Multiplexer User's Guide
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5.3 Implementing version control
The TE initiates the version check by sending the Test command via the multiplexer control
channel DLCI 0 (with TEMUX_Version).
As specified in the GSM recommendation 07.10 (chapter 126.96.36.199.4) the opposite entity shall
respond with exactly the same value bytes.
The MS shall return the Test command response with the same contents for the verification
pattern. Hereafter the MS shall send a Test command message (with MSMUX_Version) to
the TE, and the TE shall respond with the same contents. After sending the response a
version compare is made on both sides. As a result, both sides shall agree upon the same
multiplexer protocol version.
When the MS realizes the implemented software but the TE does not respond correctly, the
following errors might occur:
The "Request Test" message is not sent from the TE:
No version check takes place. No retransmission for "Request Test" message is
triggered. The multiplexer starts with protocol version 1 because no version information
was exchanged between TE and MS.
The "Response Test" message is not sent from the TE:
No timer has been implemented for the non responding cases. If the response message
DLC_CONNECTEDWAIT4RESPONSE until another multiplexing related action takes
However, it is possible to send test commands with "any contents" (except for test messages
with the specific IEI for the version check). If a test command with "any contents" is sent, it
has to be sent back to the originator with the same contents.
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