Link fault signaling

The SLX platform supports Link Fault Signaling (LFS) detection for interface types of 10G, 40G, 100G, and 40G breakout ports. It detects local and remote faults.

Note

LFS is not supported in 1G mode.

When the device detects a local fault, it returns a remote fault to the link partner. When the device detects a remote fault, it returns an idle state.

A port's physical link detection is independent of LFS detection. When either of these link fault signals is detected, the following behaviors occur:

The link is declared as DOWN and the port should display Protocol Down on the SLX-OS CLI.
The physical link is not bought down in both of the previous cases. The peer side based on its implementation might display that the link is UP when the Extreme device displays that the link is DOWN due to a fault detection.
The transmit (TX) packets, if any, are dropped at the MAC layer. The receive (RX) packets, if any, are dropped in the software.
The detected signal is reported as a RASTRACE message on the line card. The same information is reported on the MM as a RASLOG. The same behavior occurs when the signal is cleared.

You can enable or disable LFS globally and on the interface level for both RX and TX directions:

If the LFS is enabled for RX, the normal local and remote fault detection and processing described previously occur. If it is disabled for RX, local and remote fault detection are ignored.
If the LFS is enabled for TX and a local fault occurs, a remote fault (pause frame) is generated to the remote side. If it is disabled for TX, the remote fault is not generated.