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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—HSS Coprocessor
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
736
Reference Number: 004US
13.5
HSS Supported Framing Protocols
The following sections provide an overview of some Framing Protocols supported by
each of the HSS interfaces for the IXP45X/IXP46X network processors, in addition to
the recommended HSS interface setting for each protocol that are configured using the
IxHssAcc API defined in the Intel
®
IXP400 Software Programmer’s Guide.
13.5.1
T1
T1 is a serial data stream operating at 1.544 MHz. The stream is composed of frames of
which there are 8000 a second. Each frame consists of 1 frame bit and 24 time slots,
each time slot is a byte in size. As there are 24 time slots per frame, T1 can carry 24
channels.
illustrate a typical transmitted T1 frame with an active high
frame sync (level) and a positive edge clock for generating data. The HSS clock and
frame pulse can be programmed to be either HSS outputs or HSS inputs.
shows an example with an internally generated frame pulse.
example with an externally generated frame pulse. An offset can be can programmed
indicating when the TX frame is to be transmitted. The Polarity of the received data and
the level of the frame can also be programmed using the IxHssAcc API.
2.048 MHz
-8.204
15
118.957
4.096 MHz
10.9
15
190.742
8.192 MHz
12.951
15
226.634
Table 241.
HSS Frame Output Characterization
HSS Tx/Rx Frequency
Frame Size (Bits)
Actual Frame Length (µS)
Frame Length Error (PPM)
512 KHz
32
62.496249
-60.0096
1.536 MHz
96
62.496249
60.016
1.544 MHz
193
125.007499
60.0024
2.048 MHz
256
124.9925
-60.0096
4.096 MHz
512
62.496
-60.0096
8.192 MHz
1024
62.49624
-60.0096
Note:
PPM frame length error is calculated from ideal frame frequency.
Table 242.
Jitter Definitions
Jitter Type
Jitter Definition
Period Jitter (Pj):
Cycle-to-Cycle Jitter (Cj):
Wander-or-Accumulated Jitter (Aj):
Table 240.
HSS Tx/Rx Clock Output Frequencies and Associated Jitter Characterization
HSS Tx/Rx Clock
Output Frequency
Pj Max. (ns)
Cj Max. (ns)
Aj Max. (ns)
Note:
For jitter definitions, see
Table 242 on page 736
.
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