Specifications

Retransmission Parameters Reference Manual (MGCP/NCS Version)
Mediatrix 4100
89
Retransmission Parameters
Retransmission is a method of error control in which hosts receiving messages acknowledge the receipt of
correct messages and do not acknowledge the receipt of incorrect messages. The lack of acknowledgement
is an indication to the sending host that it should transmit the failed message again.
 To set Retransmission information:
1. In the ncsMIB, locate the ncsRetransmission group.
This group contains the retransmission information to set.
2. Set the following variables:
Table 70: NCS Retransmission Information
Variable Description
ncsRetransmissionAlgorithm Retransmission algorithm used.
• static(0)
The retransmission period stays the same.
Ex.: Period of 500 ms. The following retransmissions
will be at 500 ms, 1000 ms, 1500 ms, etc.
• exponential(1)
The retransmission period is doubled at each period.
Ex.: Initial period of 500 ms. The retransmissions will be
at 500 ms, 1000 ms, 2000 ms, 4000 ms, etc.
• exponentialWithJitter(2)
The retransmission period is exponentially calculated
with a random weighting factor varying from 88% to
112% of the calculated period.
Ex.: Initial period of 500 ms.
Period = (Period x 2) * (Random value (0 to 24) + 88) /
100
Period2 = (Initial period x 2) * (Random value (0 to 24)
+ 88) / 100
etc.
Default Value: exponentialWithJitter
ncsRetransmissionInitialPeriod Retransmission initial period in ms.
Default Value: 200
ncsRetransmissionMaxPeriod Retransmission maximum period in ms. Shall be greater than
or equal to the retransmission initial period.
Default Value: 30000
ncsRetransmissionDisconnect
Timeout
Time elapsed (in ms) at which an endpoint becomes
disconnected.
Default Value: 20000
ncsRetransmissionSuspicion
Threshold
Number of retransmissions at which an endpoint may actively
query the name server to detect the possible change of the
Call Agent's interfaces.
Default Value: 7