Quick Eagle Networks DL3800E - Manual (Page 30)

2-4 DL3800E Inverse Multiplexer User’s Guide — July 9, 2001
2
F
UNCTIONAL
D
ESCRIPTION
The base DL3800E unit configuration consists of a motherboard with two
(E1) network interface connectors and the DTE connectors (HSSI and
V.35/RS449/X.21). Six additional E1 network ports can be added with the
addition of from one to three daughterboards, each daughterboard
supporting two additional E1 ports.
The general operation of the DL3800E unit is explained in the following
paragraphs which describe the signal flow and overhead functions.
Signal Flow
The DL3800E unit is configured by you for the number of E1 signals to be
used for transmission. The DL3800E unit will provide a smooth clock to the
DTE at the data rate required for the number of E1 outputs you have
configured. For E1, this rate will be Nx1.976 Mbps, where N is the number
(1 to 8) of E1s to be used.
The transmit smooth clock PLL can use any of the incoming E1 clocks, an
external clock, or internal clock as reference. The receive smooth clock will
use one of the receive clocks at its source. The smooth clock VCO will be
divided down to 8 kHz to be phase compared to the 8 kHz reference. The
receive buffers are large enough to accommodate variations between E1
receive clocks.
The DL3800E unit supports one DTE interface. For data rates up to 6 Mbps,
the DTE interface can be HSSI or V.35/RS449/X.21 (software selectable).
For data rates over 6 Mbps, only the HSSI interface will be supported.
Data is sent from the DTE interface to an Inverse Multiplexer (IMUX)
transmit framer. A 16-bit proprietary framing pattern is defined to satisfy
the requirements of inverse multiplexing communications. This frame is
constructed by using one payload bit in each frame for 16 consecutive
frames. For E1, the inverse multiplexing frame is the first bit after the
framing bit.
From the inverse mux framer, the data is sent to all E1 framers, where the
E1 framing is added, and then to the appropriate E1 network interface and
out over the E1 network.
All incoming configured E1 lines, with their respective clocks, are received
into a standard E1 framer. The output of the E1 framer is fed into the IMUX
framer.
Data coming into the DL3800E Inverse Multiplexer is stored in N
independent buffers, where N is the number of configured input channels.
From these buffers, the data will be read and IMUX framing removed.