Comtech EF Data CDM-570 - Manual (Page 441)

CDM-570/570L Satellite Modem with Optional IP Module Revision 12
Appendix G MN/CDM570L.IOM
G–5
G.3.3 Managed Switch Mode
Managed Switch Mode will automatically use Layer 2 Header Compression,
even if the Header Compression option has not been purchased. Because of
this, some of the initial traffic sent between two devices will not be received
over the satellite until a full header is transmitted.
For example, the default Header Compression Refresh Rate is 50 packets. If a
ping is sent over the satellite, then it will time out until the full Header packet is
sent.
The Header Compression Refresh Rate on the Administration Menu can be
reduced to minimize the amount of traffic lost when traffic is first sent between
two devices. Once communication between two devices has been established,
both modems will be able to receive all traffic, unless one modem is power-
cycled or reset.
Figure G-1. Managed Switch Mode
Managed Switch Mode is the default working mode for the optional IP Module. This mode
allows the modem to be set up with minimal configuration (no specific routes need to be
configured). Managed Switch only operates in Point-to-Point Mode, meaning that it is
communicating with only one other CDM-570/L-IP. In this mode, the IP Module is acting as a
“smart wire” over a satellite link between two CDM-570/L-IPs. This allows the optional IP
Module to simultaneously forward IP traffic and non-IP traffic such as IPX.
Figure G-1 shows a 256 kbps Point-to-Point duplex link in Managed Switch Mode. Note that
both sides of the link are on the same IP subnet – 10.10.0.0/16. There are no routes or HDLC
addresses to configure. When the system is powered-up, all packets from each subnet (local and
remote) will be sent over the satellite interface. Each CDM-570/L-IP learns which devices are