Hitachi GR2000 - Manual (Page 255)

When you connect GR2000 and any other router on Ethernet, pay attention to th
restrictions shown below.
4.4.1 10BASE-T/100BASE-TX
Match the interface type (10BASE-T or 100BASE-TX) and the full-duplex/
half-duplex mode setting between GR2000’s configuration definition and the oth
router’s interface status. Otherwise, connection will fail.
4.4.2 100BASE-FX
GR2000 can be defined to operate either in full-duplex fixed mode or in half-dup
fixed mode on 100BASE-FX. Set up the configuration information in accordance w
the line speed of the neighbor connection device (e.g., media converter).
4.4.3 1000BASE-SX/1000BASE-LX/1000BASE-LH
GR2000 can operate only in full-duplex fixed mode on 1000BASE-SX,