Weidmuller Wireless Ethernet Modem & Device Server WI-MOD-E-G/A User Manual
Rev.
2.16
www.weidmuller.com
60
3.19 - Filtering
Figure 54 - Filtering
When configured as a Bridge, the WI-MOD-E will transmit all broadcast messages appearing at its wired Ethernet port.
When the WI-MOD-E is configured as a Router, this does not occur.
In many cases, the intended recipient of the broadcast traffic does not lie at the opposite end of a proposed radio link.
Reducing unnecessary broadcast traffic sent over the radio link, will increase available bandwidth for data. The WI-MOD-
E has a filtering feature to help reduce unnecessary wireless transmissions and enhance security.
The WI-MOD-E may be configured to reject or accept messages to and from certain Addresses. To accept wireless
messages from particular devices a “Whitelist” of Addresses must be made. Alternatively to reject messages from
particular devices, a “Blacklist” of Addresses must be made. Filtering applies only to messages appearing at the wired
Ethernet port of the configured WI-MOD-E.
The Filter comprises of three lists: MAC Addresses, IP Address/Protocol/Port and ARP Filters. Each list may be set as
either a Blacklist (to block traffic for listed devices and protocols), or as a Whitelist (to allow traffic for listed devices and
protocols). The Filter operates on four rules listed below.
The MAC Address filter is always checked before the IP Address filter.
If a message matches a MAC filter entry, it will not be subsequently processed by the IP filter. If the MAC filter list
is a Whitelist, the message will be accepted. If the MAC filter list is a Blacklist, the message will be dropped.
The MAC address list checks the Source address of the message only.
The IP Address filter checks both the source address and the destination address of the message. If either
address match, then the rule is activated.
ARP filtering applies only to ARP request packets (typically these are broadcast packets) which are sourced from
the Ethernet interface and destined for the wireless interface. (ARP requests from devices on the wireless network
will always be passed to the Ethernet interface. ARP response packets will always be passed).
