Product specifications

Chapter 1 Introduction
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Chapter 1. Introduction
1.1 Welcome
In telecommunications, TDM over IP (TDMoIP) is the emulation of time-division multiplexing (TDM) over
a packet switched network (PSN). In the case of the IPM-4SE, TDM refers to E1 signals, while the PSN is
based on Ethernet.
TDM over IP is a type of pseudo wire (PW). However, unlike other traffic types that can be carried over
pseudo wires (e.g. ATM, Frame Relay, and Ethernet), TDM is a real-time bit stream, leading to TDM over
IP having unique characteristics. In addition, conventional TDM networks have numerous special features, in
particular those required in order to carry voice-grade telephony channels. These features imply signaling
systems that support a wide range of telephony features, a rich standardization literature, and well-developed
Operations and Management (OAM) mechanisms.
One critical issue in implementing TDM PWs is clock recovery. In native TDM networks the physical layer
carries highly accurate timing information along with the TDM data which is easily recovered using phase-
locked loop (PLL) techniques. However, when emulating TDM over PSNs this synchronization is absent.
TDM timing standards can be exacting, and conformance with these may require innovative mechanisms to
adaptively reproduce the TDM timing.
Another issue that must be addressed is TDM over IP packet loss concealment (PLC). Since TDM data is
delivered at a constant rate over a dedicated channel, the native Ethernet network may have bit errors. All
PSNs suffer to some degree from packet loss, and this must be compensated when delivering TDM over a
PSN.
1.2 Product Description
The IPM-4SE series is a "Multi-service (TDM and Ethernet) Over LAN/MAN" bridge, which transports one,
two, three, or four ports of ITU-T G.703 E1 and one LAN into Ethernet packets. Its target application shown
in Figure 1.2 is the transparent E1 port interconnection via the Ethernet network (using Ethernet packets).
Based upon RFC3916, the IPM-4SE series employs the latest Circuit Emulation System over packet
technology.
The E1 over IP of IPM-4SE is compliant with IETF “CES over IP” standard. Versatile LEDs are provided
for alarms and status indication.
1.3 Features
• Supports E1 (only) over 100M Ethernet to LAN/MAN.
• Provide one LAN for Ethernet access.
• User side provides standard PDH (E1 only) interfaces using balanced signals for twisted pair.
• Full-duplex 100M Ethernet Interface.
• Provides auto-negotiation which can auto configure 10/100M depending on the speed of LAN/MAN port.
• Supports "E1" Timing, i.e. LAN/MAN bandwidth requires at leased 5MHz or 10MHz.
• Provides "ACT" and "ALM" LED indicators for each PDH interface.
• Provides "Link status, Activity" LED indicators for 100M Ethernet interface.
• Stand–alone desktop unit, optional 19" rack mountable.
• Supports AC 100 ~ 240V input and optional DC -36 ~ -75V input for redundancy.
• Important: T1(DS1) is currently not supported in this model.