RAD Data comm RIC-E1 Backpressure and Flow Control, Table C-4. IR-ETH/V LED Indicators

Appendix C IR-ETH/V Interface Module RIC-E1Installation and Operation Manual

Backpressure and Flow Control

DIP switch SW1/4 enables or disables both backpressure and flow control.

When the IR-ETH/V is set to half duplex, backpressure is active, and when the IR- ETH/V is set to full duplex, flow control is active.

Note Full duplex flow control activation requires autonegotiation to be enabled.

Backpressure is the term given when the buffer is filled from the LAN faster than it is able to transmit to the WAN. In order to prevent packet loss, collisions are forced into the LAN, which causes the link partners to go into backoff before attempting to retransmit. Reducing, in effect, the traffic coming through the interface.

Flow control is active only in full duplex mode. When the buffer is filled from the LAN faster than it is able to transmit to the WAN, pause frames are sent to the LAN, ordering the LAN to stop for a time interval indicated by the pause frame until transmission starts again.

Note To use the flow control option, the link partners (switches etc.) should support flow control.

LED Indicators

Table C-4lists the IR-ETH/V LED indicators and describes their functions.

		Table C-4. IR-ETH/V LED Indicators
LED	Color	Function
LINK	Green	ON – LAN is connected
ACT	Yellow	Blinks – Transmit/receive activity is detected on the Ethernet link
100M	Green	ON – LAN is operating at 100 Mbps

Connecting the LAN

Use either a straight cable or a cross cable for the LAN connection.

Use a cross cable when connecting to a port that does not implement the crossover function internally. Otherwise, use a straight cable.

Note Hubs usually implement the crossover function internally, while NICs and other devices do not.

C-6 Installation and Operation

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