PLANET FGSD-1022 - Manual (Page 70)

User’s Manual of FGSD-1022 Series
4.4 VLAN configuration
4.4.1 VLAN Overview
A Virtual Local Area Network (VLAN) is a network topology configured according to a logical scheme rather than the
physical layout. VLAN can be used to combine any collection of LAN segments into an autonomous user group that
appears as a single LAN. VLAN also logically segment the network into different broadcast domains so that packets are
forwarded only between ports within the VLAN. Typically, a VLAN corresponds to a particular subnet, although not
necessarily.
VLAN 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.
1. No matter what basis is used to uniquely identify end nodes and assign these nodes VLAN
membership, packets cannot cross VLAN without a network device performing a routing
function between the VLAN.
2. The Managed Switch supports IEEE 802.1Q VLAN. The port untagging function can be used
to remove the 802.1 tag from packet headers to maintain compatibility with devices that are
tag-unaware.
The Managed Switch supports IEEE 802.1Q (tagged-based) and Port-Base VLAN setting in web management page. In
the default configuration, VLAN support is “802.1Q”.
 Port-based VLAN
Port-based VLAN limit traffic that flows into and out of switch ports. Thus, all devices connected to a port are members of
the VLAN(s) the port belongs to, whether there is a single computer directly connected to a switch, or an entire department.
On port-based VLAN.NIC do not need to be able to identify 802.1Q tags in packet headers. NIC send and receive normal
Ethernet packets. If the packet’s destination lies on the same segment, communications take place using normal Ethernet
protocols. Even though this is always the case, when the destination for a packet lies on another switch port, VLAN
considerations come into play to decide if the packet is dropped by the Managed Switch or delivered.
 IEEE 802.1Q VLANs
IEEE 802.1Q (tagged) VLAN are implemented on the Managed Switch. 802.1Q VLAN require tagging, which enables them
to span the entire network (assuming all switches on the network are IEEE 802.1Q-compliant).
VLAN 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.
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