Comtech EF Data CDM-760 User Manual
Page 113
Front Panel Operation
Revision 2
CDM-760 Advanced High-Speed Trunking Modem
MN-CDM760
6–27
6.2.2.4.1 Single Stream Mode or MultiStream Mode Operation
Single Stream Mode is the conventional method for transporting a single type of traffic data
over the satellite. MultiStream Mode allows more than one type of traffic data to be active at
the same time.
For Single Stream Mode:
•
A single PIIC module is installed and active, and all other interfaces are either NONE (not
installed) or OFF (installed, but not active), OR:
•
Any combination of Gigabit Ethernet is enabled, but all PIIC slots are either NONE (not
installed) or OFF (installed, but not active);
Gigabit Ethernet combination examples are:
o
GBEI1 / J5 | DATA port
o
GBEI2 / J6 | DATA port
o
Optical / J7 |OPTICAL port
The modem treats the three Gigabit Ethernet data interfaces as a single data
interface type, no matter how many are active.
For MultiStream Mode:
•
MultiStream Mode is an internal multiplexing (MUX) and de-multiplexing (De-MUX) of data
interface types. This allows two or more data traffic types to simultaneously coexist in a
single carrier.
•
One or more of the GbE interfaces MUST be active in order to ENTER or exit from
MultiStream Mode. Therefore, at least one of the GbE interfaces must be active at the same
time that at least one of the PIIC slots is active (e.g., PIIC1=G703-E3). The CONFIG: Intf
screen display example shows the modem in MultiStream Mode.
•
Adaptive Coding and Modulation (ACM) is not functional in MultiStream Mode. All other
WAN optimization features are functional in MultiStream Mode.
•
Because MultiStream Mode is a MUX of different data types, there is overhead associated
with the total MUX structure. This associated overhead is 1.5% of the aggregate non-
Ethernet data in Normal Block Mode, and 5% in Short Block Mode.
For example: You are running a link in Normal Block Mode that is using MultiStream to
aggregate Ethernet traffic and two G.703 E3 (34.368 Mbps) connections.
The computation of the modem Tx link’s configuration for minimal support is therefore:
(34.368 + 34.368)* 1.015 = 69.768 Mpbs
Any data rate that is ABOVE this minimum data rate is given to the GbE interfaces.