for Lines 7-8
Logging into and Exiting a Privilege Level 7-9
Controlling Switch Access with TACACS+ 7-9
Understanding TACACS+ 7-9
TACACS+ Operation 7-11
Configuring TACACS+ 7-12
Default TACACS+ Configuration 7-12
Identifying the TACACS+ Server Host and Setting the Authentication Key 7-12
Configuring TACACS+ Login Authentication 7-13
Configuring TACACS+ Authorization for Privileged EXEC Access and Network Services 7-15
Starting TACACS+ Accounting 7-16

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Displaying the TACACS+ Configuration 7-16
Controlling Switch Access with RADIUS 7-17
Understanding RADIUS 7-17
RADIUS Operation 7-18
Configuring RADIUS 7-19
Default RADIUS Configuration 7-19
Identifying the RADIUS Server Host 7-20
Configuring RADIUS Login Authentication 7-22
Defining AAA Server Groups 7-24
Configuring RADIUS Authorization for Privileged EXEC Access and Network Services 7-26
Starting RADIUS Accounting 7-27
Configuring Settings for All RADIUS Servers 7-28
Configuring the Switch to Use Vendor-Specific RADIUS Attributes 7-28
Configuring the Switch for Vendor-Proprietary RADIUS Server Communication 7-29
Displaying the RADIUS Configuration 7-30
Configuring the Switch for Local Authentication and Authorization 7-31
Configuring the Switch for Secure Shell 7-32
Understanding SSH 7-32
Configuring SSH 7-32
Managing the System Time and Date 7-33
Understanding the System Clock 7-33
Understanding Network Time Protocol 7-33
Configuring NTP 7-35
Default NTP Configuration 7-36
Configuring NTP Authentication 7-36
Configuring NTP Associations 7-37
Configuring NTP Broadcast Service 7-38
Configuring NTP Access Restrictions 7-39
Configuring the Source IP Address for NTP Packets 7-41
Displaying the NTP Configuration 7-42
Configuring Time and Date Manually 7-42
Setting the System Clock 7-43
Displaying the Time and Date Configuration 7-43
Configuring the TimeZone 7-44
Configuring Summer Time (Daylight Saving Time) 7-45
Configuring a System Nameand Prompt 7-47
Default System Name and Prompt Configuration 7-47
Configuring a System Name 7-47
Configuring a System Prompt 7-48

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Understanding DNS 7-48
Default DNS Configuration 7-49
Setting Up DNS 7-49
Displaying the DNS Configuration 7-50
Creating a Banner 7-50
Default BannerConfiguration 7-50
Configuring a Message-of-the-Day Login Banner 7-50
Configuring a Login Banner 7-52
Managing the MAC Address Table 7-52
Building the Address Table 7-53
MAC Addresses and VLANs 7-53
Default MAC Address Table Configuration 7-54
Changing the Address Aging Time 7-54
Removing Dynamic Address Entries 7-55
Configuring MAC AddressNotification Traps 7-55
Adding and Removing Static Address Entries 7-57
Configuring Static Addresses for EtherChannel Port Groups 7-58
Adding and Removing Secure Addresses 7-58
Displaying Address Table Entries 7-59
Managing the ARP Table 7-59
CHAPTER 8Configuring 802.1X Port-Based Authentication 8-1
Understanding 802.1X Port-Based Authentication 8-1
Device Roles 8-2
Authentication Initiation and Message Exchange 8-3
Ports in Authorized and Unauthorized States 8-4
Supported Topologies 8-5
Configuring 802.1X Authentication 8-6
Default 802.1X Configuration 8-6
802.1X Configuration Guidelines 8-7
Enabling 802.1X Authentication 8-8
Configuring the Switch-to-RADIUS-ServerCommunication 8-9
Enabling Periodic Re-Authentication 8-10
Manually Re-Authenticating a Client Connected to a Port 8-11
Changing the Quiet Period 8-11
Changing the Switch-to-Client Retransmission Time 8-12
Setting the Switch-to-Client Frame-Retransmission Number 8-13
Enabling Multiple Hosts 8-13

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Resetting the 802.1X Configuration to the Default Values 8-14
Displaying 802.1X Statisticsand Status 8-14
CHAPTER 9Configuring Interface Characteristics 9-1
Understanding Interface Types 9-1
Port-Based VLANs 9-1
Switch Ports 9-2
Access Ports 9-2
Trunk Ports 9-2
EtherChannelPort Groups 9-3
Connecting Interfaces 9-3
Using the Interface Command 9-4
Procedures for Configuring Interfaces 9-5
Configuring a Range of Interfaces 9-7
Configuring and Using Interface Range Macros 9-9
Configuring Layer 2 Interfaces 9-10
Default Layer 2 EthernetInterface Configuration 9-11
Configuring the Port Speed and Duplex Mode 9-11
Configuration Guidelines 9-12
Connecting to Devices That Do Not Autonegotiate 9-12
Setting Speed and Duplex Parameters 9-12
Configuring IEEE 802.3X Flow Control on Gigabit Ethernet Ports 9-14
Adding a Description foran Interface 9-15
Monitoring and Maintaining the Interface 9-16
Monitoring Interface and ControllerStatus 9-16
Clearing and Resetting Interfaces and Counters 9-18
Shutting Down and Restarting the Interface 9-19
CHAPTER 10 Configuring STP 10-1
Understanding Spanning-Tree Features 10-1
STP Overview 10-2
Supported Spanning-Tree Instances 10-2
Bridge ProtocolData Units 10-2
Election of the Root Switch 10-3
Bridge ID, Switch Priority, and Extended System ID 10-4
Spanning-Tree Timers 10-4
Creating the Spanning-Tree Topology 10-5

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Spanning-Tree Interface States 10-5
Blocking State 10-7
Listening State 10-7
Learning State 10-7
Forwarding State 10-7
Disabled State 10-8
Spanning-Tree Address Management 10-8
STP and IEEE 802.1Q Trunks 10-8
Spanning Tree and Redundant Connectivity 10-8
Accelerated Aging to Retain Connectivity 10-9
Configuring Spanning-Tree Features 10-9
Default STP Configuration 10-10
STP Configuration Guidelines 10-10
Disabling STP 10-11
Configuring the Root Switch 10-12
Configuring a Secondary Root Switch 10-13
Configuring the Port Priority 10-14
Configuring the Path Cost 10-15
Configuring the Switch Priority of a VLAN 10-17
Configuring the Hello Time 10-18
Configuring the Forwarding-Delay Time fora VLAN 10-18
Configuring the Maximum-Aging Time for a VLAN 10-19
Configuring STP for Use in a Cascaded Stack 10-20
Displaying Spanning-Tree Status 10-21
CHAPTER 11 Configuring RSTP and MSTP 11-1
Understanding RSTP 11-2
Port Roles and the Active Topology 11-2
Rapid Convergence 11-3
Synchronization of Port Roles 11-4
Bridge ProtocolData Unit Format and Processing 11-5
Processing Superior BPDU Information 11-6
Processing Inferior BPDU Information 11-6
Topology Changes 11-6
Understanding MSTP 11-7
Multiple Spanning-Tree Regions 11-7
IST, CIST, and CST 11-8
Operations Within an MST Region 11-8
Operations Between MST Regions 11-9

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Hop Count 11-10
Boundary Ports 11-10
Interoperability with 802.1D STP 11-10
Configuring RSTP and MSTP Features 11-11
Default RSTP and MSTP Configuration 11-12
RSTP and MSTP Configuration Guidelines 11-12
Specifying the MST Region Configuration and Enabling MSTP 11-13
Configuring the Root Switch 11-14
Configuring a Secondary Root Switch 11-16
Configuring the Port Priority 11-17
Configuring the Path Cost 11-18
Configuring the Switch Priority 11-19
Configuring the Hello Time 11-19
Configuring the Forwarding-Delay Time 11-20
Configuring the Maximum-Aging Time 11-21
Configuring the Maximum-Hop Count 11-21
Specifying the Link Type to Ensure Rapid Transitions 11-22
Restarting the Protocol Migration Process 11-22
Displaying the MST Configuration and Status 11-23
CHAPTER 12 Configuring Optional Spanning-Tree Features 12-1
Understanding Optional Spanning-Tree Features 12-1
Understanding Port Fast 12-2
Understanding BPDU Guard 12-3
Understanding BPDU Filtering 12-3
Understanding UplinkFast 12-4
Understanding Cross-Stack UplinkFast 12-5
How CSUF Works 12-6
Events that Cause Fast Convergence 12-7
Limitations 12-8
Connecting the Stack Ports 12-8
Understanding BackboneFast 12-10
Understanding Root Guard 12-12
Understanding Loop Guard 12-13
Configuring OptionalSpanning-TreeFeatures 12-13
Default OptionalSpanning-Tree Configuration 12-14
Enabling Port Fast 12-14
Enabling BPDU Guard 12-15
Enabling BPDU Filtering 12-16

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Enabling UplinkFast for Use with Redundant Links 12-17
Enabling Cross-Stack UplinkFast 12-18
Enabling BackboneFast 12-19
Enabling Root Guard 12-19
Enabling Loop Guard 12-20
Displaying the Spanning-Tree Status 12-21
CHAPTER 13 Configuring VLANs 13-1
Understanding VLANs 13-1
Supported VLANs 13-2
ManagementVLANs 13-3
Determining the Management VLAN for a New Switch 13-4
Changing the Management VLAN fora Cluster 13-4
VLAN Port Membership Modes 13-5
Configuring Normal-RangeVLANs 13-6
Token Ring VLANs 13-7
ConfigurationGuidelines forNormal-Range VLANs 13-7
VLAN Configuration Mode Options 13-8
VLAN Configuration in config-vlan Mode 13-8
VLAN Configuration in VLAN Configuration Mode 13-8
Saving VLAN Configuration 13-9
Default Ethernet VLAN Configuration 13-10
Creating or Modifying an Ethernet VLAN 13-10
Deleting a VLAN 13-12
Assigning Static-Access Ports to a VLAN 13-13
Configuring Extended-Range VLANs 13-14
Default VLAN Configuration 13-14
ConfigurationGuidelines forExtended-Range VLANs 13-15
Creating an Extended-Range VLAN 13-15
Displaying VLANs 13-16
Configuring VLAN Trunks 13-18
Trunking Overview 13-18
802.1Q Configuration Considerations 13-20
Default Layer 2 EthernetInterface VLAN Configuration 13-21
Configuring an Ethernet Interface as a Trunk Port 13-21
Interaction with Other Features 13-21
Configuring a Trunk Port 13-22
Defining the Allowed VLANs on a Trunk 13-23

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Changing the Pruning-Eligible List 13-24
Configuring the Native VLAN for Untagged Traffic 13-25
Load Sharing Using STP 13-26
Load Sharing Using STP Port Priorities 13-26
Load Sharing Using STP Path Cost 13-28
Configuring VMPS 13-30
Understanding VMPS 13-30
Dynamic Port VLAN Membership 13-31
VMPS Database Configuration File 13-31
Default VMPS Configuration 13-33
VMPS Configuration Guidelines 13-33
Configuring the VMPS Client 13-34
Entering the IP Address ofthe VMPS 13-34
Configuring Dynamic Access Ports on VMPS Clients 13-34
Reconfirming VLAN Memberships 13-35
Changing the Reconfirmation Interval 13-35
Changing the Retry Count 13-36
Monitoring the VMPS 13-36
Troubleshooting Dynamic Port VLAN Membership 13-37
VMPS Configuration Example 13-37
CHAPTER 14 Configuring VTP 14-1
Understanding VTP 14-1
The VTP Domain 14-2
VTP Modes 14-3
VTP Advertisements 14-3
VTP Version 2 14-4
VTP Pruning 14-4
Configuring VTP 14-6
Default VTP Configuration 14-6
VTP Configuration Options 14-7
VTP Configuration in Privileged EXEC and Global Configuration Modes 14-7
VTP Configuration in VLAN Configuration Mode 14-7
VTP Configuration Guidelines 14-8
Domain Names 14-8
Passwords 14-8
Upgrading from Previous Software Releases 14-8
VTP Version 14-9
Configuration Requirements 14-9

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Configuring a VTP Server 14-9
Configuring a VTP Client 14-11
Disabling VTP (VTP Transparent Mode) 14-12
Enabling VTP Version 2 14-13
Enabling VTP Pruning 14-14
Adding a VTP Client Switch to a VTP Domain 14-15
Monitoring VTP 14-16
CHAPTER 15 Configuring Voice VLAN 15-1
Understanding Voice VLAN 15-1
Configuring Voice VLAN 15-2
Default Voice VLAN Configuration 15-2
Configuration Guidelines 15-3
Configuring a Port to Connect to aCisco 7960 IP Phone 15-3
Configuring Ports to Carry Voice Traffic in 802.1Q Frames 15-4
Configuring Ports to Carry Voice Traffic in 802.1P Priority Tagged Frames 15-4
Overriding the CoS Priority of Incoming Data Frames 15-5
Configuring the IP Phone to Trust the CoS Priority of Incoming Data Frames 15-5
Displaying Voice VLAN 15-6
CHAPTER 16 Configuring IGMP Snooping and MVR 16-1
Understanding IGMP Snooping 16-1
Joining a Multicast Group 16-2
Leaving a Multicast Group 16-4
Immediate-Leave Processing 16-4
Configuring IGMP Snooping 16-5
Default IGMP Snooping Configuration 16-5
Enabling or Disabling IGMP Snooping 16-5
Setting the Snooping Method 16-6
Configuring a Multicast Router Port 16-7
Configuring a Host Statically to Join a Group 16-8
Enabling IGMP Immediate-Leave Processing 16-9
Displaying IGMP Snooping Information 16-10
Understanding Multicast VLAN Registration 16-11
Using MVR in a Multicast Television Application 16-11
Configuring MVR 16-13
ConfigurationGuidelines and Limitations 16-13
Default MVR Configuration 16-13

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Configuring MVR GlobalParameters 16-14
Configuring MVR Interfaces 16-15
Displaying MVR Information 16-17
Configuring IGMP Filtering 16-18
Default IGMP Filtering Configuration 16-19
Configuring IGMP Profiles 16-19
Applying IGMP Profiles 16-20
Setting the Maximum Number of IGMP Groups 16-21
Displaying IGMP Filtering Configuration 16-22
CHAPTER 17 Configuring Port-Based Traffic Control 17-1
Configuring Storm Control 17-1
Disabling Storm Control 17-2
Configuring Protected Ports 17-3
Configuring Port Security 17-3
Defining the Maximum Secure Address Count 17-4
Enabling Port Security 17-5
Disabling Port Security 17-5
Configuring and Enabling Port Security Aging 17-6
Displaying Port-Based Traffic ControlSettings 17-7
CHAPTER 18 Configuring UDLD 18-1
Understanding UDLD 18-1
Configuring UDLD 18-3
Default UDLD Configuration 18-3
Enabling UDLD Globally 18-3
Enabling UDLD on an Interface 18-4
Resetting an Interface Shut Down by UDLD 18-4
Displaying UDLD Status 18-5
CHAPTER 19 Configuring CDP 19-1
Understanding CDP 19-1
Configuring CDP 19-2
Default CDP Configuration 19-2
Configuring the CDP Characteristics 19-2
Disabling and Enabling CDP 19-3
Disabling and Enabling CDP on an Interface 19-4
Monitoring and Maintaining CDP 19-5

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CHAPTER 20 Configuring SPAN 20-1
Understanding SPAN 20-1
SPAN Concepts and Terminology 20-2
SPAN Session 20-2
Traffic Types 20-2
Source Port 20-3
Destination Port 20-3
SPAN Traffic 20-4
SPAN Interaction with Other Features 20-4
Configuring SPAN 20-5
SPAN Configuration Guidelines 20-5
Creating a SPAN Session and Specifying Ports to Monitor 20-6
Removing Ports from a SPAN Session 20-7
Displaying SPAN Status 20-8
CHAPTER 21 Configuring System Message Logging 21-1
Understanding System Message Logging 21-1
Configuring System Message Logging 21-2
System Log Message Format 21-2
Default System Message Logging Configuration 21-3
Disabling and Enabling Message Logging 21-4
Setting the Message Display Destination Device 21-4
Synchronizing Log Messages 21-6
Enabling and Disabling Timestampson Log Messages 21-7
Enabling and Disabling Sequence Numbers in Log Messages 21-8
Defining the Message Severity Level 21-8
Limiting Syslog Messages Sent to the History Table and to SNMP 21-10
Configuring UNIX Syslog Servers 21-10
Logging Messages to a UNIX Syslog Daemon 21-11
Configuring the UNIX System Logging Facility 21-11
Displaying the Logging Configuration 21-12
CHAPTER 22 Configuring SNMP 22-1
Understanding SNMP 22-1
SNMP Versions 22-2
SNMP Manager Functions 22-2
SNMP Agent Functions 22-3
SNMP Community Strings 22-3
Using SNMP to Access MIB Variables 22-3

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Configuring SNMP 22-4
Default SNMP Configuration 22-4
Disabling the SNMP Agent 22-5
Configuring Community Strings 22-5
Configuring Trap Managers and Enabling Traps 22-7
Setting the Agent Contactand Location Information 22-9
Limiting TFTP Servers Used Through SNMP 22-9
SNMP Examples 22-10
Displaying SNMP Status 22-10
CHAPTER 23 Configuring Network Security with ACLs 23-1
Understanding ACLs 23-1
ACLs 23-2
Handling Fragmented and Unfragmented Traffic 23-3
Understanding Access Control Parameters 23-4
Guidelines for Configuring ACLs on the Catalyst 2950 Switches 23-5
Configuring ACLs 23-6
Unsupported Features 23-6
Creating Standard and Extended IP ACLs 23-7
ACL Numbers 23-7
Creating a Numbered Standard ACL 23-8
Creating a Numbered Extended ACL 23-9
Creating Named Standard and Extended ACLs 23-12
Including Comments About Entries in ACLs 23-14
Applying the ACL to an Interface or Terminal Line 23-15
Displaying ACLs 23-16
Displaying Access Groups 23-17
Examples for Compiling ACLs 23-18
Creating Named MAC Extended ACLs 23-20
Creating MAC Access Groups 23-21
CHAPTER 24 Configuring QoS 24-1
Understanding QoS 24-2
Basic QoS Model 24-3
Classification 24-4
Classification Based on QoS ACLs 24-5
Classification Based on Class Maps and PolicyMaps 24-5
Policing and Marking 24-6
Mapping Tables 24-7

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Queueing and Scheduling 24-8
How Class of Service Works 24-8
PortPriority 24-8
PortScheduling 24-8
CoS and WRR 24-8
Configuring QoS 24-9
Default QoS Configuration 24-9
Configuration Guidelines 24-10
Configuring Classification Using Port TrustStates 24-10
Configuring the Trust State on Ports within the QoS Domain 24-11
Configuring the CoS Value for an Interface 24-13
Configuring a QoS Policy 24-13
Classifying Traffic by Using ACLs 24-14
Classifying Traffic by Using Class Maps 24-17
Classifying,Policing, and Marking Traffic by UsingPolicy Maps 24-18
Configuring CoS Maps 24-21
Configuring the CoS-to-DSCP Map 24-21
Configuring the DSCP-to-CoS Map 24-22
Configuring CoS and WRR 24-23
CLI: Configuring CoS Priority Queues 24-24
Configuring WRR 24-24
Displaying QoS Information 24-25
QoS Configuration Examples 24-25
QoS Configuration for the Common Wiring Closet 24-26
QoS Configuration for the Intelligent Wiring Closet 24-27
CHAPTER 25 Configuring EtherChannels 25-1
Understanding EtherChannels 25-1
Understanding Port-Channel Interfaces 25-2
Understanding the Port Aggregation Protocol 25-3
PAgP Modes 25-3
Physical Learners and Aggregate-Port Learners 25-4
PAgP Interaction with Other Features 25-5
Understanding Load Balancing and Forwarding Methods 25-5
Default EtherChannel Configuration 25-6
EtherChannelConfiguration Guidelines 25-7
Configuring EtherChannels 25-7
Configuring EtherChannel Load Balancing 25-9

Contents
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Catalyst 2950 Desktop Switch Software Configuration Guide 78-11380-04
Configuring the PAgP Learn Method and Priority 25-10
Displaying EtherChannel and PAgP Status 25-10
CHAPTER 26 Troubleshooting 26-1
Avoiding Configuration Conflicts 26-1
Avoiding Autonegotiation Mismatches 26-2
GBIC Security and Identification 26-2
Troubleshooting CMS Sessions 26-3
Copying Configuration Files to Troubleshoot Configuration Problems 26-4
Using Recovery Procedures 26-5
Recovering from Lost Member Connectivity 26-5
Recovering from a Command Switch Failure 26-6
Replacing a Failed Command Switch with a Cluster Member 26-6
Replacing a Failed Command Switch with Another Switch 26-8
Recovering from a Failed Command Switch Without HSRP 26-9
Recovering from a Lost or Forgotten Password 26-9
Recovering from Corrupted Software 26-11
Using Debug Commands 26-11
Enabling Debugging on a Specific Feature 26-12
Enabling All-System Diagnostics 26-12
Redirecting Debug and Error Message Output 26-13
APPENDIX ASupported MIBs A-1
MIB List A-1
Using FTP to Access the MIB Files A-2
I NDEX