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Network Termination Controller NTC
The NTC is a full-duplex network terminator which is designed to implement Transmit
Convergence (TC) sub-layer functions for physical media based on SDH/SONET, SDH,
DS3 and E3. The device includes a generic 8-bit parallel interface to an external
transceiver which is only required to provide serial/parallel conversion and the clock
- Implements framed and cell based physical layer OAM (PL-OAM) functions or FI, F2 and F3 flows
- Supports F4/F5 OAM cell insertion /extraction
- Maintenance of statistics for all active per virtual circuits, including cell and error
and OAM statistics
- On-chip DMA controller for high-speed transfer of statistics and
inserted/extracted cells to/from system memory
- Interfaces directly to MB86689 Address Translation Controller to perform real-time cell header translation
- JTAG compliant
The NTC is ideally suited to applications in ATM adapter cards and hubs. It can be used
for UNI or NNI applications and conforms to the relevant specifications. Two possible
configurations involving the NTC are shown.
In the ATM terminal equipment, the NTC is connected to the Adaptation Layer Controller
(ALC). It takes the ATM cells generated by the ALC and performs all the framing
functions required by the selected physical media. An external transceiver handles
media-dependent functions such as line coding, clock recovery etc. The NTC also
scrambles the payload data using one of two polynominals. If no user cells are available,
the NTC will generate idle cells to maintain a constant cell stream on the network. Other
cell types such as signalling cells can be inserted into the cell flow using the on-chip DMA
In the receive direction, the NTC synchronizes to the framed data and to the ATM cells.
Statistics information is extracted from the framing bytes and the payload data
unscrambled. The statistics collected are stored on a per virtual-circuit basis, either
on-chip or local memory. The NTC contains a cell buffer which effectively de-couples
network and system clocks. Cells are temporarily stored here while optional address
translation on the VPI/VCI fields of received cell headers is performed by the ATC.
Alternatively, the ALC handles partial address translation based on the sub-set of VP and
VC bits. The relevant header fields are passed across a local interface on a per-byte basis.
Once the ATC has completed any translation the new header value is returned to the
NTC, appended to the cell information field, and the cell output to the ALC across the
asynchronous cell stream interface.
The part is packaged in 176 pin PQFP.
Technology: || unknown|
Package: ||PQFP 176 Pin|
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