[Serusers] rewriting to a dns domain

[Rolf Unger]

As far as I know there are different options for load-balancing.
I even saw some modules for load balancing. But it is a bit tricky
to get this sorted out, because many of the load-balancing options
think of load balancing between several ser servers or in other words
having the ser servers as target of the load balancing process.

While I am looking for a load balancing of requests to a remote sip
server.

I thought that the SRV feature of the DNS system is quite old and long
time established, so I expected that ser would be able to send and
evaluate such a request to the DNS.
There would be nothing special to do for ser, all would be done in the
DNS with the same roud-robin mechanism that works for MX or A records.

You will read between the lines that I am more familiar with DNS than
with ser, so I tend for this kind of solution. But it seems that I have
to look into the source code of ser, to figure out in which way the dns
lookup is done (or maybe I run a tcpdump on the dns port 53, to check
what's happening).

Thanks anyway, Rolf.

On Tue, 22 Apr 2008, Miklos Tirpak wrote:
> I think load-balancing was introduced in version 2.0, so there is no way 
> to configure it in 0.9.x.
> 
> In 2.x, you need to enable it explicitly:
> dns_srv_lb=1
> 
> Regards,
> Miklos
> 
> On 04/18/2008 06:06 PM, Rolf Unger wrote:
> >Hello list users,
> >
> >i want to use ser as a load balancing proxy for some PSTN
> >gateways that I have in use.
> >My idea is to use the rewritehost() core function and DNS SRV
> >entries to accomplish this. But it seems that ser is doing a 
> >A record lookup if I simply replace the host with my domain
> >"mynet.interx":
> >
> >  if ( ... ) {
> >     rewritehost("mynet.interx");
> >     t_relay();
> >  }
> >
> >Ser is running on the same host (89.49.16.54) as the authorative
> >nameserver for the mynet.interx domain.
> >
> >dig shows that the DNS files are configured in the right way for
> >load balancing, but I just can't find a way to make ser as a dns client
> >work like dig.
> >
> >If I use "_sip._udp.mynet.interx" it will complain about a bad name.
> >Well he is partly right, underscores are not allowed in domain names.
> >
> >And if I use only the domain in the rewrite command it will contact
> >the IP of the nameserver of this domain. Or in other words it will send
> >the messages to itself.
> >
> >Using directly rewritehost("sip1.mynet.interx") doesn't help me,
> >because it wouldn't do load balancing.
> >
> >How can I convince ser (version 0.9.6) to use the correct lookup
> >method for the DNS?
> >
> >Any hints are appreciated ...
> >
> >Thanks, Rolf.
> >
> >----------------------------------------------------------------
> >
> >; <<>> DiG 9.2.4 <<>> -t SRV _sip._udp.mynet.interx
> >
> >;; QUESTION SECTION:
> >;_sip._udp.mynet.interx.      IN      SRV
> >
> >;; ANSWER SECTION:
> >_sip._udp.mynet.interx. 21600 IN      SRV     0 50 5060 sip3.mynet.interx.
> >_sip._udp.mynet.interx. 21600 IN      SRV     0 50 5060 sip1.mynet.interx.
> >
> >;; AUTHORITY SECTION:
> >mynet.interx.         21600   IN      NS      mynet.interx.
> >
> >;; ADDITIONAL SECTION:
> >sip1.mynet.interx.    21600   IN      A       89.49.16.50
> >sip3.mynet.interx.    21600   IN      A       89.49.16.51
> >mynet.interx.         21600   IN      A       89.49.16.54
> >
> >_______________________________________________
> >Serusers mailing list
> >Serusers at lists.iptel.org
> >http://lists.iptel.org/mailman/listinfo/serusers

-- 
 CoolSwitchIP wins Best Product of Show Award in Los Angeles! (Sept 2007)

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  Rolf Unger                  ._---_;
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