Multiple SDP invites

Status
Not open for further replies.

hhijawi

New Member
Nov 10, 2020
13
0
1
36
Hi
I have an issue when connecting the endpoint with 3G connection. I see multiple SDP invites are sent from the endpoint and this delays the call start signal.
when I connect using WiFi I see only one invite and the call start signal is fast.
Attached sngrep output.

appreciate your help.
 

Attachments

  • 1.JPG
    1.JPG
    222.5 KB · Views: 23

atmosphere617

Member
May 19, 2018
31
4
8
It looks like freeswitch isn't getting the sip responses. Those packets with the extra ">>>" are retransmission and are sent when requests don't receive the reply the expect. Where are you running the packet capture?
 

hhijawi

New Member
Nov 10, 2020
13
0
1
36
it is running on the same FreeSWITCH server.
so you think that endpoint sends the INVITE and it does not receive the OK from the server?
could it be related to NAT?
 

atmosphere617

Member
May 19, 2018
31
4
8
Oh I assumed 45.147.* was the fs server b/c of the user-agent header. But yeah in this case it's pretty clear that sip stack isn't getting the response from the invite which is causing all those retransmission. Based on the 3g thing it's most likely network related. You could confirm this by running a pcap on the local network as well.
 

hhijawi

New Member
Nov 10, 2020
13
0
1
36
I tried another test with WiFi and I see the issue.
it happens if the line is idle for a few seconds.
I tried another test, end the call, and immediately start a new one, in this case, I don't see retransmission.
 

atmosphere617

Member
May 19, 2018
31
4
8
Sounds like a firewall may be closing the port. You most likely need to do some kind of UDP hole punching. Have you made sure "nat-options-ping" is enabled on the profile? I think you can turn it on per extension as well by enabling "Force ping".

If NAT pinging is already on you could also try enabling one of the "NAT hacks". You can turn these on in fusion by changing the value of "SIP force contact". Those set "sip-force-contact=NDLB-connectile-dysfunction" in the user directory. More on that here: https://freeswitch.org/confluence/display/FREESWITCH/NAT+Traversal

Otherwise you really need to get a pcap from the perspective of the UA to determine the root issue. You're really just guessing.
 

hhijawi

New Member
Nov 10, 2020
13
0
1
36
Thanks alot for your help,
I tried all NAT options, also nat-options-ping and rport are set but still with no luck.
I am developing an android application based on PJSIP, the only workaround which works for me is setting the UDP keepalive to 1 second, I don't think this is good.
I was using Asterisk and I did not see the issue.
I feel it is some configurations in FusionPbx.
 

DigitalDaz

Administrator
Staff member
Sep 29, 2016
3,071
577
113
Have you tried using TCP? Those SDPs look like they may be big enough to fragment the UDP packet.
 

hhijawi

New Member
Nov 10, 2020
13
0
1
36
yes, same for TCP.
the packet size is small, does not seem related to fragmentation

1610966640777.png
 
Status
Not open for further replies.