Comtech EF Data CDM-570A - Manual (Page 494)

CDM-570L/570AL Satellite Modem with Optional Packet Processor MN-CDM570A
Appendix D Revision 2
D–36
D.3.1.1.2 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, 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 D-5. Managed Switch Mode
Managed Switch Mode is the default working mode for the optional Packet Processor. 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-IP. In this mode, the Packet Processor is acting as a
“smart wire” over a satellite link between two CDM-IPs. This allows the optional Packet
Processor to simultaneously forward IP traffic and non-IP traffic such as IPX.
Figure D-5 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-IP learns which devices are attached
to their local Ethernet interfaces and will only send packets over the satellite that are not
destined for the locally attached devices.