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Intel
®
IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
September 2006 DM
Order Number: 252480-006US 457
High-Speed Serial Interfaces—Intel
®
IXP42X product line and IXC1100 control plane
processors
17.6 HSS Supported Framing Protocols
The following sections provide an overview of some Framing Protocols supported by
each of the two IXP421, IXP423 and IXP425 network processors’ HSS interfaces 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.
17.6.1 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 timeslots,
each timeslot is a byte in size. As there are 24 timeslots per frame, T1 can carry 24
channels.
Figure 86 and Figure 87 illustrate a typical T1 frame with an active high frame sync
(level) and a positive edge clock for generating or sampling data. The HSS clock and
frame pulse can be programmed to be either HSS outputs or HSS inputs. An offset can
be 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.
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 159. Jitter Definitions
Jitter Type Jitter Definition
Period Jitter (Pj):
Cycle-to-Cycle Jitter (Cj):
Wander-or-Accumulated Jitter (Aj):
Table 158. HSS Frame Output Characterization
averag
e
ii
PeriodPeriodPj −=
)()(
)()1()( iii
PjPjCj −=
+
∑
=
i
i
PjAj
)(