[OpenSIPS-Users] 502 Bad Gateway events leads to calls being rejected with 480 Temporarily Unavailable

solarmon solarmon at one-n.co.uk
Mon Jun 8 10:55:06 EST 2020

Hi Diptesh ,

Thanks for your reply.

Apologies, I'm using the term 'blacklist' to generally mean that the
endpoints are not available.

Also, the 502 Bad Gateway is response to an INVITE, not SIP OPTIONS,
returned by the far end and the ITSP is just passing that back to us,
because the call has failed. For such call failures, I'm not expecting for
the dispatcher endpoints to be marked as unavailable for routing.

I am not using, or have not set, the '*ds_define_blacklist (str)*' option
in my dispatcher module config.

My probing mode is:

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

I'm not seeing anything in the logs regarding the dispatcher nodes going
into Probing mode - should there be logs for that, or can it be enabled to
be logged?

When I check the endpoints with ' opensipsctl dispatcher dump' they always
seem to be '*Active*' - so it is either they are like that, or they
may have only been in '*Probing*' mode very briefly. Again, I was hoping to
see mode/state change in the historical logs.

In my *opensips.cfg* (which was created for me) I can see the following
code, which looks like this is where it is introducing this behaviour in

        xlog("[$ci] call failed to established with $T_reply_code code\n");


        if (t_was_cancelled()) {
                t_reply("487","Request cancelled");

        # any failure indication ?
        if ( t_check_status("[56][0-9][0-9]")
        || (t_check_status("408") && t_local_replied("all"))
        ) {
                xlog("[$ci] destination $rd failed  with $T_reply_code ->
retry\n ");

               * ds_mark_dst("p");*

                if ( ds_next_domain() ) {
                        xlog("[$ci] using new destination <$rd>\n ");

                        # send it out again
                } else {
                        xlog("[$ci] no other destination to retry\n ");
                        t_reply("503","Service not available");

        # if call failure, allow the reply to propagate to caller

Thank you for the tip about the  'modparam("dispatcher",
"options_reply_codes", "502")' option. I will try that if it is not
recommend to change the above code.

Thank you.

On Mon, 8 Jun 2020 at 10:47, Diptesh Patel <diptesh.patel at ecosmob.com>

> Hello Solarmon,
> Need some clarification on term blacklisting, Are you using the blacklist
> for Probing Mode of destination? or Are you using the *'ds_define_blacklist
> (str)' *parameter. If you are not using the blacklist parameter then
> below information help you. It is great if you share your script snippet
> and output of *'opensipsctl dispatcher dump'* which shows you the current
> status of your destinations.
> If you are getting success(200 OK) response on OPTIONS then it is not
> possible that you got a negative response from a destination and it will
> not be blacklisted(probing mode) in dispatcher until you blacklist(probing
> mode) from the script using 'ds_mark_dst()' exported function. I doubt that
> you are also getting '502 Bad Gateway' on OPTIONS which is sending to the
> destination to check the availability.  If It is right and you want to add
> the 502 response as a good response for OPTIONS. you can add the 502 as *'modparam("dispatcher",
> "options_reply_codes", "502")'.*
> Thanks & Regards
> *Diptesh Patel*
> Software Developer
> Ecosmob Technologies Ltd,
> Ahmedabad
> Mo:*+919898962659*
> On Mon, Jun 8, 2020 at 2:24 PM solarmon <solarmon at one-n.co.uk> wrote:
>> Hi,
>> I'm trying to understand whether this is the correct or expected
>> behaviour.
>> We have two destinations configured in Dispatcher.
>> What I am noticing is that when we receive 502 Bad Gateway messages
>> (logged as ("call failed to established with 502 code") from both
>> endpoints. After both endpoints have returned 502 Bad Gateway, opensips
>> pass back 503 Service Unavailable back to the originating endpoint of the
>> call. However, subsequent calls are being immediately rejected with 480
>> Temporarily Unavailable (logged as "failed to find an available
>> destination, rejecting") for a period of time.
>> It seems that opensips is blacklisting the Dispatcher endpoints because
>> of receiving the 502 Bad Gateway messages. Is this the correct/expected
>> behaviour? I would have thought the blacklisting should be based on the SIP
>> OPTIONS sent to the Dispatcher endpoints.
>> I do not currently see any issues with SIP OPTIONS to these endpoints so
>> I'm confused as to why they are seemingly blacklisted.
>> If this is the correct/expected behaviour, can it be changed to only
>> blacklist based on the SIP OPTIONs pings?
>> Thank you.
>> _______________________________________________
>> Users mailing list
>> Users at lists.opensips.org
>> http://lists.opensips.org/cgi-bin/mailman/listinfo/users
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