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This chapter contains the following sections:
vEthernet interfaces that are 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, is transmitted as untagged on the physical NIC interfaces. When the VLAN is not specified, it is assumed to be 1.
The following table summarizes the actions taken on packets that are received by the Virtual Ethernet Module (VEM) based on VLAN tagging.
Port Type | Packet received | Action |
---|---|---|
Access |
Tagged |
The packet is dropped. |
Access |
Untagged |
The VEM adds an access VLAN to the packet. |
Trunk |
Tagged |
No action is taken on the packet. |
Trunk |
Untagged |
The VEM adds a native VLAN tag to the packet. |
In accordance with the IEEE 802.1Q standard, up to 4094 VLANs (from 1 to 4094) are supported in the Cisco Nexus 1000V, and are listed in the following table.
Note | For VLAN configuration limits, see Layer 2 Switching Configuration Limits. |
VLAN Numbers | Range | Usage |
---|---|---|
1 |
Normal |
Cisco Nexus 1000V default. You can use this VLAN, but you cannot modify or delete it. |
2 to1005 |
Normal |
You can create, use, modify, or delete these VLANs. |
1006 to 4094 |
Extended |
You can create, name, or use these VLANs. You cannot change the following parameters: The extended system ID is always automatically enabled. |
3968 to 4047 and 4094 |
Internally allocated |
You cannot use, create, delete, or modify these VLANs. You can display these VLANs. The Cisco Nexus 1000V allocates these 80 VLANs, plus VLAN 4094, for features, like diagnostics, that use internal VLANs for their operation. |
Parameters | Default |
---|---|
VLAN assignment for all interfaces and all ports configured as switchports |
VLAN 1 |
VLAN name |
VLANxxxx where xxxx represent four numeric digits (including leading zeroes) equal to the VLAN ID number |
Shut state |
No shutdown |
Operational state |
Active |
External Switch Tagging (EST) |
Enabled |
Physical ports |
Trunk ports |
IGMP snooping |
Enabled |
Configuring a VLAN
You can do one of the following:
Create a single VLAN that does not already exist.
Create a range of VLANs that does not already exist.
Delete an existing VLAN.
Note | All interfaces and all ports configured as switchports are in VLAN 1 by default. |
Log in to the CLI in EXEC mode.
Know that VLAN characteristics are configured in the VLAN configuration mode. To configure a VLAN that is already created, see Configuring VLAN Characteristics.
Be familiar with the VLAN numbering in the Guidelines and Limitations.
Know that newly created VLANs remain unused until Layer 2 ports are assigned to them.
Know that 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.
Note | Be aware that the Cisco NX-OS commands may differ from those commands used in Cisco IOS. |
Command or Action | Purpose | |||
---|---|---|---|---|
Step 1 | switch# configure terminal |
Enters global configuration mode. | ||
Step 2 | switch(config)# show vlan |
Displays the VLANs that already exist. | ||
Step 3 | switch(config)# [no] vlan {vlan-id | vlan-range} |
Creates or deletes, and saves in the running configuration, a VLAN or a range or VLANs. To configure the VLAN, see Configuring VLAN Characteristics.
For information about Assigning Layer 2 interfaces to VLANs (access or trunk ports), see the Cisco Nexus 1000V Interface Configuration Guide. For information about configuring ports as VLAN access or trunk ports and assigning ports to VLANs, see the Cisco Nexus 1000V Interface Configuration Guide. | ||
Step 4 | switch(config-vlan)# show vlan id vlan-id | (Optional)
Displays the VLAN configuration. | ||
Step 5 | switch(config-vlan)# copy running-config startup-config | (Optional)
Saves the running configuration persistently through reboots and restarts by copying it to the startup configuration. |
In this example, VLAN 5 is created and you are automatically placed into the VLAN configuration mode for VLAN 5:
switch# configure terminal switch(config)# vlan 5 switch(config-vlan)#
This example shows the range, VLAN 15 to 20, being created. The VLANs in the range are activated, and you are automatically placed into VLAN configuration mode for VLANs 15 to 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. |
switch# configure terminal switch(config)# vlan 15-20 switch(config-vlan)#
This example shows how to delete VLAN 3967:
switch# configure terminal switch(config)# no vlan 3967 switch(config)#
This example shows how to display the VLAN 5 configuration:
switch# configure terminal switch(config)# vlan 5 switch(config-vlan)# show vlan id 5 VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 5 VLAN0005 active VLAN Type ---- ----- 5 enet Remote SPAN VLAN ---------------- Disabled Primary Secondary Type Ports ------- --------- --------------- ------------------------------------------- n1000v(config-vlan)# copy run start [########################################] 100% n1000v(config)#
You can do the following for a VLAN that has already been created:
Note | Commands entered in the VLAN configuration mode are immediately saved to the running configuration. |
Note | Some characteristics cannot be modified on some VLANs. For more information, see the VLAN numbering described in the Guidelines and Limitations. |
This example shows how to configure VLAN characteristics:
switch# configure terminal
switch(config)# vlan 5
switch(config-vlan)# name accounting
switch(config-vlan)# state active
switch(config-vlan)# no shutdown
switch(config-vlan)# exit
switch(config)# show vlan brief
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
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
5 accounting active
6 VLAN0006 active
7 VLAN0007 active
8 test active
9 VLAN0009 active
10 VLAN0010 active
50 VLAN0050 active Eth2/6
100 trunked active
200 VLAN0200 active
201 VLAN0201 active
202 VLAN0202 active
3966 VLAN3966 active
switch(config)#
Use the following commands to verify the 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. |
Feature Name |
Feature Name |
Releases |
---|---|---|
VLANs |
4.0(4)SV1(1) |
This feature was introduced. |