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24-port NWay Ethernet Switch User’s Guide
Switch Management Concepts
31
Filtering Database
A switch uses a filtering database to segment the
network and control communications between segments.
It also filters packets off the network for intrusion
control (MAC Address filtering).
For port filtering, each port on the switch is a unique
collision domain and the switch filters (discards)
packets whose destination lies on the same port as
where it originated. This keeps local packets from
disrupting communications on other parts of the
network.
For intrusion control, whenever a switch encounters a
packet originating from or destined to a MAC address
defined by the user, the switch will discard the packet.
Filtering includes:
1.
Dynamic filtering – automatic learning and aging of
MAC addresses and their location on the network.
Filtering occurs to keep local traffic confined to its
segment.
2.
MAC address filtering – the manual entry of specific
MAC addresses to be filtered from the network.
3.
Filtering done by the Spanning Tree Protocol, which
can filter packets based on topology, making sure
that signal loops don’t occur.
4.
Filtering done for VLAN integrity. Packets from a
member of a VLAN (VLAN 2, for example) destined for
a device on another VLAN (VLAN 3) will be filtered.