Hello,
working on Kamailio SCSCF module, when I receive an INVITE the serving module should find the corresponding ICSCF to forward the INVITE. In order to do this it should perform a NAPTR query, followed by a DNS SRV query and a DNS A query.
In our case the serving has the following behavior: 1) it CORRECTLY make NAPTR query 2) it send an SRV query to resolve ICSCF service port having invalid response 4 times.
After 4 times, so 20 seconds, it sends INVITE message to ICSCF at default port 5060. SRV query contains a null name, shown as <Root> in Wireshark. Current DNS application (MyDNS) answer with a not implemented response.
I expect that the serving CSCF try to resolve the ICSCF making an SRV query and an A query to discover the service port and ip address using the domain returned by NAPTR query.
I have two questions: It seems that SRV query is not valid, because it's not based on SIP domain, do you think it's correct?
At least, is it possible to configure s-cscf to force an INVITE to be sent always to the same interrogating?
I attach a Wireshark dump
2013/12/13 Flavio Battimo flaviobattimo@gmail.com:
Hello,
working on Kamailio SCSCF module, when I receive an INVITE the serving module should find the corresponding ICSCF to forward the INVITE. In order to do this it should perform a NAPTR query, followed by a DNS SRV query and a DNS A query.
In our case the serving has the following behavior:
- it CORRECTLY make NAPTR query
- it send an SRV query to resolve ICSCF service port having invalid
response 4 times.
After 4 times, so 20 seconds, it sends INVITE message to ICSCF at default port 5060. SRV query contains a null name, shown as <Root> in Wireshark. Current DNS application (MyDNS) answer with a not implemented response.
I expect that the serving CSCF try to resolve the ICSCF making an SRV query and an A query to discover the service port and ip address using the domain returned by NAPTR query.
I have two questions: It seems that SRV query is not valid, because it's not based on SIP domain, do you think it's correct?
At least, is it possible to configure s-cscf to force an INVITE to be sent always to the same interrogating?
-- Flavio Battimo flavio.battimo@gmail.com fbattimo@meetecho.com skype: flaviobattimo
Not using ims modules I don't know if they do any dns internally. But speaking in general for kamailio, when sending out with t_relay() or forward(), if the SRV fails, the fallback is to do A query on hostname from R-URI and use default SIP port 5060.
If you wand us to try to help more, perhaps is better to provide syslog messages with debug=3 in kamailio.cfg.
Cheers, Daniel
On 13/12/13 11:58, Flavio Battimo wrote:
I attach a Wireshark dump
2013/12/13 Flavio Battimo flaviobattimo@gmail.com:
Hello,
working on Kamailio SCSCF module, when I receive an INVITE the serving module should find the corresponding ICSCF to forward the INVITE. In order to do this it should perform a NAPTR query, followed by a DNS SRV query and a DNS A query.
In our case the serving has the following behavior:
- it CORRECTLY make NAPTR query
- it send an SRV query to resolve ICSCF service port having invalid
response 4 times.
After 4 times, so 20 seconds, it sends INVITE message to ICSCF at default port 5060. SRV query contains a null name, shown as <Root> in Wireshark. Current DNS application (MyDNS) answer with a not implemented response.
I expect that the serving CSCF try to resolve the ICSCF making an SRV query and an A query to discover the service port and ip address using the domain returned by NAPTR query.
I have two questions: It seems that SRV query is not valid, because it's not based on SIP domain, do you think it's correct?
At least, is it possible to configure s-cscf to force an INVITE to be sent always to the same interrogating?
-- Flavio Battimo flavio.battimo@gmail.com fbattimo@meetecho.com skype: flaviobattimo
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
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Flavio Battimo