www.elpro.com.au
245U-E Wireless Ethernet Modem User Manual
73
Rev Version 2.24
Configuration.” DNS is the system that translates Internet names (such as www.Elpro.com/wireless) to IP
addresses. The ELPRO 245U-E can act as a DNS server for a local network. Name to IP address mapping is
automatically updated by the built-in DHCP server when it issues an IP address to a client unit.
For the DNS server configuration to be effective, each DNS client must be configured with the address
of this DNS server, as either the primary or secondary DNS (secondary DNS is only used if there is no
response from the primary DNS). Normally, this is done by setting the primary DNS field of the DHCP server
configuration to the wireless IP address. This address is then provided to client units to use as their primary
DNS server address when the DHCP server issues an IP address. The DNS server is configured using the
following settings.
Enabled
Select this checkbox to enable the DNS server.
Domain Name
This is a common suffix applied to the name of each device in the network.
If your network is part of a larger network, this would be assigned to you by
the relevant naming authority. If your network is stand-alone, this field is set
to an arbitrary name of your choice.
Device Name (Host
Name)
This is the DNS name of the local device (commonly referred to as the host
name or computer name). This setting is duplicated on the main Module
Information configuration page. This is the name which is used to refer to
this device (see “3.24 Module Information”).
3.23 VLAN
What is VLAN
Virtual Local Area Network (VLAN) is a way of splitting a network into groups that could extend beyond a
single traditional LAN to groups of LANs, each identified with a different VLAN ID (VID). Using a VLAN, you
can group users by logical connections instead of physical location. This can increase security and help
improve the efficiency of traffic flow by limiting multicast and broadcast messages. Traffic between VLANs is
blocked unless the VLAN is identified with the correct VLAN ID.
There are three main VLAN modes that the 245U-E supports:
• VLAN (Pass-through Mode)—A transparent bridge in which frames are forwarded unmodified. This is
the default mode of the modem in which all frames pass transparently through the bridge regardless
of whether they are VLAN tagged or untagged. This is the most common VLAN mode and requires no
VLAN configuration at all. In VLAN Pass-through mode, access to the internal management functions is
via untagged frames only, using the IP address and subnet mask configured on the Network page.
• VLAN Aware (Bridging Mode)—A VLAN bridge that allows only explicitly configured VLANs that
correspond to the configured VLAN groups to pass data. VLAN Bridging mode is used when the
tagging method is changed in a bridged network, for example, if a frame traverses from a VLAN
group to an interface that is not configured in a VLAN. When a VLAN packet is passed to an untagged
VLAN interface, the tag is removed so that the packet can properly enter the network. Likewise, if an
untagged VLAN packet is passed to a VLAN group a VLAN tag is added. When one or more VLAN groups
have been configured, VLAN Pass-through is disabled and VLAN Aware mode is enabled.
• VLAN Aware (Routing Mode)—Same as VLAN Aware (Bridging Mode) described above, except that
VLANs are routed not bridged. When a packet is routed from one VLAN to another on a different
interface. The interfaces can be tagged or untagged and are generally on different subnets.