ZyXEL Communications IES-2000, User Manual

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IES-2000/3000 User’s Guide
General, Switch and IP Setup 19-5
VLAN Tag Control Tagged Ports tag all (VLAN member) egress frames transmitted.
Untagged Ports do not tag all (VLAN member) egress frames
transmitted.
VLAN Port Port VID This is the VLAN ID assigned to untagged frames that this port
receives.
Acceptable Frame
Type
Whether tagged only or both untagged frames are accepted
on this port.
Ingress Filtering If set, the device discards incoming frames for VLANs which
do not include this port in its member set.
19.2.6 VLANs
A VLAN (Virtual Local Area Network) allows a physical network to be partitioned into multiple logical
networks. Stations on a logical network belong to one group. A station can belong to more than one group. With
VLAN, a station cannot directly talk to or hear from stations that are not in the same group(s); the traffic must first
go through a router.
In MTU 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.
VLANs also increase 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, broadcasts are confined to the members of the VLAN. Note that VLANs are unidirectional -
they only govern outgoing traffic.
Port-based VLANS
Port-based VLANs are VLANs where the packet forwarding decision is based on the destination MAC address
and its associated port.
As previously mentioned, VLANs are unidirectional. Therefore, if you wish to allow two subscriber ports to talk
to each other, for example, between conference rooms in a hotel, you must define the egress (an egress port is an
outgoing port, that is, a port through which a data packet leaves) for both ports.
Port-based VLANs are specific only to the switch on which they were created. The factory default port-based
VLAN settings for VLC1012 are summarized below.
•
Port 0 (the CPU management port) forms a VLAN with uplink ports and can use all Ethernet ports as the
uplink.
•
The VDSL ports cannot talk to each other.
•
Each VDSL port forms a VLAN with the Ethernet ports and vice-versa.