EXFO FTB-8500 Series for FTB-500 - Manual (Page 156)

Port Tabs
142 FTB-8500 Series and FTB-8120NGE/8130NGE
Interface Setup (Ethernet)

Flow Control
Available with Frame Analyzer (FTB-8510B and FTB-8510G), RFC
2544, and TCP Throughput stest only. Flow control is not supported
(set to None) for EtherSAM, BERT and Smart Loopback tests. When
Flow Control is enabled, the Ethernet and Fibre Channel Application
will stop transmitting for the requested time value specified by the valid
flow control frame received. Choices are None, Enable RX, Enable
TX, and Enable RX and TX. Only None and Enable RX are available on
FTB-8510G. Enable TX and Enable RX are only available when
Auto-Negotiation is disabled.
None (FTB-8510B/FTB-8120NGE/FTB-8130NGE/FTB-8525/FTB-8535):
pause frame received are ignored and no pause frame are transmitted.
Note: Flow Control should be set to None with Half Duplex mode.

Local Clock Only available for 1Gbps electrical when auto-negotiation
is disabled. Choices are Local, Remote, and Automatic. The default
setting is Automatic.