Netgear GS724TS-100NAS User Manual download pdf (Page 250)

250 | Appendix B: Configuration Examples

GS716Tv2 and GS724Tv3 Software Administration Manual

Virtual Local Area Networks (VLANs)

A local area network (LAN) can generally be defined as a broadcast domain. Hubs, bridges,

or switches in the same physical segment or segments connect all end node devices. End

nodes can communicate with each other without the need for a router. Routers connect LANs

together, routing the traffic to the appropriate port.

A virtual LAN (VLAN) is a local area network with a definition that maps workstations on some

basis other than geographic location (for example, by department, type of user, or primary

application). To enable traffic to flow between VLANs, traffic must go through a router, just as

if the VLANs were on two separate LANs.

A VLAN is a group of PCs, servers, and other network resources that behave as if they were

connected to a single network segment—even though they might not be. For example, all

marketing personnel might be spread throughout a building. Yet if they are all assigned to a

single VLAN, they can share resources and bandwidth as if they were connected to the same

segment. The resources of other departments can be invisible to the marketing VLAN

members, accessible to all, or accessible only to specified individuals, depending on how the

IT manager has set up the VLANs.

VLANs have a number of advantages:

• It is easy to do network segmentation. Users that communicate most frequently with each

other can be grouped into common VLANs, regardless of physical location. Each group’s

traffic is contained largely within the VLAN, reducing extraneous traffic and improving the

efficiency of the whole network.

• They are easy to manage. The addition of nodes, as well as moves and other changes,

can be dealt with quickly and conveniently from a management interface rather than from

the wiring closet.

• They provide increased performance. VLANs free up bandwidth by limiting node-to-node

and broadcast traffic throughout the network.

• They ensure enhanced network security. VLANs create virtual boundaries that can be

crossed only through a router. So standard, router-based security measures can be used

to restrict access to each VLAN.

Packets received by the switch are treated in the following way:

• When an untagged packet enters a port, it is automatically tagged with the port’s default

VLAN ID tag number. Each port has a default VLAN ID setting that is user configurable

(the default setting is 1). The default VLAN ID setting for each port can be changed in the

Port PVID Configuration screen. See Port VLAN ID Configuration on page 83.

• When a tagged packet enters a port, the tag for that packet is unaffected by the default

VLAN ID setting. The packet proceeds to the VLAN specified by its VLAN ID tag number.

• If the port through which the packet entered does not have membership with the VLAN

specified by the VLAN ID tag, the packet is dropped.

• If the port is a member of the VLAN specified by the packet’s VLAN ID, the packet can be

sent to other ports with the same VLAN ID.

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Netgear GS724TS-100NAS User Manual Page 250