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B-23
Cisco BTS 10200 Softswitch Troubleshooting Guide, Release 5.0.x
OL-8723-19
Appendix B System Usage of MGW Keepalive Parameters, Release 5.0
Keepalive for Release 5.0 Maintenance Release 1.1 and Later
Scenarios with AUEP Message Retransmissions and No ACK
This section explains how the system handles MGCP message retransmissions and takes action when no
ACK is received from the MGW.
MGCP-RTO-MAX
shows how the system repeats the same AUEP message if an ACK is not received. The
period between subsequent retransmissions increases by a factor of two, but is limited to a maximum of
mgcp-rto-max
.
Tip
Terminology—Note that the first transmission is called the initial transmission. The second
transmission of the same AUEP message is called the first retransmission (or the first
retransmission).
Figure B-16
Example of Retransmission Timing (Upper Limit = mgcp-rto-max)
Note
See the additional information about
mgcp-t-tran
in the
“Initial Transmission Waiting Period
(mgcp-t-tran)” section on page B-21
Time
mgcp-t-tran
2*mgcp-t-tran
4*mgcp-t-tran
8
*mgcp-t-tran
KA attempt
(AUEP transaction)
AUEP,
initial
transmission
mgcp-rto-max
(default = 4 seconds)
16*mgcp-t-tran
mgcp-rto-max
(default = 4 seconds)
250022
AUEP,
2nd transmission
(1st retransmission)
AUEP,
3
rd transmission
(2nd retransmission)
AUEP,
4th transmission
(
3
rd retransmission)
AUEP,
5th transmission
(4th retransmission)
AUEP,
6th transmission
(5th retransmission)