Alcatel 060170-10, Руководство пользователя

Страница: 38 / 430

Introduction
Page 2-4
Digital Signal Processors (DSPs), DIMMs and Available Channels
All digital VoIP daughtercards have four vocoder channels available per DSP chip. DSPs are
scalable in increments of three (in DSP DIMM modules) to better accommodate the needs of a
VoIP network, and to reduce costs since the number of DSPs required is based on the
number of simultaneous vocoder channels needed. DIMM stands for DSP Interface Manage-
ment Module (
not Dual Inline Memory Module).
Voice switching daughtercards, such as the VSD T1/E1 card, can contain up to 15 digital
signal processors running at 100 MIPS (millions of instructions per second), providing voice
processing functions for up to 60 DS-0s, or 60 Digital Service 0 channels (24 DS-0s are equal
to one DS-1, or T1, channel).
The number of populated DIMMs (DSPs) on the digital voice daughtercards determines how
many channels, which are bidirectional, are available on the card (e.g., 12 bidirectional chan-
nels per DIMM; or, a maximum of 60 bidirectional channels with 4 additional DIMMS). The
number of simultaneous channels available on a particular digital voice switching daughter-
card can be determined easily by counting the DIMMs on the card.
The illustration on the next page shows a VSD T1/E1 card fully-populated with standard DSPs
and additional DIMMs. As a minimum configuration, three DSPs come standard on the digital
cards to provide 12 channels (4 bidirectional channels per DSP); however, it is strongly
recommended that only fully-populated (128 MB, 60 channel) VSD daughtercards be installed
for the following reasons.
• Although a VSD with 12 channels (three std. DSPs) has two operational T1 ports that can
provide up to 48 bidirectional channels, only the first 12 simultaneous calls can be handled
per DSP; therefore, without additional DSPs (DIMMs) the 13th call and all subsequent calls
will be ignored completely, i.e., no dial, busy signal or comfort noise will be generated,
until either a channel becomes available, or additional DIMMs are installed.
• The installation of additional DIMMs, in effect, provides redundancy in the event of a DSP
failure.
♦
Notes
♦
There are no DIMMs on the VSA daughtercard per se,
only on the FXO or FXS grand-daughtercards with a
maximum of one channel each per port. See
Voice
Switching Daughtercard — Analog on page 2-19 for
more details.
DIMMs are not field upgradeable; however, the flash
memory on the boards is field upgradeable. The flash
memory must always match the image used or the
daughtercard will not function properly if at all. Contact
Alcatel’s Customer Support for details on obtaining the
appropriate flash and/or corresponding image upgrade.