Hi All,
I tested the retransmission of INVITE message by the NIST stack, using the
TAHI SIP Conformance test package.
I got confused after looking at the pattern in which the NIST stack sends
retransmissions.
<snippet from test logs>
The call flow is below,
Sequence
NUT R PX1 UA1 OT1 OT2 REG DNS
No time | | | | | | | |
[01: 0.00|ICMP] |<----|-----| | | | | | Echo
Request
[02: 0.00|U ] |-----|---->| | | | | | Echo
Reply
[03:19.20|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED]:5060
[04:19.70|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED]:5060
[05:20.76|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED] :5060
[06:22.88|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED]:5060
[07:27.12|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED]:5060
[08:31.36|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED]:5060
[09:35.60|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED]:5060
[10:39.84|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED]:5060
[11:44.08|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED]:5060
[12:48.32|U ] INVIT |-----|---->| | | | | | INVITE
sip:[EMAIL PROTECTED] :5060
[13:51.20| ] |*****|*****|*****|*****|*****|*****|*****| Fire B
Timer
The judgement which TAHI performs for testing the RFC rules is below,
Judgment
Timer: INVITE MUST be retransmitted( No.1) after Timer A fired. Timer A:0
retransmit time:0.00
Timer: When Timer B fired, client INVITE retransmit No.1 has valid interval.
Timer B:0 retransmit time:0.00
Timer: INVITE MUST be retransmitted(No.2) after Timer A fired. Timer
A: 0.5retransmit time:
0.51
Timer: When Timer B fired, client INVITE retransmit No.2 has valid interval.
Timer B:0.5 retransmit time:0.51
Timer: INVITE MUST be retransmitted(No.3) after Timer A fired. Timer A:1
retransmit time: 1.06
Timer: When Timer B fired, client INVITE retransmit No.3 has valid interval.
Timer B:1 retransmit time:1.06
Timer: INVITE MUST be retransmitted(No.4) after Timer A fired. Timer A:2
retransmit time:2.12
Timer: When Timer B fired, client INVITE retransmit No.4 has valid interval.
Timer B:2 retransmit time:2.12
Timer: INVITE MUST be retransmitted(No.5) after Timer A fired. Timer A:4
retransmit time:4.24
Timer: When Timer B fired, client INVITE retransmit No.5 has valid interval.
Timer B:4 retransmit time: 4.24
Timer: INVITE MUST be retransmitted(No.6) after Timer A fired. Timer A:8
retransmit time:4.24
Timer: When Timer B fired, client INVITE retransmit No.6 has valid interval.
Timer B:8 retransmit time:4.24
Timer: INVITE MUST be retransmitted( No.7) after Timer A fired. Timer A:16
retransmit time:4.24
Timer: When Timer B fired, client INVITE retransmit No.7 has valid interval.
Timer B:16 retransmit time:4.24
Timer: INVITE MUST be retransmitted(No.8) after Timer A fired. Timer A:32
retransmit time: 4.24
Timer: When Timer B fired, client INVITE retransmit No.8 has valid interval.
Timer B:32 retransmit time:4.24
Timer: INVITE MUST be retransmitted(No.9) after Timer A fired. Timer A:64
retransmit time:4.24
Timer: When Timer B fired, client INVITE retransmit No.9 has valid interval.
Timer B:64 retransmit time:4.24
Timer: INVITE MUST be retransmitted(No.10) after Timer A fired. Timer
A:0.5retransmit time:
4.24
Timer: When Timer B fired, client INVITE retransmit No.10 is timer missing.
Timer B: 0.5 retransmit time:4.24
Timer: Client sent INVITE
Timer: Client INVITE retransmit stopped after Timer B fired.
Timer: Client MUST NOT send ACK after Timer B fired.
</snippet>
The pattern of the retransmit time should start with T1 sec(500 ms by
default in NIST stack) and should go
till T2(64 * T1) as per the RFC. The pattern of the retransmit time is not
as per our requirement, i.e.
0.00, 0.51, 1.06, 2.12, 4.24, after it remains the same. Also I wonder how
there is a possibility for 10 retransmissions
while there can be only 7 retransmissions with the configured value of T1=
0.5 and T2=64*0.5=32.
I tested the simplecallsetup example, that comes along with the NIST stack,
for retransmission using the loopback interface. I observed that the time at
which the INVITE's and it's retransmissions were sent, also showed the same
pattern and also
there were 10 retransmissions.
The time pattern is below,
1188482985142
1188482985649
1188482986709
1188482988819
1188482993059
1188482997299
1188483001543
1188483005783
1188483010023
1188483014263
1188483018503
Is it an issue (or) am I missing any configurations to be performed ? Please
correct me and advise me
accordingly. Also let me know if it is a known problem.
Thanks in advance,
Regards,
Nabeel
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