Phoenix Contact 1708 M12 POE, User Manual, Page: 22 / 34

FL SWITCH 1708 M12 POE
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PHOENIX CONTACT 105648_en_01
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.
3.4.3 Learning addresses
The switch independently learns the addresses for termination devices, which are con-
nected via this port, by evaluating the source addresses in the data telegrams. When the
switch 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 switch 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 address entries from its
address table that have exceeded a specific age (default: 40 second aging time).
3.4.4 Prioritization
The switch supports four priority queues for adjusting the internal packet processing se-
quence (traffic classes according to IEEE 802.1D). Data telegrams that are received are as-
signed to these classes according to their priority, which is specified in the VLAN/prioritiza-
tion tag:
– Data packets with the value “0” or “1” in the priority field are transmitted with the lowest
priority (default).
– Data packets with the value “2” or “3” in the priority field are transmitted with the second
lowest priority.
– Data packets with values between “4” and “5” in the priority field are transmitted with the
second highest priority by the switch.
– Data packets with values between “6” and “7” in the priority field are transmitted with the
highest priority by the switch.
Processing rules
The switch controller in the device forwards received packets to the available receive
queues according to the following decisions:
– Packets with VLAN/prioritization tag are forwarded according to the queues listed
above.
– All remaining data is assigned to the low-priority queue.
3.4.4.1 Class of Service - CoS
Class of Service refers to a mechanism used to take into consideration the value of the pri-
ority field (values 1 to 7) in VLAN data packets with a tag. The switch assigns the data
streams in various processing queues, depending on the priority information contained in
the CoS tag. The switch supports four internal processing queues.
All learned entries are deleted on a restart.
A link down deletes all the entries of the affected port.