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3.1.3.
Frame-Switching
The switch operates in store-and-forward mode. If a data packet is received, the switch
analyzes the source and destination address. The switch is able to store up to 1024 MAC
addresses in its address table, with a retention time of 48 seconds.
•
Switching Fabric Unit (SFU):
The SFU receives the error-free packets from the
ports for processing and forwarding to the MAC address of the destination device.
The SFU has the ability to learn which packages must be forwarded to the ports.
This sets the SFU on a table with the source addresses of the packets and the
number of ports on which the packets are received. Using the generated table and
the destination MAC addresses, the SFU can decide which packages must be sent
via which port.
•
Address Lookup-Table (LUT):
The LUT is generated by the internal lookup engine.
It stores all the source addresses of incoming packets, together with the port
number of the switch. Up to 4096 number address port mappings may be stored in
the address table. This procedure is necessary, if a plurality of terminals is
connected to a port or plurality of ports. In this case, different and independent sub
networks are connected via the switch.
•
Find addresses:
Initial for incoming packets: At first it will be searched in the
lookup table for the destination address. If the destination address is provided, the
number of the output ports to the output port queue manager is forwarded. After
that the packet is forwarded to the appropriate output port. Packets with a
multicast or broadcast address will be forwarded to all output ports, but to the
input port.
•
Learning addresses:
If the MAC address of the target device is not in the lookup
table, the switch switches to the self-learning mode. The switch sends the packet to
all ports in order to enable the forwarding of the packet to the correct destination
device. A device responding to this packet will learn its MAC address of the SFU. The
new MAC address and port are stored as an entry in the lookup table. All future
packets are transmitted directly and exclusively through this port to the destination
station.
•
Provision of addresses:
the process of provision of addresses is running
continuously. Each access to the lookup table is counting up the aging time of the
entries. If an entry is too old because the connection is terminated at a network
node or the device is disabled, it will be removed from the address table. The
maximum aging or derivative time is 300 s.
3.2.
Advanced Functionality
In addition to the basic protocol settings of the switch has the following extended
functionality.
