Allied Telesis AT-CM70S - Manual (Page 23)

Converteon Media Converter Line Cards Reference Guide
23
Note
Restriction of Operation: While operating two AT-CV102 line cards
back-to-back, where both cards are in SML mode, if the fiber
connection between them is broken, remove the copper connection
to one of the AT-CV102 cards before restoring the fiber link between
them. Then wait at least 20 seconds before restoring the copper
connection.