Frame Switching - Phoenix Contact FL SWITCH SMN 6TX/2POF-PN User Manual

Smart Managed Compact Switch
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PHOENIX CONTACT
3.3

Frame switching

The FL SWITCH SMN operates in store-and-forward mode. When receiving a data packet,
the switch analyzes the source and destination addresses. The switch stores up to 4000
MAC addresses in its address table with an adjustable aging time of 10 to 825 seconds.
3.3.1 Store and forward
All data telegrams received by the switch are stored and checked for validity. Invalid or
faulty data packets (>1522 bytes or CRC errors) and fragments (<64 bytes) are rejected.
Valid data telegrams are forwarded by the switch.
3.3.2 Multi-address function
The switch learns all the source addresses for each port. Only packets with:
– Unknown source addresses
– A source address for this port or
– A multicast/broadcast address
in the destination address field are forwarded via the relevant port. The switch can learn up
to 4000 addresses. This is important if more than one termination device is connected to
one or more ports. Several independent subnetworks can be connected to one switch.
3.3.3 Learning addresses
The FL SWITCH SMN independently learns the addresses for termination devices, which
are connected via this port, by evaluating the source addresses in the data telegrams. When
the FL SWITCH SMN receives a data telegram, it forwards this data telegram to only that
port that connects to the specified device (if the address could be learned beforehand).
The FL SWITCH SMN can learn up to 4000 addresses and store them in its table. The
switch monitors the age of the learned addresses. The switch automatically deletes from its
address table address entries that exceed a specific age (default: 40 seconds, adjustable
from 10 to 825 seconds, aging time).
All learned entries are deleted on a restart.
A link down deletes all the entries of the affected port.
A list of detected MAC addresses can be found in the MAC address table (see Section
""Diagnostics, Mac Address Table" menu" on page 46). The MAC address table can be
deleted via the "Clear" button.
The aging time is set using the "dot1dTpAgingTime" MIB object (OID 1.3.6.1.2.1.17.4.2).
The available setting range is 10 to 825 seconds. For static configuration, an aging time
of 300 seconds is recommended.
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