21 — Transparent rate adaption
21-2
2902 MainStreet Technical Practices
90-2906-01 May
2002
21.1
Rate adaption overview
Rate adaption techniques allow subrate data devices to use a 64 kb/s channel by
formatting the data to conform to the primary rate framing structure. Using rate
adaption, several subrate data devices can be multiplexed onto one primary rate
channel.
Setting rate adaption parameters defines data transport information, such as
bandwidth allocation and data position within the channel. Data from each circuit
must be positioned so that it does not overlap data from other circuits.
21.2
Transparent rate adaption overview
Transparent rate adaption provides a transparent channel (carrying data, signaling
and framing information from a data device) through the node without adding any
signaling or framing information.
Transparent rate adaption divides a 64 kb/s channel into eight elements; each element
is transmitted 8000 times per second. Each element represents 1 bit and, therefore,
8000 b/s of bandwidth.
Transparent rate adaption supports synchronous data running at a rate that is a
multiple of 8 kb/s. If a device is transmitting asynchronous data, transparent rate
adaption cannot be used.
After transparent rate adaption is selected, two parameters can be set:
•
transport bandwidth
•
transport position
Figure 21-1 shows how a transparent channel is represented on an NMTI display,
where each D represents 8 kb/s of bandwidth and B7 to B0 represent starting
positions within the channel. Elements that do not contain a D represent unused
bandwidth. Figure 21-1 shows a 32 kb/s transparent channel with starting position
B7. The right side of the display shows all current circuit parameters, including the
transport bandwidth (beside the Rate adaption heading) and the transport position.
Note 1 —
A module position must be configured before its circuits
can be configured with rate adaption parameters.
Note 2 —
Circuits configured as master or slave in a multidrop
configuration are an exception in that they must be positioned to
overlap. However, multidrop circuits should not overlap circuits that
are not part of the multidrop data bridge.
Summary of Contents for MainStreet 2902
Page 1: ...2902 MainStreet Network Termination Unit Release 1 0 H T E C H N I C A L P R A C T I C E S ...
Page 40: ...3 Mounting the unit 3 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 50: ...4 Ground and power connections 4 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 68: ...6 Connecting to the network 6 4 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 90: ...7 Connecting to data devices 7 22 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 108: ...10 Node management 10 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 150: ...14 CPSS 14 6 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 218: ...20 Codirectional DCM 20 6 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 234: ...22 HCM rate adaption 22 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 246: ...23 Cross connecting circuits 23 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 254: ...24 Visual indicators 24 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 266: ...25 Alarms 25 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 278: ...26 System diagnostics 26 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 298: ...27 Loopbacks 27 20 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 332: ...Glossary GL 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
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Page 344: ... 2002 Alcatel All rights reserved 90 2906 01 95 1820 01 00 C ...