ZyXEL Communications MSC1024G Series User Manual page 45

Chapter 1 Getting to Know Your MSC
Figure 2 Central Office Application
• Other applications include telemedicine, surveillance systems, remote servers systems,
cellular base stations and high-quality videoconferencing.
IMA Application
Although IP network is common today, there are still some countries using TDM (Time-
Division Multiplex) as their backbone network. TDM is a technology to transmit data, voice
and video signals using different channels and clocks on the same media.
PSTN is also based on TDM technology. E1 and T1 TDM are two well-known connections.
However, those connections are not capable of long distances. In order to increase the
transmission speed and distance, IMA (Inverse Multiplexing for ATM) is a technology that
can group several E1 or T1 lines and be applied to connect remote sites and the central office
(CO) site together through an ATM network (as a backbone).
The IES-5000 and IES-6000 can support the IMA application. With an IMA line card
installed, the IES-5000 and IES-6000 are able to be a bridge between an IP network and an
ATM network.
In the following figure, the remote site's IMA-1 converts Ethernet packets into and from ATM
cells. Through aggregating 5 E1 lines, it can provide an uplink transmission rate of around 10
Mbps. The traffic is transmitted through the closest connected ADM (Add-Drop Multiplexing)
device and then to the TDM network.
After travelling in the TDM network, the traffic is forwarded through another connected ADM
device to the CO site's IMA-2 which converts the ATM cells back into Ethernet packets.
45
MSC1000G/1024G/1224G Series User's Guide