Datasheet

____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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 For AAL1/HDLC/RAW structured bundles: the Jitter_buffer_index value
is the number of the lowest
timeslot in the bundle. For example, if the bundle consists of timeslots 2, 4, 17 on port 3,
Jitter_buffer_index=0x2.

For unstructured bundles the Jitter_buffer_index valu
e is 0x0.
10.6.10.3 Jitter Buffer Status and Statistics
The CPU accesses the Jitter Buffer Status Table using the Jitter_buffer_index as described above. The status table
contains the current jitter buffer status (such as, the current jitter buffer level and its current state (OK, underrun or
overrun).
The status table also contains two variables, Minimal_level an
d Maximal_level, which report the minimum and
maximum fill levels of the jitter buffer since the last time the two fields were read (available for AAL1 and RAW
bundles only). These variables provide information about network packet delay variation. For example, using these
values, the CPU can calculate the margins from the top (Rx_max_buff_size)
and the bottom of the jitter buffer. If
there is margin, CPU software may want to reduce Rx_PDVT to reduc
e the latency added by the jitter buffer to the
incoming TDM data.
10.6.10.4 Jitter Buffer Response to Packet Loss and Misordering
The payload-type machines detect that a packet was lost by sequence number error. If a packet is lost,
conditioning data (specified by the receive software conditioning registers in section 11.4.12) is inserted i
nto the
jitter buffer in place of the lost data to maintain bit integrity (i.e. the number of bits that are inserted into the jitter
buffer must equal the number of bits that were transmitted by the far end).
If a packet is misordered in a RAW bundle (for example, the packet with the sequence number N arrives after the
packet with sequence number N+1) it is reordered by the RAW payload-type machine, and its data is inserted into
the appropriate location in the jitter buffer, assuming that the data in this location has not been transmitted to the
TDM port yet.
10.6.11 Queue Manager
Data flows through the TDMoP block in the following directions:
 TDM to Ethernet (implem
ented in HW)
 Ethernet to TDM (impl
emented in HW)
 TDM to TDM
(cross-connect, implemented in HW)
 TDM to CPU
 CPU to TDM
 CPU to Ethernet
 Ethernet to CPU.
These data flows are illustrated in Figure 10-49. Ea
ch data flow is described in a subsection below.