Nortel Networks 1000 - Manual (Page 390)

390 NT6D80 MSDL card
The MSDL uses the MSDL receive interface to communicate with the
system. The MSDL card receives packetized data from the I/O equipment
over the MSDL ports. This data is processed by the MSDL handler and
sent to the appropriate function.
The flow control mechanism provides an orderly exchange of transmit
and receive messages for each operation. Each operation has a number
of outstanding messages stored in buffers waiting to be sent to their
destinations. As long as the number of messages does not exceed the
threshold specified, the messages queue in the buffer in a first-in-first-out
process.
If the outstanding number of messages for an operation reaches the
threshold, the flow control mechanism informs the sender to wait until
the number of messages is below the threshold before sending the next
message.
If buffer space is not available, the request to send a message to the
buffer is rejected and a NO BUFFER fault indication is sent.
Engineering guidelines
Available network card slots
The number of available network slots depends on the system option, the
system size, and the number of available network slots in each module for
the selected system option.
Some of these network card slots are normally occupied by Network cards,
Superloop Network cards, Conference/TDS, and others, leaving a limited
number of unused slots for MSDL and other cards.
Card mix
A system that exclusively uses MSDL cards can support up to 16 such
cards, providing 64 ports. These ports can be used to run various
synchronous and asynchronous operations simultaneously.
The system also supports a mix of interface cards (MSDL, DCHI, and
ESDI for example). However, using multiple card types reduce the number
of cards and ports available.
Address decoding
The MSDL card decodes the full address information received from
the system. This provides 128 unique addresses. Since MSDL ports
communicate with the CPU using a single card address, the system can
support 16 MSDL cards providing 64 ports.
The MSDL card addresses are set using decimal switches located on the
card. These switches can select 100 unique card addresses from 0 to 99.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
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