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
3
1 12
Frame
field
TPID
User
priority CFI
VID
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.
3.2 Converter Function
The device supports the following data conversions between fiber cable and twisted-pair Cat.5 (copper) cable:
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