ZyXEL Communications GS-4012F, User Manual

Page: 74 / 306

GS-4012F User’s Guide
Chapter 7 Basic Setting 73
7.4 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 8 on page 81 for information on port-based and 802.1Q tagged VLANs.
Use Time Server
when Bootup
Enter the time service protocol that a timeserver sends when you turn on the switch.
Not all time servers support all protocols, so you may have to use trial and error to
find a protocol that works. The main differences between them are the time format.
Daytime (RFC 867) format is day/month/year/time zone of the server.
Time (RFC-868) format displays a 4-byte integer giving the total number of seconds
since 1970/1/1 at 0:0:0.
NTP (RFC-1305) is similar to Time (RFC-868).
None is the default value. Enter the time manually. Each time you turn on the
switch, the time and date will be reset to 2000-1-1 0:0.
Time Server IP
Address
Enter the IP address (or URL if you configure a domain name server in the IP Setup
screen) of your timeserver. The switch searches for the timeserver for up to 60
seconds. If you select a timeserver that is unreachable, then this screen will appear
locked for 60 seconds. Please wait.
Current Time This field displays the time you open this menu (or refresh the menu).
New Time
(hh:min:ss)
Enter the new time in hour, minute and second format. The new time then appears
in the Current Time field after you click Apply .
Current Date This field displays the date you open this menu.
New Date (yyyy-
mm-dd)
Enter the new date in year, month and day format. The new date then appears in
the Current Date field after you click Apply .
Time Zone Select the time difference between UTC (Universal Time Coordinated, formerly
known as GMT, Greenwich Mean Time) and your time zone from the drop-down list
box.
Apply Click Apply to save the settings.
Cancel Click Cancel to reset the fields to your previous configuration.
Table 9 General Setup (continued)
LABEL DESCRIPTION