Quantum and Evolution Series Installation and Operating Handbook
8-39
over the ESC on port 6703 are forwarded out of the serial RS485 M&C
interface (i.e. converted from IP to serial commands).
o
Packets sent to port 6704 are forwarded over the ESC to port 6701 on the
remote modem. At the remote modem, packets received over the ESC on
port 6701 are treated as local M&C commands for the modem and go no
further.
•
You can send M&C packets to port 6701 on the local modem at any time when
using the ESC channel in IP mode, without having to set the ‘
Remote M&C
interface
’. If you just want to bridge IP packets then you can ignore the remote
M&C interface setting.
To summarise the ESC bridging options:
•
IP can be used over the ESC and the main data channel at the same time, whether
using the base modem IP or the IP Traffic card.
•
With the M&C port in the bridge and IP selected for both the ESC and main data
channel, the M&C port is now bridged to the ESC channel
not the IP traffic port.
The IP traffic port is still bridged, but only to the satellite port (when the ESC is not
being used, bridging the M&C port bridges it to the IP traffic port and the satellite
port)
Note that the ESC channel is used to support the AUPC feature but this does not prevent it
being used for other purposes at the same time (the AUPC messages are just multiplexed
in with the other data).
8.12.6 IP Interoperability
Over satellite, the modem uses HDLC to encapsulate the Ethernet frames or IP packets
(unless DVB-S2 is being used, in which case another form of encapsulation is used such
as MPE or ULE). If Cisco HDLC is selected on the modem then the received IP stream can
be forwarded out of a serial interface to a serial router that supports Cisco HDLC, which
can convert it back to IP.
In general different modem manufacturer’s IP, even when using HDLC, is not interoperable
as there is no standard defined in this area. If instead DVB-S2 is used, then generally IP is
interoperable between different manufacturer’s modems, so long as incompatible IP
features are not being used such as compression or acceleration.
8.12.7 IP Connectivity Modes
The modem software supports several types of Ethernet network topology.
Firstly, there is a point-to-point mode for when one modem is transmitting to and receiving
from one other modem (i.e. there is a direct satellite return path).
Secondly, there is a point-to-multipoint mode for when one hub modem is transmitting to
several remote modems. The remote modems may be Rx only or may transmit back to Rx-
only modems at the hub that are daisy-chained together to the hub Tx modem (to allow all of
the hub modems to share the hub Tx carrier).
