VLAN Configuration

VLAN（Virtual Local Area Network）The commands for creating, deleting and adding members are shown in the table.

show vlan summary

[Command]

show vlan summary

[Purpose]

Display VLAN summary information

[View]

System view

[Use Cases]

sonic# show vlan summary
+-----------+----------------+-----------+----------------+---------------------+
| VLAN ID   | IP Address     | Ports     | Port Tagging   | DHCP Helper Address |
+===========+================+===========+================+=====================+
| 1000      | 192.168.0.1/21 | Ethernet0 | untagged       | 192.0.0.1           |
|           |                | Ethernet1 | untagged       | 192.0.0.2           |
|           |                | Ethernet2 | untagged       | 192.0.0.3           |
|           |                | Ethernet3 | untagged       | 192.0.0.4           |
+-----------+----------------+-----------+----------------+---------------------+

Description of the show vlan summary command output

Item	Description
VLAN ID	VLAN ID
IP address	IP address for SVI interface
Ports	VLAN member interface
Port Tagging	VLAN member interface properties
DHCP Helper Address	If the device has DHCP relay enabled and this VLAN is added as a downlink interface to a DHCP instance, then this section displays the DHCP Server IP address for that instance.

show vlan vid

[Command]

show vlan vid vlan_id

show vlan all

[Purpose]

Display VLAN specific information

[View]

System view

[Use Cases]

sonic# show vlan vid 300
VLAN ID: 300
Route interface:
Name: VLAN 300
Tagged ports:
Untagged ports:
  Ethernet1
MAC-learning: enable

vlan

[Command]

vlan vlan_id

no vlan vlan_id

[Purpose]

Create VLAN

[Parameter]

Parameter	Description
vlan-id	vid(1-4094)

[View]

System configuration view

[Use Cases]

sonic# configure terminal
sonic(config)# vlan 300
sonic(config-vlan-300)# show this
!
vlan 300

switchport {trunk|access} vlan

[Command]

switchport {trunk|access} vlan vlan_id

[Purpose]

Add interface to VLAN

[Parameter]

Parameter	Description
trunk	Add interface to VLAN with trunk mode
access	Add interface to VLAN with access mode

[View]

Interface view

[Usage Scenario]

Frames sent by user hosts are untagged, and frames received by the interface from the peer device may be tagged. Therefore, the device should be configured with different modes when adding interfaces to VLANs, depending on the actual use case.

[Comment]

Access Mode: An interface can only be added to one VLAN in access mode. When an interface is added to a VLAN in access mode, as an incoming interface, it can receive frames without VLAN tags or with VLAN IDs equal to the access value. As an outgoing interface, it compares the VLAN tag carried by the frame with the access value. If they are equal, it strips the VLAN tag from the frame; if they are not equal, it takes no action.
Trunk Mode: An interface can be added to multiple VLANs in trunk mode, indicating that it allows traffic to pass through without modifying the VLAN tag on the frame. A physical interface can be added to different VLANs in both access and trunk modes.

[Use Cases]

sonic(config)# interface ethernet 1
sonic(config-if-1)# switchport access vlan 10

vlan-group

[Command]

vlan-group vlan_id - vlan_id

[Purpose]

Bulk create VLANs and enter VLAN configuration view

[Parameter]

Parameter	Description
vlan_id - vlan_id	Specify the VLAN range

[View]

System configuration view

[Usage Scenario]

When there is a need to configure a large number of VLANs with similar properties, this command allows entering the VLAN creation process and VLAN configuration view for modifying the configuration of these VLANs.

[Use Cases]

sonic(config)# vlan-group 10-20,30,40

broadcast {flood|drop}

[Command]

broadcast {flood|drop}

[Purpose]

Configure broadcast function handling

[Parameter]

Parameter	Description
flood	Broadcast packets within a VLAN
drop	Drop broadcast packets

[View]

VLAN view

[Usage Scenario]

Broadcast forwarding is a method of sending a data packet to all devices within the same VLAN. It can be used for sending ARP requests, DHCP requests, and similar functions. In a VLAN, whether broadcast packets are forwarded can be configured on the switch.

[Use Cases]

sonic# configure terminal
sonic(config)# vlan 40
sonic(config-vlan-40)# broadcast drop

unknown-uni {flood|drop}

[Command]

unknown-uni {flood|drop}

[Purpose]

Configure the processing of unknown unicast packets

[Parameter]

Parameter	Description
flood	Broadcast packets within a VLAN
drop	Drop unknown unicast packets

[View]

VLAN view

[Usage Scenario]

Unknown unicast refers to unicast data packets for which the switch cannot determine the VLAN in which the destination MAC address resides. If a VLAN needs to receive unknown unicast data, it can be configured in unknown unicast forwarding mode. If a VLAN does not need to forward unknown unicast data packets within it, it can be configured in discard mode.

[Use Cases]

sonic# configure terminal
sonic(config)# vlan 40
sonic(config-vlan-40)# unknown-uni drop

unre-multi {flood|drop}

[Command]

unre-multi {flood|drop}

[Purpose]

Configure the processing of unknown multicast packets

[Parameter]

Parameter	Description
flood	Broadcast packets within a VLAN
drop	Drop unknown multicast packets

[View]

VLAN view

[Usage Scenario]

Multicast is a method of sending packets to a group of devices in the same VLAN. It is used for multimedia streaming, routing protocols, and more. In a VLAN, multicast forwarding can be achieved by configuring the switch’s IGMP snooping feature. However, if you want to prevent the forwarding of unknown multicast within that VLAN, you can use the “drop” parameter for implementation.

[Use Cases]

sonic# configure terminal
sonic(config)# vlan 40
sonic(config-vlan-40)# unre-multi drop