Notes About Vlans On The Des-6500; Ieee 802.1Q Vlans - D-Link DES-6500 User Manual

D-Link DES-6500 Layer 3 Stackable Gigabit Ethernet Switch
VLANs can enhance performance by conserving bandwidth, and improve security by limiting
traffic to specific domains.
A VLAN is a collection of end nodes grouped by logic instead of physical location. End nodes
that frequently communicate with each other are assigned to the same VLAN, regardless of
where they are physically on the network. Logically, a VLAN can be equated to a broadcast
domain, because broadcast packets are forwarded to only members of the VLAN on which the
broadcast was initiated.

Notes About VLANs on the DES-6500

No matter what basis is used to uniquely identify end nodes and assign these nodes VLAN
membership, packets cannot cross VLANs without a network device performing a routing
function between the VLANs.
The DES-6500 supports IEEE 802.1Q VLANs. The port untagging function can be used to
remove the 802.1Q tag from packet headers to maintain compatibility with devices that are
tag-unaware.
The Switch's default is to assign all ports to a single 802.1Q VLAN named "default."
The "default" VLAN has a VID = 1.

IEEE 802.1Q VLANs

Some relevant terms:
Tagging – The act of putting 802.1Q VLAN information into the header of a packet.
Untagging – The act of stripping 802.1Q VLAN information out of the packet header.
Ingress port – A port on a switch where packets are flowing into the switch and VLAN
decisions must be made.
Egress port – A port on a switch where packets are flowing out of the switch, either to
another switch or to an end station, and tagging decisions must be made.
IEEE 802.1Q (tagged) VLANs are implemented on the Switch. 802.1Q VLANs require
tagging, which enables them to span the entire network (assuming all switches on the network
are IEEE 802.1Q-compliant).
VLANs allow a network to be segmented in order to reduce the size of broadcast domains. All
packets entering a VLAN will only be forwarded to the stations (over IEEE 802.1Q enabled
switches) that are members of that VLAN, and this includes broadcast, multicast and unicast
packets from unknown sources.
VLANs can also provide a level of security to your network. IEEE 802.1Q VLANs will only
deliver packets between stations that are members of the VLAN.
Any port can be configured as either tagging or untagging. The untagging feature of IEEE
802.1Q VLANs allows VLANs to work with legacy switches that don't recognize VLAN tags
in packet headers. The tagging feature allows VLANs to span multiple 802.1Q-compliant
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