MN-DMD20-20LBST Revision 14
J–1
Appendix J. Ethernet Data
Interface Setup
J.1
Configure the modem to use the Ethernet Data Interface (Optional)
When the optional 10/100 or 10/100/1000 Base-T Ethernet Data Interface Card is installed, all of
the Ethernet related menus become available and can be used to control the interface as follows:
Under the Interface Menu:
Under the Tx Setup Menu:
Set the Terrestrial Interface to Ethernet.
Set the Ethernet Flow Control as desired (refer to Section 4.8.1 for details).
Set the Ethernet Daisy Chain as desired (refer to Section 4.8.2 for details).
Set the Ethernet QOS Type as desired (refer to Section 4.8.3 for details).
Set the Ethernet QOS Queue as desired (refer to Section 4.8.4 for details).
Set the Tx Clock to SCTE.
Set the Tx Clock Polarity to Normal.
Under the Interface Menu:
Under the Rx Setup Menu:
Set the Terrestrial Interface to Ethernet.
Set the Buffer Size to Zero.
Set the Buffer Clock to Rx Sat.
Set the Buffer Clock Polarity to Normal.
When Ethernet Data Interface is selected, the Tx Clock Source will default to SCTE and the Clock
Polarity will default to Normal. In addition, the Buffer Clock will default to RxSat and the Buffer
Clock Polarity will default to Normal.
The DMD20 supports Radyne HDLC and Comtech HDLC modes, offering
compatibility with the SLM5650A Bridge Interface.
J.1.1 Ethernet Flow Control
When disabled, if a packet is received for transmission and no packet buffer space is available,
the incoming packet is discarded.
When enabled, flow control is used to throttle the transmission station in order to avoid
overrunning the transmit buffers, which would in turn cause packets to be dropped. The throttling
mechanism used depends upon the interface and whether it is half-duplex or full duplex.
IMPORTANT