Allied Telesis AT-FS238a/2 - Manual (Page 23)

AT-FS238a/x and AT-FS238b/x Series Installation Guide
11
DIP Switches
The DIP switches are used to manually configure the operating characteristics
of the ports. These characteristics include the port speed, duplex mode, and
auto-negotiation.
On the 100Base-FX fiber optic port, you can manually set the duplex mode to
either half- or full-duplex.
On the 10Base-T/100Base-TX twisted pair port, you can manually set the
speed of the port to either 10 Mbps or 100 Mbps, set the duplex mode to either
half- or full-duplex and enable or disable auto-negotiation. Enabling auto-
negotiation will automatically set the port’s speed and duplex mode.
MAC Address Table
Up to 2,000 MAC addresses can be stored in the bridging converter’s MAC
address table. The bridging converter’s self-learning feature will learn all new
addresses in real-time after power-up. If the source address of an incoming
packet is not found in the MAC address table, the bridging converter will
update the table with the new address.
The bridging converter also has an automatic address aging feature that will
delete a source address from the table if it has not seen a frame from the end-
node with that address within five minutes. This prevents the table from
becoming filled with addresses of end-nodes that are no longer active.
The bridging converter forwards all multicast, broadcast, and unicast packets
when the MAC address table has exceeded its storage limit.
Store and Forward
The AT-FS238a/x and AT-FS238b/x Series Bridging Converters support store
and forward switching at Fast Ethernet full-wire speed in 100 Mbps, half- or
full-duplex mode. Packets entering each port are stored in buffers. Once the
full packet is received, the bridging converter will forward or discard the
packet, depending on its destination address and error status. This ensures
that only error-free packets destined for another segment will be transferred
across the bridging converter, reducing network load. For example, if the
packet entering from Port 1 is destined for an end-node on Port 2, the bridging
converter forwards the frame if the frame does not contain any errors. If the
packet from Port 1 is destined for an end-node also connected to Port 1, the
packet is discarded.