Cisco Catalyst 2960-XR User manual

Catalyst 2960-XR Switch Layer 2 Configuration Guide, Cisco IOS
Release 15.0(2)EX1
First Published: August 08, 2013
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Text Part Number: OL-29424-01

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CONTENTS
Preface Preface xi
Document Conventions xi
Related Documentation xiii
Obtaining Documentation and Submitting a Service Request xiii
CHAPTER 1 Using the Command-Line Interface 1
Information About Using the Command-Line Interface 1
Command Modes 1
Using the Help System 3
Understanding Abbreviated Commands 4
No and default Forms of Commands 4
CLI Error Messages 4
Configuration Logging 5
How to Use the CLI to Configure Features 5
Configuring the Command History 5
Changing the Command History Buffer Size 6
Recalling Commands 6
Disabling the Command History Feature 7
Enabling and Disabling Editing Features 7
Editing Commands through Keystrokes 8
Editing Command Lines That Wrap 9
Searching and Filtering Output of show and more Commands 10
Accessing the CLI through a Console Connection or through Telnet 11
CHAPTER 2 Configuring Spanning Tree Protocol 13
Finding Feature Information 13
Restrictions for STP 13
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Information About Spanning Tree Protocol 14
Spanning Tree Protocol 14
Spanning-Tree Topology and BPDUs 15
Bridge ID, Device Priority, and Extended System ID 17
Port Priority Versus Path Cost 18
Spanning-Tree Interface States 18
Blocking State 19
Listening State 20
Learning State 20
Forwarding State 20
Disabled State 20
How a Switch or Port Becomes the Root Switch or Root Port 21
Spanning Tree and Redundant Connectivity 21
Spanning-Tree Address Management 22
Accelerated Aging to Retain Connectivity 22
Spanning-Tree Modes and Protocols 23
Supported Spanning-Tree Instances 23
Spanning-Tree Interoperability and Backward Compatibility 24
STP and IEEE 802.1Q Trunks 24
VLAN-Bridge Spanning Tree 24
Spanning Tree and Switch Stacks 25
Default Spanning-Tree Configuration 25
How to Configure Spanning-Tree Features 26
Changing the Spanning-Tree Mode 26
Disabling Spanning Tree 28
Configuring the Root Switch 29
Configuring a Secondary Root Device 30
Configuring Port Priority 31
Configuring Path Cost 32
Configuring the Device Priority of a VLAN 34
Configuring the Hello Time 35
Configuring the Forwarding-Delay Time for a VLAN 36
Configuring the Maximum-Aging Time for a VLAN 36
Configuring the Transmit Hold-Count 37
Monitoring Spanning-Tree Status 38
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Additional References for Spanning-Tree Protocol 39
Feature Information for STP 40
CHAPTER 3 Configuring Multiple Spanning-Tree Protocol 41
Finding Feature Information 41
Prerequisites for MSTP 41
Restrictions for MSTP 42
Information About MSTP 43
MSTP Configuration 43
MSTP Configuration Guidelines 44
Root Switch 44
Multiple Spanning-Tree Regions 45
IST, CIST, and CST 46
Operations Within an MST Region 46
Operations Between MST Regions 47
IEEE 802.1s Terminology 47
Illustration of MST Regions 48
Hop Count 49
Boundary Ports 49
IEEE 802.1s Implementation 50
Port Role Naming Change 50
Interoperation Between Legacy and Standard Switches 50
Detecting Unidirectional Link Failure 51
MSTP and Switch Stacks 52
Interoperability with IEEE 802.1D STP 52
RSTP Overview 52
Port Roles and the Active Topology 53
Rapid Convergence 54
Synchronization of Port Roles 55
Bridge Protocol Data Unit Format and Processing 56
Processing Superior BPDU Information 57
Processing Inferior BPDU Information 57
Topology Changes 57
Protocol Migration Process 58
Default MSTP Configuration 58
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How to Configure MSTP Features 59
Specifying the MST Region Configuration and Enabling MSTP 59
Configuring the Root Switch 62
Configuring a Secondary Root Switch 63
Configuring Port Priority 64
Configuring Path Cost 65
Configuring the Switch Priority 67
Configuring the Hello Time 68
Configuring the Forwarding-Delay Time 69
Configuring the Maximum-Aging Time 70
Configuring the Maximum-Hop Count 71
Specifying the Link Type to Ensure Rapid Transitions 72
Designating the Neighbor Type 73
Restarting the Protocol Migration Process 75
Monitoring MST Configuration and Status 76
Additional References for MSTP 76
Feature Information for MSTP 77
CHAPTER 4 Configuring Optional Spanning-Tree Features 79
Finding Feature Information 79
Restriction for Optional Spanning-Tree Features 79
Information About Optional Spanning-Tree Features 80
PortFast 80
BPDU Guard 80
BPDU Filtering 81
UplinkFast 82
Cross-Stack UplinkFast 83
How Cross-Stack UplinkFast Works 84
Events That Cause Fast Convergence 86
BackboneFast 86
EtherChannel Guard 89
Root Guard 89
Loop Guard 90
How to Configure Optional Spanning-Tree Features 90
Enabling PortFast 90
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Enabling BPDU Guard 92
Enabling BPDU Filtering 93
Enabling UplinkFast for Use with Redundant Links 95
Disabling UplinkFast 96
Enabling BackboneFast 97
Enabling EtherChannel Guard 98
Enabling Root Guard 99
Enabling Loop Guard 100
Monitoring the Spanning-Tree Status 102
Additional References for Optional Spanning Tree Features 102
Feature Information for Optional Spanning-Tree Features 103
CHAPTER 5 Configuring EtherChannels 105
Finding Feature Information 105
Restrictions for EtherChannels 105
Information About EtherChannels 106
EtherChannel Overview 106
EtherChannel Modes 107
EtherChannel on Switches 108
EtherChannel Link Failover 109
Channel Groups and Port-Channel Interfaces 109
Port Aggregation Protocol 111
PAgP Modes 111
Silent Mode 112
PAgP Learn Method and Priority 112
PAgP Interaction with Virtual Switches and Dual-Active Detection 113
PAgP Interaction with Other Features 114
Link Aggregation Control Protocol 114
LACP Modes 114
LACP Interaction with Other Features 115
EtherChannel On Mode 115
Load-Balancing and Forwarding Methods 115
MAC Address Forwarding 116
IP Address Forwarding 116
Load-Balancing Advantages 117
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EtherChannel and Switch Stacks 118
Switch Stacks and PAgP 119
Switch Stacks and LACP 119
Default EtherChannel Configuration 119
EtherChannel Configuration Guidelines 120
Layer 2 EtherChannel Configuration Guidelines 122
Layer 3 EtherChannel Configuration Guidelines 123
How to Configure EtherChannels 123
Configuring Layer 2 EtherChannels 123
Configuring Layer 3 EtherChannels 126
Creating Port-Channel Logical Interfaces 126
Configuring the Physical Interfaces 127
Configuring EtherChannel Load-Balancing 129
Configuring the PAgP Learn Method and Priority 130
Configuring LACP Hot-Standby Ports 132
Configuring the LACP System Priority 132
Configuring the LACP Port Priority 133
Monitoring EtherChannel, PAgP, and LACP Status 135
Configuration Examples for Configuring EtherChannels 136
Configuring Layer 2 EtherChannels: Examples 136
Configuring Port-Channel Logical Interfaces: Example 136
Configuring EtherChannel Physical Interfaces: Examples 137
Additional References for EtherChannels 137
Feature Information for EtherChannels 138
CHAPTER 6 Configuring Link-State Tracking 139
Finding Feature Information 139
Restrictions for Configuring Link-State Tracking 139
Understanding Link-State Tracking 140
How to Configure Link-State Tracking 143
Monitoring Link-State Tracking 144
Configuring Link-State Tracking: Example 144
Additional References for Link-State Tracking 145
Feature Information for Link-State Tracking 146
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CHAPTER 7 Configuring Flex Links and the MAC Address-Table Move Update Feature 147
Finding Feature Information 147
Restrictions for Configuring Flex Links and MAC Address-Table Move Update 147
Information About Flex Links and MAC Address-Table Move Update 148
Flex Links 148
Flex Links Configuration 149
VLAN Flex Links Load Balancing and Support 149
Multicast Fast Convergence with Flex Links Failover 150
Learning the Other Flex Links Port as the mrouter Port 150
Generating IGMP Reports 150
Leaking IGMP Reports 151
MAC Address-Table Move Update 151
Flex Links VLAN Load Balancing Configuration Guidelines 153
MAC Address-Table Move Update Configuration Guidelines 153
Default Flex Links and MAC Address-Table Move Update Configuration 153
How to Configure Flex Links and the MAC Address-Table Move Update Feature 154
Configuring Flex Links 154
Configuring a Preemption Scheme for a Pair of Flex Links 155
Configuring VLAN Load Balancing on Flex Links 157
Configuring MAC Address-Table Move Update 158
Configuring a Switch to Obtain and Process MAC Address-Table Move Update
Messages 159
Monitoring Flex Links and the MAC Address-Table Move Update 160
Configuration Examples for Flex Links 161
Configuring Flex Links: Examples 161
Configuring VLAN Load Balancing on Flex Links: Examples 161
Configuring the MAC Address-Table Move Update: Examples 163
Configuring Multicast Fast Convergence with Flex Links Failover: Examples 163
Additional References for Flex Links and MAC Address-Table Move Update 165
Feature Information for Flex Links and MAC Address-Table Move Update 166
CHAPTER 8 Configuring UniDirectional Link Detection 167
Finding Feature Information 167
Restrictions for Configuring UDLD 167
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Information About UDLD 168
Modes of Operation 168
Normal Mode 168
Aggressive Mode 168
Methods to Detect Unidirectional Links 169
Neighbor Database Maintenance 169
Event-Driven Detection and Echoing 169
UDLD Reset Options 170
Default UDLD Configuration 170
How to Configure UDLD 171
Enabling UDLD Globally 171
Enabling UDLD on an Interface 172
Monitoring and Maintaining UDLD 173
Additional References for UDLD 174
Feature Information for UDLD 175
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