Amtelco infinity series, Техническое руководство

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Layer 1 & Layer 2 Protocols • 7-8 •
The H.110 Basic Rate ISDN Board
This command takes the form TFxxtt where xx is the port number and tt
is the TEI number in the range 00-3F. This command does not
automatically place the data link in the multi-frame established state, but
instead puts it in the TEI assigned state. It is not necessary to issue this
command for an NT port, as the board will automatically reserve space for
a fixed TEI upon receiving a message with a TEI in the range of fixed
TEI’s. However, space can be reserved by the command before receiving
a message. This may be desirable, as fixed TEI’s count toward the limit of
seven TEI’s per port.
The application can request the removal of a TEI by issuing the TEI
removal command for an NT port. This command is of the form
TRxxtt ,
where xx is the port and tt is the TEI. If the TEI value is 127 or 7Fh, all
TEI’s on that port will be removed. If a TE port receives a request to
remove a TEI it will send a response message of the form
TRxxtt to the
application where xx is the port number and tt is the TEI value. If this
value is 7F, the request was to remove all TEI’s.
If there is a question of whether all TEI’s are currently valid, the
application can request a TEI check be performed by sending a command
of the form
TCxx where xx is the port number. This can only be done for
NT ports. If the check detects any TEI’s that are assigned to multiple
devices or that are not assigned, it will remove them. The application can
verify the validity of a TEI on a TE port by sending a command of the
form
TVxxtt . The NT on the far end will then initiate a TEI check
procedure. The TEI Check response can take one of two forms. The
default form is to include all TEI’s in a single TEI Check Response
message. The alternate form is for each TEI to be reported in a separate
TEI Check Response message. Either form is correct and central office
equipment should respond correctly to both, however, this may not be the
case with some older equipment, and so the option is provided.
The Layer 2 System Option command is used to control the Layer 2
behavior. This command takes the form
SSxy where x and y control the
first and second option and can take the values 0 or 1. The first option, if
set to 1 disables the timer TWAIT and therefore disables the automatic TEI
request for a TE port. The second option controls the form of the TEI