Reference Guide

Virtual LANs
VLANs segment a single at L2 broadcast domain into multiple logical L2 networks. Each VLAN is uniquely identied by a VLAN ID or tag
consisting of 12 bits in the Ethernet frame. VLAN IDs range from 1 to 4093 and can provide a total of 4093 logical networks.
You can assign ports on a single physical device to one or more VLANs creating multiple logical instances on a single physical device. The
virtual logical switches spanning across dierent physical devices emulate multiple logically segmented L2 networks on a single physical
network.
Each VLAN has its own broadcast domain and the unicast, multicast, and broadcast network trac from ports that belong to a VLAN is
forwarded or ooded to ports in the same VLAN only. Trac between VLANs must be routed from one VLAN to another. You can also
assign each VLAN an IP address to group all the ports within a single IP subnet.
Segment a L2 network using VLANs to:
• Minimize broadcast and multicast trac in the L2 network
• Increase security by isolating ports into dierent VLANs
• Ease network management
Default VLAN
All interface ports are administratively up (in L2 mode) and are automatically placed in the default VLAN as untagged interfaces.
When you assign a port to a non-default VLAN in Trunk mode, the interface remains an untagged member of the default VLAN and a
tagged member of the new VLAN. When you assign a port to a non-default VLAN in Access mode, it removes from the default VLAN and
is assigned to the new VLAN as an untagged member of the new VLAN.
• VLAN 1 is the default VLAN.
• You cannot delete the default VLAN. However, you can change the default VLAN ID number using the default vlan-id command.
Use the show vlan command to verify that the interface is part of the default VLAN (VLAN 1).
Default VLAN conguration
OS10# show vlan
Codes: * - Default VLAN, G-GVRP VLANs, R-Remote Port Mirroring VLANs, P-Primary, C-Community, I-
Isolated
Q: A-Access (Untagged), T-Tagged
x-Dot1x untagged, X-Dot1x tagged
G-GVRP tagged, M-Vlan-stack, H-VSN tagged
i-Internal untagged, I-Internal tagged, v-VLT untagged, V-VLT tagged
NUM Status Description Q Ports
* 1 up A Eth1/1/1-1/1/54
Create or remove VLANs
You can create VLANs and add physical interfaces or port-channel (LAG) interfaces to the VLAN as tagged or untagged members. You can
add an Ethernet interface as a trunk port or as an access port, but it cannot be added as both at the same time.
Multiple non-default vlans with physical and port channel ports in access and trunk modes
OS10# show vlan
Codes: * - Default VLAN, G-GVRP VLANs, R-Remote Port Mirroring VLANs, P-Primary, C-Community, I-
Isolated
Layer 2
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