Omicron EMCON 200, User Manual, Page: 11 / 19

8 Conversion modes
EMCON 200 is a media converter with cut-through forwarding and offers the following two conversion
modes: PTP mode and direct mode.
8.1 PTP mode
EMCON 200 works as a PTP transparent clock that preserves PTP time synchronization. It modifies
PTP messages as they pass through the media converter. EMCON 200 knows how long a packet
needs to pass through, i.e., it knows the packet's residence time. EMCON 200 writes this residence
time into the correction field of all PTP event packets.
8.2 Direct mode
When using direct mode, data is converted directly on the physical layer without adding or removing
any information. In this mode,
EMCON 200 has minimum packet delays, but the delays are different
for the two directions (i.e., "fiber to copper" and "copper to fiber"). The asymmetry of the packet delays
affects the PTP path delay measurements, and this influences the PTP time synchronization accuracy
in the network.
In special cases where two EMCON 200 media converters are used “back to back”, the asymmetry of
the direct mode is compensated. Two common examples are shown in subsections Network TAP and
Long distance fiber connections .
8.2.1 Network TAP
When you set up a network TAP to monitor or record network traffic, use two EMCON 200 media
converters to connect your tapping device (e.g., OMICRON's DANEO 400 device) to the optical fiber
network. The packet asymmetry created by the first media converter ("fiber to copper" connection) is
compensated by the second media converter ("copper to fiber" connection).
EMCON 200
EMCON 200
DANEO 400
(in TAP mode)
Twisted pair Ethernet cables
Optical fiber cables
Conversion modes
OMICRON 11