Tag Archives: trunk

Trunk and VLANs

A trunk is a point-to-point link between two network devices that carries more than one VLAN. A VLAN trunk allows you to extend the VLANs across an entire network.
A VLAN trunk does not belong to a specific VLAN, rather it is a conduit for VLANs between switches and routers.

Data VLAN = data VLAN is sometimes referred to as a user VLAN.

Default VLAN
The default VLAN for Cisco switches is VLAN 1. VLAN 1 has all the features of any VLAN, except that you cannot rename it and you can not delete it.
It is a security best practice to change the default VLAN to a VLAN other than VLAN 1; this entails configuring all the ports on the switch to be associated with a default VLAN other than VLAN 1.

Native VLAN=A native VLAN is assigned to an 802.1Q trunk port.

An 802.1Q trunk port supports traffic coming from many VLANs (tagged traffic) as well as traffic that does not come from a VLAN (untagged traffic).

Management VLAN=A management VLAN is any VLAN you configure to access the management capabilities of a switch.
VLAN 1 would serve as the management VLAN if you did not proactively define a unique VLAN to serve as the management VLAN. You assign the management VLAN an IP address and subnet mask.

Voice VLANs
Tagging refers to the addition of bytes to a field in the data frame which is used by the switch to identify which VLAN the data frame should be sent to.
Static VLAN
Dynamic VLAN

Voice VLAN – Before you configure a voice VLAN on the port, you need to first configure a VLAN for voice and a VLAN for data.
1-1005, and an extended range, 1006-4094
inter-switch link (ISL),
two types of trunk ports, IEEE 802.1Q and ISL, today only 802.1Q is used.

Trunking Modes
On (default)
Dynamic auto If both ports on the switches are set to auto, they do not negotiate to be in a trunking state. They negotiate to be in the access (non-trunk) mode state.
Dynamic desirable