Table Of Contents
Configuring VLANs
Information About VLANs
Guidelines and Limitations
Maximum Allowed VLANs and MAC Addresses per VLAN
VLAN Numbering
Default Settings
Configuring a VLAN
Creating a VLAN
Configuring VLAN Characteristics
Verifying a VLAN Configuration
Additional References
Related Documents
Standards
Feature History for VLANs
Configuring VLANs
This section describes how to configure a VLAN, and includes the following topics:
•
Information About VLANs
•Guidelines and Limitations
•Default Settings
•Configuring a VLAN
•Verifying a VLAN Configuration
•Additional References
•Feature History for VLANs
Note For information about private VLANs, see Chapter 4, "Configuring a Private VLAN."
Information About VLANs
Physical NICs are always assigned as trunk ports, which transmit either VLAN tagged or untagged packets. A vswitch can have the following VLAN configurations:
Configuration
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Description
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External switch tagging (EST)
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Physical NICs are untagged and all VNICs are access ports.
EST is enabled by default and is used when the VLAN for the VNIC is set to 0 or left blank.
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Virtual switch tagging (VST)
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All physical NIC ports are tagged and VNICs are access ports.
VST is enabled whenever the VNIC's VLAN is set to any value between 1 and 4094 inclusive.
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Virtual machine guest tagging (VGT)
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All physical NIC ports are tagged. VNICs are trunk ports. To configure VGT, the VLAN is set to 4095 on the VNIC connected to the virtual machine.
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Physical ports are always trunk ports by default. The virtual machine interfaces can be either access ports or trunk ports. If a VEthernet interface is set as a trunk port, the VLAN is 4095.
VEthernet interfaces assigned to specific VLANs are tagged with the VLAN when transmitted. A VEthernet interface that is not assigned to a specific VLAN, or assigned to VLAN 0, are transmitted as untagged on the physical NIC interfaces. On the transmit side, this is equivalent to the native VLAN available in Cisco switches. When the VLAN is not specified, it is assumed to be 0.
Table 3-1 summarizes the actions taken on packets recieved by the virtual ethernet module (VEM) based on VLAN tagging.
Table 3-1 VEM Action on VLAN Tagging
Port Type
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Packet received
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Action
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Access
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Tagged
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The packet is dropped.
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Access
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Untagged
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VEM adds access VLAN to the packet.
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Trunk
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Tagged
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No action is taken on the packet.
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Trunk
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Untagged
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VEM adds native VLAN tag to packet.
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Guidelines and Limitations
This section includes the following topics:
•Maximum Allowed VLANs and MAC Addresses per VLAN
•VLAN Numbering
Maximum Allowed VLANs and MAC Addresses per VLAN
Table 3-2 lists the Cisco Nexus 1000V VLAN and MAC address limitations.
Table 3-2 Allowed VLANs and MAC Addresses per VLAN
Feature
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Maximum Limit
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Number of active VLANs
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512
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MAC addresses per VLAN within a VEM
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1024
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VLAN Numbering
In accordance with the IEEE 802.1Q standard, up to 4094 VLANs (numbered 1-4094) are supported in Cisco Nexus 1000V, and are organized as shown in Table 3-3.
Table 3-3 Cisco Nexus 1000V VLAN Numbering
VLANs Numbers
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Range
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Usage
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1
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Normal
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Cisco Nexus 1000V default. You can use this VLAN, but you cannot modify or delete it.
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2-1005
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Normal
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You can create, use, modify, and delete these VLANs.
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1006-4094
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Extended
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You can create, name, and use these VLANs. You cannot change the following parameters:
•State is always active.
•VLAN is always enabled. You cannot shut down these VLANs.
Note The extended system ID is always automatically enabled.
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3968-4047 and 4094
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Internally allocated
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You cannot use, create, delete, or modify these VLANs. You can display these VLANs.
Cisco Nexus 1000V allocates these 80 VLANs, plus VLAN 4094, for features, like diagnostics, that use internal VLANs for their operation.
|
Note For information about diagnostics, see the document,
Cisco Nexus 1000V System Management Configuration Guide, Release 4.0(4)SV1(3).
Default Settings
Table 3-4 lists the VLAN default settings.
Table 3-4 Default Private VLAN Setting
Parameters
|
Default
|
VLAN assignment for all interfaces and all ports configured as switchports
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VLAN 1
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VLAN name
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VLANxxxx where xxxx represent four numeric digits (including leading zeroes) equal to the VLAN ID number.
|
Shut state
|
No shutdown
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Operational state
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Active
|
External switch tagging (EST)
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Enabled
|
Physical ports
|
Trunk ports
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Configuring a VLAN
This section includes the following procedures for configuring a VLAN:
•Creating a VLAN
•Configuring VLAN Characteristics
Creating a VLAN
Use this procedure to do one of the following:
•Create a single VLAN that does not already exist.
•Create a range of VLANs that do not already exist.
•Delete an existing VLAN.
BEFORE YOU BEGIN
Before beginning this procedure, you must know or do the following:
Note All interfaces and all ports configured as switchports are in VLAN 1 by default.
Note Be aware that the NX-OS commands may differ from those used in Cisco IOS.
•You are logged in to the CLI in EXEC mode.
•VLAN characteristics are configured in the VLAN configuration mode. To configure a VLAN that is already created, see the procedure, Configuring VLAN Characteristics.
•You are familiar with the section, VLAN Numbering.
•Newly-created VLANs remain unused until Layer 2 ports are assigned to them.
•When you delete a specified VLAN, the ports associated to that VLAN are shut down and no traffic flows. When you delete a specified VLAN from a trunk port, only that VLAN is shut down and traffic continues to flow on all the other VLANs through the trunk port.
However, the system retains all the VLAN-to-port mapping for that VLAN, and when you reenable, or re-create, that specified VLAN, the system automatically reinstates all the original ports to that VLAN. Note that the static MAC addresses and aging time for that VLAN are not restored when the VLAN is reenabled.
•For information about the following, see the document, Cisco Nexus 1000V Interface Configuration Guide, Release 4.0(4)SV1(3).
–Assigning Layer 2 interfaces to VLANs (access or trunk ports).
–Configuring ports as VLAN access or trunk ports and assigning ports to VLANs.
SUMMARY STEPS
1. config t
2. show vlan
3. {no}vlan {vlan-id | vlan-range}
4. show vlan id <vlan-id>
5. copy running-config startup-config
DETAILED STEPS
| |
Command
|
Purpose
|
Step 1
|
config t
Example:
n1000v# config t
n1000v(config)#
|
Enters global configuration mode.
|
Step 2
|
show vlan
Example:
n1000v(config)# show vlan
|
Displays the VLANs that already exist.
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Step 3
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{no} vlan {vlan-id | vlan-range}
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Creates or deletes, and saves in the running configuration, a VLAN or a range or VLANs.
To configure the VLAN, see the procedure, Configuring VLAN Characteristics.
Note If you enter a VLAN ID that is already assigned, you are placed into the VLAN configuration mode for that VLAN.
Note If you enter a VLAN ID that is assigned to an internally allocated VLAN, the system returns an error message.
Note From the VLAN configuration mode, you can also create and delete VLANs.
|
| |
Example:
n1000v(config)# vlan 5
n1000v(config-vlan)#
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In this example VLAN 5 is created and you are automatically placed into the VLAN configuration mode for VLAN 5.
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| |
Example:
n1000v(config)# vlan 15-20
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This example shows the range, VLAN 15-20, being created.
The VLANs in the range are activated, and you are automatically placed into VLAN configuration mode for VLANs 15-20.
Note If you create a range of VLANs that includes an unusable VLAN, all VLANs in the range are created except those that are unusable; and Cisco Nexus 1000V returns a message listing the failed VLANs.
|
| |
Example:
n1000v(config)# no vlan 3967
n1000v(config)#
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This example shows VLAN 3967 being deleted, using the no form of the command.
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Step 4
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show vlan id 5
Example:
n1000v(config-vlan)# show vlan id 5
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(Optional) Displays the VLAN configuration.
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Step 5
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copy running-config startup-config
Example:
n1000v(config-vlan)# copy running-config
startup-config
|
(Optional) Saves the running configuration persistently through reboots and restarts by copying it to the startup configuration.
|
n1000v(config-vlan)# show vlan id 5
---- -------------------------------- --------- -------------------------------
Primary Secondary Type Ports
------- --------- --------------- -------------------------------------------
n1000v(config-vlan)# copy run start
[########################################] 100%
Configuring VLAN Characteristics
Use this procedure to configure the following for a VLAN that has already been created:
•Name the VLAN.
•The operational state (active, suspend) of the VLAN.
•The VLAN media type (Ethernet).
•Shut down switching on the VLAN.
BEFORE YOU BEGIN
Before beginning this procedure, you must know or do the following:
•Some characteristics cannot be modified on some VLANs. For more information, see the "VLAN Numbering" section.
Note Commands entered in the VLAN configuration mode are immediately saved to the running configuration.
SUMMARY STEPS
1. config t
2. vlan {vlan-id | vlan-range}
3. name vlan-name
4. state {active | suspend}
5. no shutdown
6. show vlan id
7. copy running-config startup-config
DETAILED STEPS
| |
Command
|
Purpose
|
Step 1
|
config t
Example:
n1000v# config t
n1000v(config)#
|
Enters global configuration mode.
|
Step 2
|
vlan {vlan-id | vlan-range}
Example:
n1000v(config)# vlan 5
n1000v(config-vlan)#
|
Enters VLAN configuration mode for the specified VLAN.
Note If the VLAN does not already exist, the system creates it and then enters the VLAN configuration mode for that VLAN.
|
Step 3
|
name vlan-name
Example:
n1000v(config-vlan)# name accounting
n1000v(config-vlan)#
|
Adds a name to the VLAN of up to 32 alphanumeric characters..
•You cannot change the name of VLAN1 nor the VLANs reserved for internal use.
•The default name is VLANxxxx where xxxx represent four numeric digits (including leading zeroes) equal to the VLAN ID number.
|
Step 4
|
state {active | suspend}
Example:
n1000v(config-vlan)# state active
n1000v(config-vlan)#
|
Changes the operational state of the VLAN and saves it in the running configuration.
Allowable entries are:
•Active (default)
•Suspend
While the VLAN state is suspended, the ports associated with this VLAN are shut down, and that VLAN does not pass any traffic.
Note You cannot suspend the state for the default VLAN or VLANs 1006 to 4094.
|
Step 5
|
no shutdown
Example:
n1000v(config-vlan)# no shutdown
n1000v(config-vlan)#
|
Enables VLAN switching in the running configuration.
Allowable entries are:
•no shutdown (default)
•shutdown
Note You cannot shut down the default VLAN, VLAN1, or VLANs 1006 to 4094.
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Step 6
|
show vlan [id <vlan-id>]
Example:
n1000v(config-vlan)# show vlan id 5
n1000v(config-vlan)#
|
(Optional) Displays the VLAN configuration.
|
Step 7
|
copy running-config startup-config
Example:
n1000v(config-vlan)# copy running-config
startup-config
n1000v(config-vlan)#
|
(Optional) Saves the running configuration persistently through reboots and restarts by copying it to the startup configuration.
|
n1000v(config-vlan)# name accounting
n1000v(config-vlan)# state active
n1000v(config-vlan)# no shutdown
n1000v(config-vlan)# show vlan brief
---- -------------------------------- --------- -------------------------------
1 default active Eth2/1, Eth2/2, Eth2/3, Eth2/5
Eth2/7, Eth2/8, Eth2/9, Eth2/10
Eth2/15, Eth2/21, Eth2/22
Eth2/23, Eth2/24, Eth2/25
Eth2/46, Eth2/47, Eth2/48
50 VLAN0050 active Eth2/6
Verifying a VLAN Configuration
Use the following commands to display and verify a VLAN configuration.
Command
|
Purpose
|
show running-config vlan <vlan-id>
|
Displays VLAN information in the running configuration.
|
show vlan [all-ports | brief | id <vlan-id> | name <name> | dot1q tag native]
|
Displays the specified VLAN information.
|
show vlan summary
|
Displays a summary of VLAN information.
|
Example 3-1 show vlan summary
n1000v(config)# show vlan summary
Number of existing VLANs : 13
Number of existing user VLANs : 12
Number of existing extended VLANs : 1
Example 3-2 show vlan brief
n1000v(config)# show vlan brief
---- -------------------------------- --------- -------------------------------
1 default active Eth2/1, Eth2/2, Eth2/3, Eth2/5
Eth2/7, Eth2/8, Eth2/9, Eth2/10
Eth2/15, Eth2/21, Eth2/22
Eth2/23, Eth2/24, Eth2/25
Eth2/46, Eth2/47, Eth2/48
50 VLAN0050 active Eth2/6
Additional References
For additional information related to implementing VLANs, see the following sections:
•Related Documents
•Standards
Related Documents
Related Topic
|
Document Title
|
Private VLANs
|
Chapter 4, "Configuring a Private VLAN."
|
Interfaces, VLAN interfaces (SVIs), IP addressing and port channels
|
Cisco Nexus 1000V Interface Configuration Guide, Release 4.0(4)SV1(3)
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Getting Started with Cisco Nexus 1000V and the CLI
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Cisco Nexus 1000V Getting Started Guide, Release 4.0(4)SV1(3)
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System management
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Cisco Nexus 1000V System Management Configuration Guide, Release 4.0(4)SV1(3)
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Release notes
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Cisco Nexus 1000V Release Notes, Release 4.0(4)SV1(3)
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Complete command syntax, command modes, command history, defaults, usage guidelines, and examples
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Cisco Nexus 1000V Command Reference, Release 4.0(4)SV1(3)
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Standards
Standards
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Title
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.
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—
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Feature History for VLANs
This section provides the release history for the VLAN feature.
Table 3-5
Feature Name
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Releases
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Feature Information
|
VLANs
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4.0(4)SV1(1)
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This feature was introduced.
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