Specifications

Chapter 2 – Configuration Commands
Multi-Tech Systems, Inc. AT Commands for EDGE (E1) Modems (S000474A) 42
<tcpIrt> Initial Retransmission Timeout (IRT)
1....60 This parameter determines the time (in seconds) the TCP/IP stack will
wait before starting the first retransmission of packets during the initial
connection establishment phase. Default = 3 (This is the factory default value
and will be restored to 5200 with AT&F. It is also a powerup default value
which is not stored at power down).
The TCP protocol ensures the retransmission of packets several times at
increasing intervals until some upper limit is reached.
This mechanism prevents packet loss and serious congestion problems.
Parameter is global for the ME and non-volatile. Use of default value is
recommended.
If changed the new value takes effect the next time you start an Internet
service with AT^SISO.
<tcpMr> Maximum Number of Retransmissions (MR)
1....30. Default = 10 (This is the factory default value and will be restored to 10
with AT&F. It is also a powerup default value which is not stored at power
down).
This parameter determines the maximum number of times to retransmit TCP
packets while the service is in connected state. If the service is still connecting
(connection setup) another algorithm applies.
The value set with <tcpMr> will be assumed as default for the <srv-ParmTag>
"tcpMR" when a new service profile is created with AT^SISS. In each service
profile, you can set another "tcpMR" value which has precedence over the
global value set with AT^SCFG. Existing service profiles are not affected when
you change the global value via AT^SCFG.
Parameter is global for the ME and non-volatile. Use of the default value is
recommended.
<tcpOt> Overall TCP Timer for outstanding connections (tcpOT)
1...6000. Default = 6000 (This is the factory default value and will be restored
to 6000 with AT&F. It is also a powerup default value which is not stored at
power down).
This parameter specifies the number of seconds to wait before closing a
connection if TCP/IP packets are not acknowledged.
Setting the maximum value is practically equivalent to deactivating the tcpOT
mechanism because the maximum time would never be reached by the
TCP/IP stack.
The value set with <tcpOt> will be assumed as default for the <srv-ParmTag>
"tcpOT" when a new service profile is created with AT^SISS. However, in each
service profile, you can set another "tcpOT" value which has precedence over
the global value set with AT^SCFG. Existing service profiles are not affected
when you change the global value via AT^SCFG.
Parameter is non-volatile. Use of default value is recommended.
<tcpSack> Selective Acknowledge (SAck)
This parameter concerns a set of TCP extensions to improve performance and
to provide reliable operation. It defines new TCP options for scaled windows
and timestamps, which are designed to provide compatible interworking with
TCPs that do not implement the extensions.
The set of TCP extensions to improve performance is described in RFC 1323.
The value set with <tcpSack> enables or disables the set of TCP extensions.
Parameter is global for the ME. Use of power up value is recommended.
0 Disable set of TCP extensions.
1 Enable set of TCP extensions. Default (This is the factory default value
and will be restored to 6000 with AT&F).