Indeed they are transmissions. The <<< and >>> indicate that in the screenshot (and the timestamps of the messages also strongly suggest it).

The responses come on the network, but kamailio/dispatcher is not getting them. Maybe they don't even get to kamailio (wrong UDP checksum, for example), maybe kamailio is dropping them (they're malformed or the Via is wrecked, for example) or maybe your config file is somehow dropping them. Maybe even it's something else.

With a pcap file, we may be able to narrow these multiple possibilities.

James

On Wed 25 Jun 2025, 08:42 Daniel-Constantin Mierla via sr-users, <sr-users@lists.kamailio.org> wrote:

Hello,

you have to send the pcap with the keepalive OPTIONS? The screen shots are not that useful for troubleshooting, it is some indication of retransmissions, but it cannot be asserted properly on the screenshot. Furthermore, the dispatcher.list output shows 183 timeouts, meaning that the gateways haven't responded to 183 keepalives till that moment.

Cheers,
Daniel

On 24.06.25 20:51, Pablo Oliver via sr-users wrote:

Hi there,

I'm new to Kamailio, and maybe this is a silly question.

I’ve set up Kamailio as a SIP proxy with two Asterisk servers acting as media services.

This is my configuration for the dispatcher module:

loadmodule "dispatcher.so"

modparam("dispatcher", "db_url", DBURL)

modparam("dispatcher", "table_name", "dispatcher")

modparam("dispatcher", "flags", 2)

modparam("dispatcher", "ds_ping_interval", 20)

modparam("dispatcher", "ds_ping_method", "OPTIONS")

modparam("dispatcher", "ds_probing_threshold", 5)

modparam("dispatcher", "ds_inactive_threshold", 5)

modparam("dispatcher", "ds_ping_latency_stats", 1)

modparam("dispatcher", "ds_probing_mode", 1)

modparam("dispatcher", "ds_ping_reply_codes", "class=2;code=403;code=488;class=3")

modparam("dispatcher", "ds_ping_from", SIPCALL)

I can see the SIP OPTIONS requests going from Kamailio to Asterisk and receiving 200 OK responses.

However, the dispatcher is still setting the IP (Inactive Probing) flag on the servers:

kamcmd dispatcher.list

{

 NRSETS: 1

 RECORDS: {

  SET: {

   ID: 1

   TARGETS: {

    DEST: {

     URI: sip:172.16.254.21:5060

     FLAGS: IP

     PRIORITY: 0

     LATENCY: {

      AVG: 0

      STD: 0

      EST: 0

      MAX: 0

      TIMEOUT: 183

     }

    }

    DEST: {

     URI: sip:172.16.254.20:5060

     FLAGS: IP

     PRIORITY: 0

     LATENCY: {

      AVG: 0

      STD: 0

      EST: 0

      MAX: 0

      TIMEOUT: 183

     }

    }

   }

  }

 }

}

So when I try to use ds_select_dst("1", "4"), it always fails.

Did I miss something in my configuration?

Thanks!

Regards,

Pablo.

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Kamailio Consultancy, Training and Development Services -- asipto.com

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