3Com PathBuilder S200 Series, Owner'S Manual

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54 Bridging
Transparent Bridging for Ethernet LANs
Using Filters
Support
The Forwarder provides its own filtering facility which is used to reduce unnecessary
traffic and to provide security. The filtering facility supports the following types of
filters:
• Incoming Source Address Filter
• Incoming Destination Address Filter
• Outgoing Source Address Filter
• Outgoing Destination Address Filter
Incoming Source
Address Filter
The Incoming Source Address Filter filters packets are based on their source address
and incoming links. Frames with a source address found in the Incoming Source
Address Filter List are discarded without applying bridge logic. This filter may be
applied to all links or selected links.
Incoming
Destination
Address Filter
The Incoming Destination Address Filter filters packets based on their destination
address and the incoming ports. Frames with a destination address found in the
Incoming Destination Address Filter List are discarded without applying bridge
logic. This filter may be applied to all links or selected links.
Outgoing Source
Address Filter
The Outgoing Source Address Filter filters packets based on their source address and
the outgoing links. Frames with a source address found in the Outgoing
Source Address Filter List are discarded. This filter may be applied to all links or
selected links.
Outgoing
Destination
Address Filter
The Outgoing Destination Address Filter filters packets based on their destination
address and the outgoing links. Frames with a destination address found in the
Outgoing Destination Address Filter List are discarded. This filter may be applied to
all links or selected links.
Unicast Link
Protect Flag
When a frame comes from a link with the Unicast Link Protect Flag set, and if its
source address is not found in the Permanent Station Address list, the frame is
dropped.
When a frame is being sent out over a link with the Unicast Link Protect Flag set,
and if its destination address is not found in the Permanent Station Address List, the
frame is dropped.
Once the Unicast Link Protect Flag is set for a link, source address learning for
Unicast frames is stopped for that link and all the addresses that were learned before
are moved into the Permanent Station Address List.
Setting or Clearing of Unicast Link Protect Flag is performed via the LAN Control
menu located in the Main menu.