Allied Telesis AT-FS202SC/FS4 - Manual (Page 17)

AT-FS20x and AT-FS202SC/FSx Series Installation Guide
7
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 10/100Base-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 4,000 MAC addresses can be stored in the switch’s MAC address table.
The switch’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 switch will update the table with the new address.
The switch 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filled with addresses of end-nodes that are no longer active.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 switch forwards all multicast, broadcast, and unicast packets when the
MAC address table has exceeded its storage limit.
Store and Forward
The AT-FS20x and AT-FS202SC/FSx Series Switches 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 switch 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 switch,
reducing network load. For example, if the packet entering from Port 1 is
destined for an end-node on Port 2, the switch 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.
The switch will discard CRC errors, misaligned, runt, and under-oversized
packets. When the packet has dribble bits at the end, the switch will truncate
to octet boundary and check for a good FCS before forwarding.