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3. Functions
To help a better understanding about the software management interfaces, this chapter describes some
advanced functions provided by the media converter.
3.1 Abbreviation
TP Port : The twisted-pair copper port of the media converter device.
FX Port : The optical fiber port of the media converter device.
Ingress Port : Ingress port is the input port on which a packet is received.
Egress Port : Egress port is the output port from which a packet is sent out.
IEEE 802.1Q Packets : A packet which is embedded with a VLAN Tag field
VLAN Tag : In IEEE 802.1Q packet format, 4-byte tag field is inserted in the original Ethernet frame
between the Source Address and Type/Length fields. The tag is composed of :
#of bits
16
Frame field
TPID
TPID : 16-bit field is set to 0x8100 to identify a frame as an IEEE 802.1Q tagged packet
User Priority : 3-bit field refer to the 802.1p priority
CFI : The Canonical Format Indicator for the MAC address is a 1 bit field.
VID : VLAN identifier, 12-bit field identifies the VLAN to which the frame belongs to.
Untagged packet : A standard Ethernet frame with no VLAN Tag field
Priority-tagged packet : An IEEE 802.1Q packet which VID field value is zero (VID=0)
In the device, this packet is also treated as untagged packet.
VLAN-Tagged packet : An IEEE 802.1Q packet which VID field value is not zero (VID<>0)
PVID (Port VID)
PVID is the default VID of an ingress port. It is used in 802.1Q filtering for untagged packets. It is also
often used as [Default Tag - VID] for egress tagging operation.
DSCP : Differentiated Service Code Point, 6-bit value field in an IP packet
3.2 Converter Function
The device supports the following data conversions between fiber cable and twisted-pair Cat.5 (cop-
per) cable:
The data rate on twisted-pair segment depends on the link speed finally established with the link part-
ner.
3
1
12
User priority
CFI VID
-20-
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