Hi Bogdan!
Good news. How are the DNS lookups done in detail? E.g. the following setup:
t_relay to domain.com:
@domain.com
NAPTR 90 50 "s" "SIP+D2T" "" _sip._tcp.domain.com.
NAPTR 100 50 "s" "SIP+D2U" "" _sip._udp.domain.com.
@_sip._tcp.domain.com.
SRV 0 0 6060 sip1.domain.com.
SRV 1 10 6060 sip2.domain.com.
@_sip._udp.domain.com.
SRV 0 0 6060 sip1.domain.com.
SRV 1 10 6060 sip4.domain.com.
sip1.domain.com A 1.2.3.4
sip2.domain.com A 2.2.3.4
sip2.domain.com A 2.2.3.5
sip4.domain.com A 4.2.3.4
Is the following assumption correct?
1. lookup NAPTR domain.com
2. lookup SRV _sip._tcp.domain.com
3. lookup A sip1.domain.com
4. request to 1.2.3.4; if failure
5. lookup A sip2.domain.com
6. request to 2.2.3.4; if failure
7. request to 2.2.3.5; if failure
8. lookup SRV _sip._udp.domain.com
9. (sip1 cached) send request to 1.2.3.4; if failure
10. lookup A sip4.domain.com
11 request to 4.2.3.4; if failure
12 reply error
regards
klaus
Bogdan-Andrei Iancu wrote:
Hi everybody,
OpenSER 1.2.0 has now the capability to do DNS based failover, according
to RFC3263 (http://www.ietf.org/rfc/rfc3263.txt).
The SIP resolver was enhanced to to be able to save and resume later the
DNS queries in order to get all possible IP destinations. The resolving
process is step-by-step done (get next IP only on demand) to minimize
the total number of DNS queries. So having this support does not imply,
in normal processing, more load on the DNS server. Additional queries
are done only when needed (after failure detected).
The scanning for new IP destinations is done by the SIP resolver on all
DNS levels: NAPTR, SRV, A.
Both core and TM are using this new feature.
In core, the stateless forwarding can do only DNS-based failover at
transport level (if no egress interface found or send operation
failed due whatever reason).
In TM, the DNS-based failover is extended to transaction level. If the
transaction completes with 503 or 408 with no reply, automatically, a
new branch will be fork if any destination IP can be found by the DNS
resolver.
Read more here http://www.openser.org/docs/modules/1.2.x/tm.html#AEN103
For controlling this feature use:
- newly added core parameter "disable_dns_failover" - use to
generally disable the DNS-based failover. By default is false.
- in TM, t_relay() take a new flag for turning off the DNS-based
failover. This setting is per transaction. By default, the failover is
done.
Any feedback is appreciated.
regards,
Bogdan
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Klaus Darilion
nic.at
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