Many media converters include a set of DIP switches on the back or underside of the device, allowing users to enable or disable specific features like flow control, jumbo frames, or link fault pass-through. These settings can make a big difference in performance and compatibility — especially when switching between 1.25Gbps (Gigabit Ethernet) and 100Mbps (Fast Ethernet) modes.
This guide explains what each DIP switch setting typically controls and how to use them correctly depending on the speed you're operating at.
These settings apply when the media converter is operating at 1.25Gbps — typically when both ends of the link support Gigabit Ethernet.
JUMBO (Default: OFF)
Enables jumbo frame support, increasing the maximum Ethernet frame size from the standard 1,500 bytes to around 9,000 bytes. Jumbo frames can improve network performance in environments with large file transfers or video streams — but only if all devices in the data path also support them.
LFP – Link Fault Pass-Through (Default: OFF)
When enabled, the media converter will report a link failure on one side (e.g., fiber or copper) if the opposite side loses connection. This is useful for making faults visible to upstream switches or devices, simplifying troubleshooting.
FDX – Full Duplex (Default: ON)
Enables full-duplex operation, allowing simultaneous sending and receiving of data. This should usually remain ON for Gigabit Ethernet networks, which are designed for full-duplex.
FLOW – Flow Control (Default: OFF)
Activates IEEE 802.3x flow control, which lets devices pause transmission temporarily to prevent packet loss during congestion. Whether to enable this depends on your network setup — it can help in some environments but may introduce latency in others.
These switches only apply if the media converter is operating at 100Mbps, such as when connecting to a Fast Ethernet device on one end.
RESET (Default: OFF)
Acts as a manual reset switch for the media converter. Toggling it ON (usually momentarily) will reboot the device without removing power.
HALF (Default: OFF)
Forces half-duplex mode, which allows data to flow in only one direction at a time. This is mostly used for compatibility with very old networking equipment that doesn’t support full-duplex.
LFP – Link Fault Pass-Through (Default: ON)
Similar to the 1.25G LFP switch, this setting makes sure that a disconnection or fault on one side of the converter will also bring down the link on the other side. Enabled by default in 100M mode for better visibility of faults.
10M (Default: OFF)
Forces the media converter to operate at 10Mbps instead of 100Mbps. Only enable this when connecting to older legacy devices that require 10BASE-T speeds.
The 1.25G vs. 100M switch groups are independent — only the group relevant to your current link speed will apply.
Always power cycle or use the RESET switch after changing DIP settings to ensure they take effect.
Use LFP to make sure link failures don’t go unnoticed upstream.
Only enable jumbo frames or flow control if your network specifically benefits from them.
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