ZyXEL Communications metrogigabit switch manual Introduction to VLANs, 104

Chapter 8 Basic Setting

Table 10	Basic Setting > General Setup (continued)
LABEL		DESCRIPTION
End Date		Configure the day and time when Daylight Saving Time ends if you
		selected Daylight Saving Time. The time field uses the 24 hour
		format. Here are a couple of examples:
		Daylight Saving Time ends in the United States on the first Sunday of
		November. Each time zone in the United States stops using Daylight
		Saving Time at 2 A.M. local time. So in the United States you would
		select First, Sunday, November and 2:00.
		Daylight Saving Time ends in the European Union on the last Sunday of
		October. All of the time zones in the European Union stop using Daylight
		Saving Time at the same moment (1 A.M. GMT or UTC). So in the
		European Union you would select Last, Sunday, October and the last
		field depends on your time zone. In Germany for instance, you would
		select 2:00 because Germany's time zone is one hour ahead of GMT or
		UTC (GMT+1).
Apply		Click Apply to save your changes to the Switch’s run-time memory. The
		Switch loses these changes if it is turned off or loses power, so use the
		Save link on the top navigation panel to save your changes to the non-
		volatile memory when you are done configuring.
Cancel		Click Cancel to begin configuring this screen afresh.

8.4 Introduction to VLANs

A VLAN (Virtual Local Area Network) allows a physical network to be partitioned into multiple logical networks. Devices on a logical network belong to one group. A device can belong to more than one group. With VLAN, a device cannot directly talk to or hear from devices that are not in the same group(s); the traffic must first go through a router.

In MTU (Multi-Tenant Unit) applications, VLAN is vital in providing isolation and security among the subscribers. When properly configured, VLAN prevents one subscriber from accessing the network resources of another on the same LAN, thus a user will not see the printers and hard disks of another user in the same building.

VLAN also increases network performance by limiting broadcasts to a smaller and more manageable logical broadcast domain. In traditional switched environments, all broadcast packets go to each and every individual port. With VLAN, all broadcasts are confined to a specific broadcast domain.

Note: VLAN is unidirectional; it only governs outgoing traffic.

See Chapter 9 on page 117 for information on port-based and 802.1Q tagged VLANs.

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MGS3700-12C User’s Guide