[Spce-user] Alternative RTP Interface

Robert Johnson robert.j at bendtel.com
Tue Jul 31 12:59:45 EDT 2018

I had seen that, and specifying the rtp interface by setting by setting 
the rtp_interface parameter in the domain preferences does indeed work, 
but that's not exactly what I'm looking for.

Allow me to elaborate on what I'm attempting to accomplish.

I would like for a client to perform an SRV look up, the look up would 
return two servers

dig srv _sip._udp.spce1.domain.net

_sip._udp.spce1.domain.net. 86400 IN SRV    10 100 5060 spce1a.domain.net.
_sip._udp.spce1.domain.net. 86400 IN SRV    20 100 5060 spce1b.domain.net.

spce1a.domain.net is the primary interface within SPCE. Here is a 
snippet from /etc/ngcp-config/network.yml

       hwaddr: ...
       ip: ...
       netmask: ...
       - web_ext
       - sip_ext
       - rtp_ext
       - ssh_ext
       - web_int

spce1b.domain.net is the secondary interface within SPCE. Here is a 
snippet from /etc/ngcp-config/network.yml

       hwaddr: ...
       ip: ...
       netmask: ...
       - sip_ext_incoming
       - rtp_ext
       - ssh_ext

Let's say that spce1a.domain.net is unreachable for some reason -- (The 
ISP is down, there's a DDOS, There's a routing issue, etc)

When the client registers on the spce1b.domain.net interface, SPCE is 
unaware that there is an issue with the spce1a.domain.net interface and 
presents the IP address of spce1a.domain.net as the contact ("c=") SDP 
parameter. Because there is an issue preventing communications on 
spce1a, the call will set up, but there will be an audio issue (the 
severity of the audio issue would be relevant to the type of issue with 

I'm hoping that there is a way that SPCE will assign the IP address of 
either spce1a or spce1b in the SDP contact depending on if the client 
registers against spce1a or spce1b - That is, A client registered 
against spce1a get's spce1a as the SDP contact and a client registered 
against spce1b get's spce1b as the SDP contact.

Hope this helps.

Thank you!

On 07/30/2018 11:51 PM, Daniel Grotti wrote:
> Hi,
> yes that's possible.
> Please check this out: 
> https://www.sipwise.com/doc/mr5.5.5/spce/ar01s12.html#extra-sip-rtp
> Cheers,

More information about the Spce-user mailing list