Administrator Guide

704 VLANs
Table 21-1 provides an overview of the types of VLANs that can be used to
logically divide the network.
VLAN Tagging
Dell Networking N-Series switches support IEEE 802.1Q tagging. Ethernet
frames on a tagged VLAN have a 4-byte VLAN tag in the header. VLAN
tagging is required when a VLAN spans multiple switches, which is why trunk
ports transmit and receive only tagged frames.
Tagging may be required when a single port supports multiple devices that are
members of different VLANs. For example, a single port might be connected
to an IP phone, a PC, and a printer (the PC and printer are connected via
ports on the IP phone). IP phones are typically configured to use a tagged
VLAN for voice traffic, while the PC and printers typically use the untagged
VLAN.
Table 21-1. VLAN Assignment
VLAN Assignment Description
Port-based (Static) This is the most common way to assign hosts to VLANs.
The port where the traffic enters the switch determines the
VLAN membership.
IP Subnet Hosts are assigned to a VLAN based on their IP address. All
hosts in the same subnet are members of the same VLAN.
MAC-Based The MAC address of the device determines the VLAN
assignment. This type of VLAN is useful when a host
might not always connect to the network through the same
port but needs to be on the same VLAN.
Protocol Protocol-based VLANs were developed to separate traffic
based on the layer-2 Ethertype before IP traffic became the
de facto standard in the LAN. Use a protocol-based VLAN
on networks where you might have a group of hosts that
use IPX or another legacy protocol. With protocol-based
VLANs, traffic can be segregated based on the EtherType
value in the frame.
NOTE: A stack of switches behaves as a single switch, so VLAN tagging is not
required for packets traversing different stack members.