Q-Lite Satellite Modem Installation and Operating Handbook
7-18
7.8.2 IP Addressing
The Ethernet ports on the 4-port Gigabit Ethernet switch are always bridged together. This
is true regardless of what bridging or routing mode is selected. In bridging mode, IP
addresses are not used so there is no restriction on what subnets are connected to the
switch traffic ports. In routing mode, since the Ethernet switch card has a single address
covering all ports, only one direct subnet can be connected to the ports.
When the M&C port is not bridged to the traffic port(s) then it has its own IP address. In this
case the IP traffic port and M&C port
must
be on different subnets because otherwise the
modem does not know which port to respond out of.
7.8.2.1 Gateways
There is a single gateway address for the modem. This can be applied to any subnet. If
further gateways are required then these can be applied as static routes.
7.8.3 Throughput Performance
Actual throughput performance depends on a number of factors including one way/two way
traffic, packet size, data rates and the mixture of IP features switched on. There are
endless combinations and therefore it is strongly recommended that empirical testing is
undertaken prior to deployment to ensure that the required level of service can be provided.
The modem can process up to 150,000 packets per second. (In Trunking mode this
increases to 500,000 packets to second.) It is good practice to put a switch (or router)
between the modem and local network in order to minimize the number of packets the
modem has to process, as incidental network traffic (not intended for satellite) has the
potential to push the modem over it packet processing limit.
TCP acceleration works to at least 100Mbps.
Header compression works to 60,000 packets per second one way, 45,000 two way.
7.8.4 Jumbo Ethernet Frame Support
The modem supports Ethernet frames up to 10k bytes in length. For optical Ethernet, this is
increased to 16k bytes.
7.8.5 M&C VLAN
Traditionally, the Engineering Service Channel (ESC) was used as a separate channel to
the main data channel. The ESC was used for control of remote equipment (modem, BUC,
etc.).
Modern satellite services such as DVB-S2 and DVB-S2X do not incorporate an ESC
channel. Paradise has chosen to create an alternative, which is a special VLAN that is
used just for M&C traffic. VLAN 0 is used for this purpose and should not interfere with user
VLAN traffic. Simply by turning on the M&C VLAN option in both modems in a point-to-point
link, the modem will ensure that M&C traffic is kept separate from user traffic and it will