7 Sep
2017
7 Sep
'17
3:56 p.m.
But the issue with TCP is the same. On
failover/restart (or completly
down in your case), the TCP session is lost, and non recoverable
assuming NAT. AFAIK there is no solution.
It's a pitty, my robust mind tells me, that there is no way to solve
it clearly, without stupid "crutches".
But I still hope, that there is a solution to it - I don't want to
move away from my idea.
Guys, the question is still opened, if someone can suggest solutions,
I will be glad to read it.
2017-09-07 13:05 GMT+03:00 Donat Zenichev <donat.zenichev(a)gmail.com>om>:
Having a
similar setup with failover for the loadbalancers, I take for
granted that TCP/TLS will fail in case of a failover (but UDP will keep
working after failover due to the stateless nature of it).
Well, your routing servers use PJSIP for NAPTR resolving?
If so, how have you made it working?
I mean, did you find a solution for TCP connections?
2017-09-07 11:03 GMT+03:00 Donat Zenichev <donat.zenichev(a)gmail.com>om>:
Hi.
Recently I've come across with TCP connection problem.
The topology is as following:
DNS srv load balancer - two kamailio proxy servers - one routing server.
Client appeals to NAPTR record like: sip.domain.com
So dns returns one of the proxy servers to client (depending on
weight/priority). Now both kamailio have the same priority and weight (the
goal is load balancing).
Routing server (now it is asterisk) working with chan_pjsip.so, that
supports NAPTR/SRV records.
He is able to resolve Record-Route / Route headers with value -
sip.domain.com (that proxy servers add to record-route headers while
relaying requests to him).
This topology is done to support present dialogs, even if proxy that
recently processed it, is dead.
But the problem comes, when routing server (asterisk) sends in-dialog
requests to the proxy, that wasn't used to establish the dialog.
Example, routing server obtains 200 OK from endpoint (relayed by
kamailio1 to him) and he sends back ACK, but not to the kamailio1, he sends
it to kamailio2 (because he resolves NAPTR sip.domain.com and gets ip of
second kamailio). Kamailio2 processes the request as usual, because both
kamailio have the same db for dialog module, but when he tries to relay the
request to endpoint, he gots the error:
ERROR: <core> [tcp_main.c:4070]: handle_tcpconn_ev(): connect
XXX.XXX.XXX.XXX:52185 failed
The port that kamailio2 tries to use to relay the ACK, is port that
endpoint used to establish the dialog with kamailio1 and actually his TCP
connection is now established with kamailio1.
So kamailio2 tries to use the same port and gets the error.
And this is proper behavior I think.
There is no problem with UDP transport.
Has anyone seen the similar problem? That indeed is not a problem, but
proper behavior.
--
--
BR, Donat Zenichev
Wnet VoIP team
Tel: +380(44) 5-900-808
http://wnet.ua
--
--
BR, Donat Zenichev
Wnet VoIP team
Tel: +380(44) 5-900-808
http://wnet.ua