First Published February 29 Last Modified March 22
Americas Headquarters
Page
N T E N T S
Configuring VLANs
Configuring Private VLANs
Configuring Rapid PVST+
Configuring Multiple Spanning Tree
Configuring the Port Priority
Configuring Lldp
Configuring Igmp Snooping
Convention Description
Preface
Audience
Document Conventions
Italic screen font
Release Notes
Installation and Upgrade Guides
Configuration Guides
Error and System Messages
Obtaining Documentation and Submitting a Service Request
Changed Release
Feature Description Added or
Switching mode. There are two switching
New and Changed Information for this Release
OL-26590-01
This chapter contains the following sections
Layer 2 Ethernet Switching Overview
Overview
VLANs
STP Overview
Private VLANs
Spanning Tree
STP Extensions
Rapid PVST+
Overview STP Extensions
Information About Ethernet Interfaces
Configuring Ethernet Interfaces
About the Interface Command
About the Unidirectional Link Detection Parameter
Udld Aggressive and Nonaggressive Modes
Default Udld Configuration
Following table shows the default Udld configuration
Feature
About Interface Speed
About the Error-Disabled State
Default CDP Configuration
Following table shows the default CDP configuration
About Port Profiles
Configuring Ethernet Interfaces
About the Debounce Timer Parameters
About MTU Configuration
Aggressive
Configuring the Udld Mode
Command or Action Purpose Step
Switch# configure terminal
Running-config startup-config
Changing an Interface Port Mode
Command or Action
Running-config bootflash
Transceiver inserted into it
Configuring Interface Speed
Slot /port
Disabling Link Negotiation
Command or Action Purpose
Serial-number system-name
Configuring the CDP Characteristics
Advertise v1
Device-id mac-address
Seconds
Enabling or Disabling CDP
Example
Enabling the Error-Disabled Detection
Copy running-config startup-config
Enabling the Error-Disabled Recovery
Configuring the Error-Disabled Recovery Interval
Config t Enters configuration mode
Show interface status err-disabled
Configuring the Debounce Timer
Configuring the Description Parameter
Errdisable recovery interval interval
Disabling and Restarting Ethernet Interfaces
Switchconfig-if# shutdown Disables the interface
Displaying Interface Information
Command Purpose
Displaying Input Packet Discard Information
Following example shows how to display the CDP neighbors
Parameter Default Setting
Default Physical Ethernet Settings
Page
OL-26590-01
Understanding VLANs
Configuring VLANs
Information About VLANs
VLANs as Logically Defined Networks
Vlan Ranges
VLANs Numbers Range Usage
Creating, Deleting, and Modifying VLANs
Guidelines and Limitations for VTP
Configuring a Vlan
About the Vlan Trunking Protocol
Creating and Deleting a Vlan
Vlan vlan-id vlan-range
Configuring a Vlan
Vlan-id vlan-range
Active suspend
Switchconfig# interface ethernet
Adding Ports to a Vlan
Feature interface-vlan Enables the creation of SVIs
Configuring a Vlan as a Routed SVI
Switchconfig-if# switchport access vlan
Configure terminal Enters global configuration mode
You can configure routing protocols on this interface
Configuring a Vlan as a Management SVI
Configuring VTP
Startup-config
Vtp password
Show vtp password
Copy running-config
Summary
Verifying Vlan Configuration
Switch# show running-config vlan vlanid vlanrange
Switch# show vlan brief id vlanid vlanrange name name
Information About Private VLANs
Configuring Private VLANs
Three types of Pvlan ports are as follows
Primary and Secondary VLANs in Private VLANs
Private Vlan Ports
Primary, Isolated, and Community Private VLANs
Private Vlan Traffic Flows
Associating Primary and Secondary VLANs
Private Vlan Port Isolation
Private Vlan Promiscuous Trunks
Private Vlan Isolated Trunks
Broadcast Traffic in Private VLANs
Enabling Private VLANs
Configuring a Private Vlan
Switchconfig# feature private-vlan
Guidelines and Limitations for Private VLANs
Community isolated primary
Configuring a Vlan as a Private Vlan
Associating Secondary VLANs with a Primary Private Vlan
Association
Association add secondary-vlan-list
Remove secondary-vlan-list
Configuring an Interface as a Private Vlan Promiscuous Port
Configuring an Interface as a Private Vlan Host Port
Configuring the Allowed VLANs for Pvlan Trunking Ports
Configuring a Promiscuous Trunk Port
Configuring an Isolated Trunk Port
Switch# show interface switchport
Verifying the Private Vlan Configuration
Configuring Native 802.1Q VLANs on Private VLANs
Switch# show feature
OL-26590-01
Understanding Access and Trunk Interfaces
Configuring Access and Trunk Interfaces
Information About Access and Trunk Interfaces
Devices in a Trunking Environment
Understanding Ieee 802.1Q Encapsulation
Header without and with 802.1Q Tag Included
Understanding Access VLANs
Understanding Native 802.1Q VLANs
Understanding the Native Vlan ID for Trunk Ports
Understanding Allowed VLANs
Configuring a LAN Interface as an Ethernet Access Port
Configuring Access and Trunk Interfaces
On bpdu filtering and bpdu guard
Configuring Access Host Ports
Configuring Trunk Ports
Switchconfig-if# switchport host
Port-channel number
Configuring the Native Vlan for 802.1Q Trunking Ports
Configuring the Allowed VLANs for Trunking Ports
Specified trunk, use the switchport trunk allowed vlan
Switch# configure terminal Enters configuration mode
Configuring Native 802.1Q VLANs
Switch# show interface
Verifying Interface Configuration
Switchconfig# no vlan dot1q tag
Switch# show vlan dot1q tag native
OL-26590-01
Store-and-Forward Switching Mode
Configuring Switching Modes
Information About Switching Modes
Cut-Through Switching Mode
Store-and-Forward Switching Mode Guidelines and Limitations
Guidelines and Limitations for Switching Modes
Licensing Requirements for Switching Modes
Cut-Through Switching Mode Guidelines and Limitations
Reenabling Cut-Through Switching
Default Settings for Switching Modes
Configuring Switching Modes
Enabling Store-and-Forward Switching
Feature Name Releases Information
Feature History for Switching Modes
Saves the change persistently through reboots
This example shows how to reenable cut-through switching
STP Overview
Configuring Rapid PVST+
Information About Rapid PVST+
Understanding STP
Understanding the Bridge ID
Understanding How a Topology is Created
8192 4096 2048 1024 512 256 128
Bit extended system ID field is part of the bridge ID
Bridge Priority Value
Bit
Understanding BPDUs
Creating the Spanning Tree Topology
Election of the Root Bridge
Rapid PVST+ Overview
Understanding Rapid PVST+
Rapid PVST+ Flag Byte in Bpdu
Rapid PVST+ BPDUs
Proposal and Agreement Handshaking for Rapid Convergence
Proposal and Agreement Handshake
Variable Description
Protocol Timers
Port Roles
Rapid PVST+ Port State Overview
Port States
Blocking State
Topology?
Enabled Blocking Learning Yes Forwarding Disabled
Synchronization of Port Roles
Operational Status Port State
Processing Superior Bpdu Information
Port Cost
Spanning-Tree Dispute Mechanism
Bandwidth
Rapid PVST+ and Ieee 802.1Q Trunks
Rapid PVST+ Interoperation with Legacy 802.1D STP
Port Priority
Enabling Rapid PVST+
Configuring Rapid PVST+
Rapid PVST+ Interoperation with 802.1s MST
Terminal
Mode rapid-pvst
Switch# configure
Enabling Rapid PVST+ per Vlan
Configuring the Root Bridge ID
Spanning-tree mst max-ageconfiguration commands
Configuring a Secondary Root Bridge
Vlan vlan-list port-priority priority
Configuring the Rapid PVST+ Port Priority
Vlan vlan-id cost value auto
Configuring the Rapid PVST+ Pathcost Method and Port Cost
Configuring the Rapid PVST+ Bridge Priority of a Vlan
Pathcost method long short
Vlan-range hello-time hello-time
Configuring the Rapid PVST+ Hello Time for a Vlan
Switchconfig# spanning-tree vlan
Vlan-range forward-time forward-time
Configuring the Rapid PVST+ Forward Delay Time for a Vlan
Configuring the Rapid PVST+ Maximum Age Time for a Vlan
Specifying the Link Type
Restarting the Protocol
Verifying Rapid PVST+ Configurations
Switch# clear spanning-tree detected-protocol
Switch# show running-config spanning-tree all
This example shows how to display spanning tree status
Switch# show spanning-tree options
Spanning tree configuration
OL-26590-01
MST Overview
Configuring Multiple Spanning Tree
Information About MST
MST BPDUs
MST Regions
IST, CIST, and CST Overview
MST Configuration Information
IST, CIST, and CST
Spanning Tree Operations Between MST Regions
Spanning Tree Operation Within an MST Region
MST Regions, Cist Regional Roots, and CST Root
MST Terminology
Boundary Ports
Hop Count
MST Boundary Ports
Spanning-Tree Dispute Mechanism
Interoperability with Ieee 802.1D
Port Cost and Port Priority
Enabling MST
Configuring MST
MST Configuration Guidelines
You must enable MST Rapid PVST+ is the default
Mst configuration
Entering MST Configuration Mode
Switchconfig# spanning-tree mode mst
Switchconfig# no spanning-tree mode mst
Spanning-tree mst
Switchconfig# spanning-tree mst
Specifying the MST Name
Instance-id vlan vlan-range
Specifying the MST Configuration Revision Number
Specifying the Configuration on an MST Region
Version
Name
Mapping and Unmapping VLANs to MST Instances
Default MSTI, which is the Cist
This example shows how to map Vlan 200 to Msti
For all private VLANs
Configuring the Root Bridge
Synchronize
Same Msti and their associated primary Vlan
104
Mst instance-id root
Configuring the Port Priority
Switchconfig# no spanning-tree Optional
Configuring the Switch Priority
Configuring the Port Cost
Hello-time seconds
Configuring the Hello Time
Configures the hello time for all MST instances. The hello
Switch is alive. For seconds, the range is from 1 to 10,
Configuring the Forwarding-Delay Time
Configuring the Maximum-Aging Time
Max-hops hop-count
Configuring the Maximum-Hop Count
Configuring Pvst Simulation Globally
Mst max-age seconds
Configuring Pvst Simulation Per Port
Switchconfig-if#spanning-tree mst simulate pvst disable
Specified interfaces
Verifying MST Configurations
Restarts MST on entire switch or
Command
Understanding STP Port Types
Configuring STP Extensions
About STP Extensions
Information About STP Extensions
Understanding Bpdu Guard
Understanding Bridge Assurance
Port returns to
Is disabled
Default Enable Disable Enabled/Disabled
Understanding Bpdu Filtering
Understanding Root Guard
Understanding Loop Guard
Configuring Spanning Tree Port Types Globally
Configuring STP Extensions
STP Extensions Configuration Guidelines
Port type network default
Port type edge default
Edge ports. Edge ports immediately transition to
Switchconfig# interface type
Switchconfig-if# spanning-tree
Port type edge
Port type network
Ports. If you enable Bridge Assurance, it automatically
Enabling Bpdu Guard Globally
Enabling Bpdu Guard on Specified Interfaces
Filtering is disabled by default
Switchconfig-if# no spanning-tree bpduguard
Enables Bpdu Filtering by default on all
Edge bpdufilter default
Bpdufilter
Bpdufilter enable disable
Enabling Bpdu Filtering on Specified Interfaces
Enabling Loop Guard Globally
Loopguard default
Normal and network ports. By default, global Loop
Guard is disabled
Guard loop root none
Verifying STP Extension Configuration
126
Configuring Global Lldp Commands
Configuring Lldp
Optionalswitch# show lldp Displays Lldp configurations
Ensure that the Lldp feature is enabled on the switch
Holdtime reinit timer
Transmit
Configuring Interface Lldp Commands
This example shows how to display Lldp counters
This example shows how to display Lldp timer information
Information About MAC Addresses
Configuring the MAC Address Table
Configuring MAC Addresses
Configuring a Static MAC Address
Macaddress vlan vlan-id
Configuring the Aging Time for the MAC Table
Switchconfig-# no mac-address-table static
Switch# configure terminal Enters global configuration mode
Defined in the switch
Verifying the MAC Address Configuration
Switchconfig# clear mac-address-table dynamic
Switch# show mac-address-table aging-time
This example shows how to display the current aging time
This example shows how to display the MAC address table
Information About Igmp Snooping
Configuring Igmp Snooping
IGMPv1 and IGMPv2
Igmp Snooping Switch
Igmp Forwarding
IGMPv3
Igmp Snooping Querier
Parameter Description
Configuring Igmp Snooping Parameters
Snooping
No ip igmp snooping mrouter vpc-peer-link
No ip igmp snooping mrouter
Snooping querier IP-address
Snooping explicit-tracking
Snooping fast-leave
Last-member-query-interval
141
Verifying Igmp Snooping Configuration
142
Information About Traffic Storm Control
Configuring Traffic Storm Control
Broadcast Suppression
Traffic Storm Guidelines and Limitations
On the interface. The default state is
Configuring Traffic Storm Control
Switchconfig-if# storm-control broadcast
Configures traffic storm control for traffic
Parameters Default
Traffic Storm Control Example Configuration
Default Traffic Storm Settings
Verifying Traffic Storm Control Configuration
D E
Mstp Cist root 93 CIST, described 91 CST 91
Rstp 68, 71, 75, 89 active topology 71 Bpdu
VLANs
Adding ports to Private Configuring