Cisco 2975 - Catalyst LAN Base Switch User manual

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Catalyst 2975 Switch Software
Configuration Guide
Cisco IOS Release 12.2(55)SE
August 2010
Text Part Number: OL-19720-02

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Catalyst 2975 Switch Software Configuration Guide
© 2009–2010 Cisco Systems, Inc. All rights reserved.

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CONTENTS
Preface xxxv
Audience xxxv
Purpose xxxv
Conventions xxxvi
Related Publications xxxvi
Obtaining Documentation, Obtaining Support, and Security Guidelines xxxvii
CHAPTER 1Overview 1-1
Features 1-1
Ease-of-Deployment and Ease-of-Use Features 1-2
Performance Features 1-3
Management Options 1-5
Manageability Features 1-5
Availability and Redundancy Features 1-7
VLAN Features 1-8
Security Features 1-8
QoS and CoS Features 1-11
Layer 3 Features 1-12
Power over Ethernet Features 1-12
Monitoring Features 1-12
Default Settings After Initial Switch Configuration 1-13
Network Configuration Examples 1-15
Design Concepts for Using the Switch 1-15
Small to Medium-Sized Network Using Catalyst 2975 Switches 1-19
Long-Distance, High-Bandwidth Transport Configuration 1-20
Where to Go Next 1-21
CHAPTER 2Using the Command-Line Interface 2-1
Understanding Command Modes 2-1
Understanding the Help System 2-3
Understanding Abbreviated Commands 2-4
Understanding no and default Forms of Commands 2-4
Understanding CLI Error Messages 2-5

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Using Configuration Logging 2-5
Using Command History 2-6
Changing the Command History Buffer Size 2-6
Recalling Commands 2-6
Disabling the Command History Feature 2-7
Using Editing Features 2-7
Enabling and Disabling Editing Features 2-7
Editing Commands through Keystrokes 2-8
Editing Command Lines that Wrap 2-9
Searching and Filtering Output of show and more Commands 2-10
Accessing the CLI 2-10
Accessing the CLI through a Console Connection or through Telnet 2-10
CHAPTER 3Assigning the Switch IP Address and Default Gateway 3-1
Understanding the Boot Process 3-2
Assigning Switch Information 3-3
Default Switch Information 3-3
Understanding DHCP-Based Autoconfiguration 3-4
DHCP Client Request Process 3-4
Understanding DHCP-based Autoconfiguration and Image Update 3-5
DHCP Autoconfiguration 3-5
DHCP Auto-Image Update 3-6
Limitations and Restrictions 3-6
Configuring DHCP-Based Autoconfiguration 3-7
DHCP Server Configuration Guidelines 3-7
Configuring the TFTP Server 3-8
Configuring the DNS 3-8
Configuring the Relay Device 3-9
Obtaining Configuration Files 3-9
Example Configuration 3-10
Configuring the DHCP Auto Configuration and Image Update Features 3-12
Configuring DHCP Autoconfiguration (Only Configuration File) 3-12
Configuring DHCP Auto-Image Update (Configuration File and Image) 3-13
Configuring the Client 3-14
Manually Assigning IP Information 3-15
Checking and Saving the Running Configuration 3-16
Configuring the NVRAM Buffer Size 3-17

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Modifying the Startup Configuration 3-18
Default Boot Configuration 3-18
Automatically Downloading a Configuration File 3-18
Specifying the Filename to Read and Write the System Configuration 3-19
Booting Manually 3-19
Booting a Specific Software Image 3-20
Controlling Environment Variables 3-21
Scheduling a Reload of the Software Image 3-23
Configuring a Scheduled Reload 3-23
Displaying Scheduled Reload Information 3-24
CHAPTER 4Configuring Cisco IOS Configuration Engine 4-1
Understanding Cisco Configuration Engine Software 4-1
Configuration Service 4-2
Event Service 4-3
NameSpace Mapper 4-3
What You Should Know About the CNS IDs and Device Hostnames 4-3
ConfigID 4-3
DeviceID 4-4
Hostname and DeviceID 4-4
Using Hostname, DeviceID, and ConfigID 4-4
Understanding Cisco IOS Agents 4-5
Initial Configuration 4-5
Incremental (Partial) Configuration 4-6
Synchronized Configuration 4-6
Configuring Cisco IOS Agents 4-6
Enabling Automated CNS Configuration 4-6
Enabling the CNS Event Agent 4-7
Enabling the Cisco IOS CNS Agent 4-9
Enabling an Initial Configuration 4-9
Enabling a Partial Configuration 4-12
Displaying CNS Configuration 4-13
CHAPTER 5Clustering Switches 5-1
Understanding Switch Clusters 5-1
Cluster Command Switch Characteristics 5-3
Standby Cluster Command Switch Characteristics 5-3
Candidate Switch and Cluster Member Switch Characteristics 5-4

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Planning a Switch Cluster 5-5
Automatic Discovery of Cluster Candidates and Members 5-5
Discovery Through CDP Hops 5-5
Discovery Through Non-CDP-Capable and Noncluster-Capable Devices 5-7
Discovery Through Different VLANs 5-7
Discovery Through Different Management VLANs 5-8
Discovery of Newly Installed Switches 5-9
HSRP and Standby Cluster Command Switches 5-10
Virtual IP Addresses 5-11
Other Considerations for Cluster Standby Groups 5-11
Automatic Recovery of Cluster Configuration 5-12
IP Addresses 5-13
Hostnames 5-13
Passwords 5-14
SNMP Community Strings 5-14
Switch Clusters and Switch Stacks 5-14
TACACS+ and RADIUS 5-16
LRE Profiles 5-16
Using the CLI to Manage Switch Clusters 5-16
Using SNMP to Manage Switch Clusters 5-17
CHAPTER 6Managing Switch Stacks 6-1
Understanding Stacks 6-1
Stack Membership 6-3
Master Election 6-4
Stack MAC Address 6-5
Member Numbers 6-6
Member Priority Values 6-6
Stack Offline Configuration 6-7
Effects of Adding a Provisioned Switch to a Stack 6-7
Effects of Replacing a Provisioned Switch in a Stack 6-9
Effects of Removing a Provisioned Switch from a Stack 6-9
Stack Software Compatibility Recommendations 6-9
Stack Protocol Version Compatibility 6-9
Major Version Number Incompatibility Among Switches 6-9
Minor Version Number Incompatibility Among Switches 6-9
Understanding Auto-Upgrade and Auto-Advise 6-10
Auto-Upgrade and Auto-Advise Example Messages 6-11
Incompatible Software and Member Image Upgrades 6-13

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Stack Configuration Files 6-13
Additional Considerations for System-Wide Configuration on Switch Stacks 6-13
Stack Management Connectivity 6-14
Stack Through an IP Address 6-14
Stack Through an SSH Session 6-14
Stack Through Console Ports 6-15
Specific Members 6-15
Stack Configuration Scenarios 6-15
Configuring the Switch Stack 6-17
Default Switch Stack Configuration 6-17
Enabling Persistent MAC Address 6-17
Assigning Stack Member Information 6-19
Assigning a Member Number 6-19
Setting the Member Priority Value 6-20
Provisioning a New Member for a Stack 6-20
Changing the Stack Membership 6-21
Accessing the CLI of a Specific Member 6-22
Displaying Stack Information 6-22
Troubleshooting Stacks 6-23
Manually Disabling a Stack Port 6-23
Re-Enabling a Stack Port While Another Member Starts 6-23
Understanding the show switch stack-ports summary Output 6-24
Identifying Loopback Problems 6-25
Software Loopback 6-25
Software Loopback Example: No Connected Stack Cable 6-26
Software Loopback Examples: Connected Stack Cables 6-26
Hardware Loopback 6-27
Hardware Loopback Example: LINK OK event 6-27
Hardware Loop Example: LINK NOT OK Event 6-28
Finding a Disconnected StackWiseStackCable 6-28
Fixing a Bad Connection Between Stack Ports 6-29
CHAPTER 7Administering the Switch 7-1
Managing the System Time and Date 7-1
Understanding the System Clock 7-1
Understanding Network Time Protocol 7-2

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Configuring NTP 7-4
Default NTP Configuration 7-4
Configuring NTP Authentication 7-5
Configuring NTP Associations 7-6
Configuring NTP Broadcast Service 7-7
Configuring NTP Access Restrictions 7-8
Configuring the Source IP Address for NTP Packets 7-10
Displaying the NTP Configuration 7-11
Configuring Time and Date Manually 7-11
Setting the System Clock 7-11
Displaying the Time and Date Configuration 7-12
Configuring the Time Zone 7-12
Configuring Summer Time (Daylight Saving Time) 7-13
Configuring a System Name and Prompt 7-14
Default System Name and Prompt Configuration 7-15
Configuring a System Name 7-15
Understanding DNS 7-15
Default DNS Configuration 7-16
Setting Up DNS 7-16
Displaying the DNS Configuration 7-17
Creating a Banner 7-17
Default Banner Configuration 7-17
Configuring a Message-of-the-Day Login Banner 7-18
Configuring a Login Banner 7-19
Managing the MAC Address Table 7-19
Building the Address Table 7-20
MAC Addresses and VLANs 7-20
MAC Addresses and Switch Stacks 7-21
Default MAC Address Table Configuration 7-21
Changing the Address Aging Time 7-21
Removing Dynamic Address Entries 7-22
Configuring MAC Address Change Notification Traps 7-22
Configuring MAC Address Move Notification Traps 7-24
Configuring MAC Threshold Notification Traps 7-25
Adding and Removing Static Address Entries 7-26
Configuring Unicast MAC Address Filtering 7-27
Disabling MAC Address Learning on a VLAN 7-28
Displaying Address Table Entries 7-30
Managing the ARP Table 7-30

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CHAPTER 8Configuring SDM Templates 8-1
Understanding the SDM Templates 8-1
SDM Templates and Switch Stacks 8-2
Configuring the Switch SDM Template 8-3
Default SDM Template 8-3
SDM Template Configuration Guidelines 8-3
Setting the SDM Template 8-4
.Displaying the SDM Templates 8-4
CHAPTER 9Configuring Switch-Based Authentication 9-1
Preventing Unauthorized Access to Your Switch 9-1
Protecting Access to Privileged EXEC Commands 9-2
Default Password and Privilege Level Configuration 9-3
Setting or Changing a Static Enable Password 9-3
Protecting Enable and Enable Secret Passwords with Encryption 9-4
Disabling Password Recovery 9-5
Setting a Telnet Password for a Terminal Line 9-6
Configuring Username and Password Pairs 9-7
Configuring Multiple Privilege Levels 9-8
Setting the Privilege Level for a Command 9-8
Changing the Default Privilege Level for Lines 9-9
Logging into and Exiting a Privilege Level 9-10
Controlling Switch Access with TACACS+ 9-10
Understanding TACACS+ 9-10
TACACS+ Operation 9-12
Configuring TACACS+ 9-13
Default TACACS+ Configuration 9-13
Identifying the TACACS+ Server Host and Setting the Authentication Key 9-13
Configuring TACACS+ Login Authentication 9-14
Configuring TACACS+ Authorization for Privileged EXEC Access and Network Services 9-16
Starting TACACS+ Accounting 9-17
Establishing a Session with a Router if the AAA Server is Unreachable 9-18
Displaying the TACACS+ Configuration 9-18
Controlling Switch Access with RADIUS 9-18
Understanding RADIUS 9-18
RADIUS Operation 9-20
RADIUS Change of Authorization 9-20
Overview 9-20
Change-of-Authorization Requests 9-21

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CoA Request Response Code 9-22
CoA Request Commands 9-23
Stacking Guidelines for Session Termination 9-26
Configuring RADIUS 9-27
Default RADIUS Configuration 9-27
Identifying the RADIUS Server Host 9-28
Configuring RADIUS Login Authentication 9-30
Defining AAA Server Groups 9-32
Configuring RADIUS Authorization for User Privileged Access and Network Services 9-34
Starting RADIUS Accounting 9-35
Establishing a Session with a Router if the AAA Server is Unreachable 9-36
Configuring Settings for All RADIUS Servers 9-36
Configuring the Switch to Use Vendor-Specific RADIUS Attributes 9-36
Configuring the Switch for Vendor-Proprietary RADIUS Server Communication 9-38
Configuring CoA on the Switch 9-39
Monitoring and Troubleshooting CoA Functionality 9-40
Configuring RADIUS Server Load Balancing 9-40
Displaying the RADIUS Configuration 9-40
Configuring the Switch for Local Authentication and Authorization 9-40
Configuring the Switch for Secure Shell 9-41
Understanding SSH 9-42
SSH Servers, Integrated Clients, and Supported Versions 9-42
Limitations 9-43
Configuring SSH 9-43
Configuration Guidelines 9-43
Setting Up the Switch to Run SSH 9-43
Configuring the SSH Server 9-44
Displaying the SSH Configuration and Status 9-45
Configuring the Switch for Secure Socket Layer HTTP 9-46
Understanding Secure HTTP Servers and Clients 9-46
Certificate Authority Trustpoints 9-46
CipherSuites 9-48
Configuring Secure HTTP Servers and Clients 9-48
Default SSL Configuration 9-48
SSL Configuration Guidelines 9-49
Configuring a CA Trustpoint 9-49
Configuring the Secure HTTP Server 9-50
Configuring the Secure HTTP Client 9-51
Displaying Secure HTTP Server and Client Status 9-52

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Configuring the Switch for Secure Copy Protocol 9-52
Information About Secure Copy 9-53
CHAPTER 10 Configuring IEEE 802.1x Port-Based Authentication 10-1
Understanding IEEE 802.1x Port-Based Authentication 10-1
Device Roles 10-2
Authentication Process 10-3
Authentication Initiation and Message Exchange 10-5
Authentication Manager 10-7
Port-Based Authentication Methods 10-7
Per-User ACLs and Filter-Ids 10-8
Authentication Manager CLI Commands 10-9
Ports in Authorized and Unauthorized States 10-10
802.1x Authentication and Switch Stacks 10-11
802.1x Host Mode 10-12
Multidomain Authentication 10-12
802.1x Multiple Authentication Mode 10-13
MAC Move 10-14
MAC Replace 10-15
802.1x Accounting 10-15
802.1x Accounting Attribute-Value Pairs 10-16
802.1x Readiness Check 10-17
802.1x Authentication with VLAN Assignment 10-17
802.1x Authentication with Downloadable ACLs and Redirect URLs 10-18
Cisco Secure ACS and Attribute-Value Pairs for the Redirect URL 10-20
Cisco Secure ACS and Attribute-Value Pairs for Downloadable ACLs 10-20
VLAN ID-based MAC Authentication 10-20
802.1x Authentication with Guest VLAN 10-21
802.1x Authentication with Restricted VLAN 10-22
802.1x Authentication with Inaccessible Authentication Bypass 10-23
Support on Multiple-Authentication Ports 10-23
Authentication Results 10-23
Feature Interactions 10-24
802.1x Authentication with Voice VLAN Ports 10-24
802.1x Authentication with Port Security 10-25
802.1x Authentication with Wake-on-LAN 10-26
802.1x Authentication with MAC Authentication Bypass 10-26
802.1x User Distribution 10-28
802.1x User Distribution Configuration Guidelines 10-28
Network Admission Control Layer 2 802.1x Validation 10-29

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Flexible Authentication Ordering 10-29
Open1x Authentication 10-29
Using Voice Aware 802.1x Security 10-30
802.1x Supplicant and Authenticator Switches with Network Edge Access Topology (NEAT) 10-30
Guidelines 10-31
Using IEEE 802.1x Authentication with ACLs and the RADIUS Filter-Id Attribute 10-31
Common Session ID 10-32
Configuring 802.1x Authentication 10-32
Default 802.1x Authentication Configuration 10-33
802.1x Authentication Configuration Guidelines 10-35
802.1x Authentication 10-35
VLAN Assignment, Guest VLAN, Restricted VLAN, and Inaccessible Authentication
Bypass 10-36
MAC Authentication Bypass 10-36
Maximum Number of Allowed Devices Per Port 10-37
Configuring 802.1x Readiness Check 10-37
Configuring Voice Aware 802.1x Security 10-38
Configuring 802.1x Violation Modes 10-39
Configuring 802.1x Authentication 10-40
Configuring the Switch-to-RADIUS-Server Communication 10-41
Configuring the Host Mode 10-43
Configuring Periodic Re-Authentication 10-44
Manually Re-Authenticating a Client Connected to a Port 10-45
Changing the Quiet Period 10-45
Changing the Switch-to-Client Retransmission Time 10-46
Setting the Switch-to-Client Frame-Retransmission Number 10-47
Setting the Re-Authentication Number 10-47
Enabling MAC Move 10-48
Enabling MAC Replace 10-48
Configuring 802.1x Accounting 10-49
Configuring a Guest VLAN 10-50
Configuring a Restricted VLAN 10-51
Configuring the Inaccessible Authentication Bypass Feature 10-53
Configuring 802.1x Authentication with WoL 10-56
Configuring MAC Authentication Bypass 10-57
Configuring 802.1x User Distribution 10-58
Configuring NAC Layer 2 802.1x Validation 10-59
Configuring an Authenticator and a Supplicant Switch with NEAT 10-60
Configuring NEAT with Auto Smartports Macros 10-61

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Configuring 802.1x Authentication with Downloadable ACLs and Redirect URLs 10-61
Configuring Downloadable ACLs 10-62
Configuring a Downloadable Policy 10-62
Configuring VLAN ID-based MAC Authentication 10-64
Configuring Flexible Authentication Ordering 10-64
Configuring Open1x 10-65
Disabling 802.1x Authentication on the Port 10-65
Resetting the 802.1x Authentication Configuration to the Default Values 10-66
Displaying 802.1x Statistics and Status 10-67
CHAPTER 11 Configuring Web-Based Authentication 11-1
Understanding Web-Based Authentication 11-1
Device Roles 11-2
Host Detection 11-2
Session Creation 11-3
Authentication Process 11-3
Local Web Authentication Banner 11-4
Web Authentication Customizable Web Pages 11-6
Guidelines 11-6
Web-based Authentication Interactions with Other Features 11-7
Port Security 11-7
LAN Port IP 11-8
Gateway IP 11-8
ACLs 11-8
Context-Based Access Control 11-8
802.1x Authentication 11-8
EtherChannel 11-8
Configuring Web-Based Authentication 11-9
Default Web-Based Authentication Configuration 11-9
Web-Based Authentication Configuration Guidelines and Restrictions 11-9
Web-Based Authentication Configuration Task List 11-10
Configuring the Authentication Rule and Interfaces 11-10
Configuring AAA Authentication 11-11
Configuring Switch-to-RADIUS-Server Communication 11-11
Configuring the HTTP Server 11-13
Customizing the Authentication Proxy Web Pages 11-13
Specifying a Redirection URL for Successful Login 11-15
Configuring an AAA Fail Policy 11-15
Configuring the Web-Based Authentication Parameters 11-16

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Configuring a Web Authentication Local Banner 11-16
Removing Web-Based Authentication Cache Entries 11-17
Displaying Web-Based Authentication Status 11-17
CHAPTER 12 Configuring Interface Characteristics 12-1
Understanding Interface Types 12-1
Port-Based VLANs 12-2
Switch Ports 12-2
Access Ports 12-2
Trunk Ports 12-3
Switch Virtual Interfaces 12-3
EtherChannel Port Groups 12-4
Dual-Purpose Uplink Ports 12-4
Power over Ethernet Ports 12-4
Supported Protocols and Standards 12-5
Powered-Device Detection and Initial Power Allocation 12-5
Power Management Modes 12-7
Power Monitoring and Power Policing 12-8
Connecting Interfaces 12-10
Using Interface Configuration Mode 12-11
Procedures for Configuring Interfaces 12-12
Configuring a Range of Interfaces 12-12
Configuring and Using Interface Range Macros 12-14
Configuring Ethernet Interfaces 12-16
Default Ethernet Interface Configuration 12-16
Setting the Type of a Dual-Purpose Uplink Port 12-17
Configuring Interface Speed and Duplex Mode 12-19
Speed and Duplex Configuration Guidelines 12-19
Setting the Interface Speed and Duplex Parameters 12-20
Configuring IEEE 802.3x Flow Control 12-21
Configuring Auto-MDIX on an Interface 12-22
Configuring a Power Management Mode on a PoE Port 12-23
Budgeting Power for Devices Connected to a PoE Port 12-24
Configuring Power Policing 12-26
Adding a Description for an Interface 12-27
Configuring Layer 3 SVIs 12-27
Configuring the System MTU 12-28
Monitoring and Maintaining the Interfaces 12-29
Monitoring Interface Status 12-30

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Clearing and Resetting Interfaces and Counters 12-30
Shutting Down and Restarting the Interface 12-31
CHAPTER 13 Configuring VLANs 13-1
Understanding VLANs 13-1
Supported VLANs 13-2
VLAN Port Membership Modes 13-3
Configuring Normal-Range VLANs 13-4
Token Ring VLANs 13-5
Normal-Range VLAN Configuration Guidelines 13-5
Configuring Normal-Range VLANs 13-6
Default Ethernet VLAN Configuration 13-6
Creating or Modifying an Ethernet VLAN 13-7
Deleting a VLAN 13-8
Assigning Static-Access Ports to a VLAN 13-9
Configuring Extended-Range VLANs 13-10
Default VLAN Configuration 13-10
Extended-Range VLAN Configuration Guidelines 13-10
Creating an Extended-Range VLAN 13-11
Displaying VLANs 13-12
Configuring VLAN Trunks 13-13
Trunking Overview 13-13
IEEE 802.1Q Configuration Considerations 13-14
Default Layer 2 Ethernet Interface VLAN Configuration 13-14
Configuring an Ethernet Interface as a Trunk Port 13-15
Interaction with Other Features 13-15
Configuring a Trunk Port 13-16
Defining the Allowed VLANs on a Trunk 13-17
Changing the Pruning-Eligible List 13-18
Configuring the Native VLAN for Untagged Traffic 13-19
Configuring Trunk Ports for Load Sharing 13-19
Load Sharing Using STP Port Priorities 13-20
Load Sharing Using STP Path Cost 13-21
Configuring VMPS 13-23
Understanding VMPS 13-23
Dynamic-Access Port VLAN Membership 13-24
Default VMPS Client Configuration 13-24
VMPS Configuration Guidelines 13-24
Configuring the VMPS Client 13-25

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Entering the IP Address of the VMPS 13-25
Configuring Dynamic-Access Ports on VMPS Clients 13-26
Reconfirming VLAN Memberships 13-26
Changing the Reconfirmation Interval 13-27
Changing the Retry Count 13-27
Monitoring the VMPS 13-28
Troubleshooting Dynamic-Access Port VLAN Membership 13-28
VMPS Configuration Example 13-28
CHAPTER 14 Configuring Voice VLAN 14-1
Understanding Voice VLAN 14-1
Cisco IP Phone Voice Traffic 14-2
Cisco IP Phone Data Traffic 14-3
Configuring Voice VLAN 14-3
Default Voice VLAN Configuration 14-3
Voice VLAN Configuration Guidelines 14-3
Configuring a Port Connected to a Cisco 7960 IP Phone 14-5
Configuring Cisco IP Phone Voice Traffic 14-5
Configuring the Priority of Incoming Data Frames 14-6
Displaying Voice VLAN 14-7
CHAPTER 15 Configuring VTP 15-1
Understanding VTP 15-1
The VTP Domain 15-2
VTP Modes 15-3
VTP Advertisements 15-4
VTP Version 2 15-4
VTP Version 3 15-5
VTP Pruning 15-6
VTP and Switch Stacks 15-7
Configuring VTP 15-8
Default VTP Configuration 15-8
VTP Configuration Guidelines 15-8
Domain Names 15-9
Passwords 15-9
VTP Version 15-10
Configuration Requirements 15-10

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Configuring VTP Mode 15-11
Configuring a VTP Version 3 Password 15-13
Configuring a VTP Version 3 Primary Server 15-13
Enabling the VTP Version 15-14
Enabling VTP Pruning 15-15
Configuring VTP on a Per-Port Basis 15-15
Adding a VTP Client Switch to a VTP Domain 15-16
Monitoring VTP 15-17
CHAPTER 16 Configuring STP 16-1
Understanding Spanning-Tree Features 16-1
STP Overview 16-2
Spanning-Tree Topology and BPDUs 16-3
Bridge ID, Switch Priority, and Extended System ID 16-5
Spanning-Tree Interface States 16-5
Blocking State 16-7
Listening State 16-7
Learning State 16-7
Forwarding State 16-7
Disabled State 16-8
How a Switch or Port Becomes the Root Switch or Root Port 16-8
Spanning Tree and Redundant Connectivity 16-9
Spanning-Tree Address Management 16-9
Accelerated Aging to Retain Connectivity 16-9
Spanning-Tree Modes and Protocols 16-10
Supported Spanning-Tree Instances 16-10
Spanning-Tree Interoperability and Backward Compatibility 16-11
STP and IEEE 802.1Q Trunks 16-11
Spanning Tree and Switch Stacks 16-12
Configuring Spanning-Tree Features 16-12
Default Spanning-Tree Configuration 16-13
Spanning-Tree Configuration Guidelines 16-13
Changing the Spanning-Tree Mode. 16-15
Disabling Spanning Tree 16-16
Configuring the Root Switch 16-16
Configuring a Secondary Root Switch 16-18
Configuring Port Priority 16-18
Configuring Path Cost 16-20
Configuring the Switch Priority of a VLAN 16-21

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Configuring Spanning-Tree Timers 16-22
Configuring the Hello Time 16-22
Configuring the Forwarding-Delay Time for a VLAN 16-23
Configuring the Maximum-Aging Time for a VLAN 16-23
Configuring the Transmit Hold-Count 16-24
Displaying the Spanning-Tree Status 16-24
CHAPTER 17 Configuring MSTP 17-1
Understanding MSTP 17-2
Multiple Spanning-Tree Regions 17-2
IST, CIST, and CST 17-3
Operations Within an MST Region 17-3
Operations Between MST Regions 17-4
IEEE 802.1s Terminology 17-5
Hop Count 17-6
Boundary Ports 17-6
IEEE 802.1s Implementation 17-7
Port Role Naming Change 17-7
Interoperation Between Legacy and Standard Switches 17-7
Detecting Unidirectional Link Failure 17-8
MSTP and Switch Stacks 17-9
Interoperability with IEEE 802.1D STP 17-9
Understanding RSTP 17-9
Port Roles and the Active Topology 17-10
Rapid Convergence 17-11
Synchronization of Port Roles 17-12
Bridge Protocol Data Unit Format and Processing 17-13
Processing Superior BPDU Information 17-14
Processing Inferior BPDU Information 17-14
Topology Changes 17-14
Configuring MSTP Features 17-15
Default MSTP Configuration 17-16
MSTP Configuration Guidelines 17-16
Specifying the MST Region Configuration and Enabling MSTP 17-17
Configuring the Root Switch 17-19
Configuring a Secondary Root Switch 17-20
Configuring Port Priority 17-21
Configuring Path Cost 17-23
Configuring the Switch Priority 17-24

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Configuring the Hello Time 17-25
Configuring the Forwarding-Delay Time 17-25
Configuring the Maximum-Aging Time 17-26
Configuring the Maximum-Hop Count 17-26
Specifying the Link Type to Ensure Rapid Transitions 17-27
Designating the Neighbor Type 17-27
Restarting the Protocol Migration Process 17-28
Displaying the MST Configuration and Status 17-28
CHAPTER 18 Configuring Optional Spanning-Tree Features 18-1
Understanding Optional Spanning-Tree Features 18-1
Understanding Port Fast 18-2
Understanding BPDU Guard 18-2
Understanding BPDU Filtering 18-3
Understanding UplinkFast 18-3
Understanding Cross-Stack UplinkFast 18-5
How CSUF Works 18-6
Events that Cause Fast Convergence 18-7
Understanding BackboneFast 18-7
Understanding EtherChannel Guard 18-10
Understanding Root Guard 18-10
Understanding Loop Guard 18-11
Configuring Optional Spanning-Tree Features 18-12
Default Optional Spanning-Tree Configuration 18-12
Optional Spanning-Tree Configuration Guidelines 18-12
Enabling Port Fast 18-13
Enabling BPDU Guard 18-14
Enabling BPDU Filtering 18-15
Enabling UplinkFast for Use with Redundant Links 18-16
Enabling Cross-Stack UplinkFast 18-17
Enabling BackboneFast 18-17
Enabling EtherChannel Guard 18-17
Enabling Root Guard 18-18
Enabling Loop Guard 18-19
Displaying the Spanning-Tree Status 18-19
CHAPTER 19 Configuring Flex Links and the MAC Address-Table Move Update Feature 19-1
Understanding Flex Links and the MAC Address-Table Move Update 19-1
Flex Links 19-1

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VLAN Flex Link Load Balancing and Support 19-3
Flex Link Multicast Fast Convergence 19-3
Learning the Other Flex Link Port as the mrouter Port 19-3
Generating IGMP Reports 19-4
Leaking IGMP Reports 19-4
Configuration Examples 19-4
MAC Address-Table Move Update 19-6
Configuring Flex Links and the MAC Address-Table Move Update 19-7
Default Configuration 19-8
Configuration Guidelines 19-8
Configuring Flex Links 19-9
Configuring VLAN Load Balancing on Flex Links 19-11
Configuring the MAC Address-Table Move Update Feature 19-12
Monitoring Flex Links and the MAC Address-Table Move Update 19-14
CHAPTER 20 Configuring DHCP Features and IP Source Guard Features 20-1
Understanding DHCP Snooping 20-1
DHCP Server 20-2
DHCP Relay Agent 20-2
DHCP Snooping 20-2
Option-82 Data Insertion 20-4
DHCP Snooping Binding Database 20-7
DHCP Snooping and Switch Stacks 20-8
Configuring DHCP Snooping 20-9
Default DHCP Snooping Configuration 20-9
DHCP Snooping Configuration Guidelines 20-9
Configuring the DHCP Relay Agent 20-11
Enabling DHCP Snooping and Option 82 20-11
Enabling the DHCP Snooping Binding Database Agent 20-13
Displaying DHCP Snooping Information 20-14
Understanding IP Source Guard 20-15
Source IP Address Filtering 20-15
Source IP and MAC Address Filtering 20-15
IP Source Guard for Static Hosts 20-16
Configuring IP Source Guard 20-17
Default IP Source Guard Configuration 20-17
IP Source Guard Configuration Guidelines 20-17
Enabling IP Source Guard 20-18