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This chapter contains the following sections:
Physical NICs are always assigned as trunk ports that transmit either VLAN tagged or untagged packets. A vswitch can have the following VLAN configurations:
Configuration | Description |
---|---|
External Switch Tagging (EST) |
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. |
Virtual Switch Tagging (VST) |
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. |
Virtual Machine Guest Tagging (VGT) |
All physical NIC ports are tagged. vNICs are trunk ports. To configure VGT, the VLAN is set to 4095 on the vNIC that is connected to the Virtual Machine (VM). |
Physical ports are always trunk ports by default. The VM interfaces can be either access ports or trunk ports.
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
In Cisco Nexus 1000V for Microsoft Hyper-V, a VLAN is not created to define a bridge domain. Instead, a network segment is created on the virtual supervisor module (VSM). The network segment creation triggers the auto-creation of VLANs. Refer to the Cisco Nexus 1000V for Microsoft Hyper-V Network Segmentation Manager Configuration Guide for more about the VLAN configuration process.
Refer to the Cisco Nexus 1000V for Microsoft Hyper-V Network Segmentation Manager Configuration Guide for more information about the VLAN configuration process.
Use one of 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. |
switch# show vlan summary Number of existing VLANs : 13 Number of existing user VLANs : 12 Number of existing extended VLANs : 1 switch#
switch# 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#
Feature Name |
Releases |
Feature Information |
---|---|---|
VLANs |
5.2(1)SM1(5.1) |
This feature was introduced |