Chapter 3 System Features
PSAX System Software Features
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PacketStar
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PSAX 2300 Multiservice Media Gateway User Guide
, Issue 1
Release 9.0.0
encodes the header address within the same 10-nibble header space of stan-
dard ATM cells. In addition, it avoids the extra delay (detrimental to CBR
traffic) required of multiple header-encoding schemes.
In practice, to tolerate 2-bit random errors or 5-bit burst errors requires set-
ting up 526 addresses for each channel. This is not a serious constraint
because noisy low-speed links will likely only be used to support a small
number of users.
Finally, given the ability to deliver cells, the payload can now be FEC-pro-
tected on each virtual circuit, depending on the error tolerance of the appli-
cation at the service-specific convergence sublayer (SSCS). Figure 3-10
shows the LANET frame structure.
The LANET subframe functions in the following ways:
•
The timely arrival of the header patterns is used as a confidence check,
confirming that the system is properly synchronized.
•
In the event of synchronization loss, a PSAX system can easily seek and
resynchronize to the regular appearance of the simple header patterns.
See the description for “Forward Error Correction” on page 3-40 for a list of
modules supporting LANET.
Figure 3-10. LANET Frame Structure
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