Inbound trunk selection

[nonny]

Hi guys

Where you have multiple trunk DNs with the same IP for an external gateway, when a call comes in, how does SIP Server determine which Trunk to process the call on?

For Outbound the prefix option is used with the priority option.  But what about for inbound?

[cavagnaro]

? There is no such thing, who sends the call is the Mediagateway and SIP Server only allows communication because one trunk at least has its ip address configured and is marked as allowed. You could even override that by setting sip server to allow any Inbound communication.

[nonny]

Yes but what if multiple trunks have that ip configured?  Which Trunk gets used?

[cavagnaro]

There is none used...those are logical links, only software, not as ISDN/R2 or any phisical connection

[nonny]

Bit confused then.  SIP Server shows messages similar to "trunk xxxxx is associated with..." for inbound calls.  If I disable the one displayed, the next call shows a different trunk associated in the log.  Where is that decision made?

[cavagnaro]

That is only to show which Trunk is allowing communication with that MG.
I'd say it is creation order...not sure and doesn't matter...again...
Trunks are used mostly important for Outgoing calls, where you can do priorization, balancing, configuration on how to communicate (REFER or not, etc) with the MG...
For Incoming, as explained before, only allows incoming IP and that is it.

What are you trying to do? Why is this a matter?

[nonny]

Running some field validation testing requested by Genesys.  One test case requires specific trunk configuration.  We have 8 trunk DNs for various reasons so I need to identify which Trunk will be used to make that configuration change against but leave the others as is for the rest of the environment.

[cavagnaro]

If you have 8 trunks with same IP Address...means maybe each one has a different prefix (AGAIN! used for outgoing calls only!)?
If your problem is against your MG then for INBOUND you change on MG settings and SIP Server will adequate (any trunk) to those settings.

If your problem is outgoing, then change only on the trunk associated with the prefix you are testing.

If you can't understand this simple architecture you will have a enormous headache ahead.

I think there is no more to say, repeating same answer over and over ahead will not change the result

[Fra]

[quote author=cavagnaro link=topic=8832.msg39363#msg39363 date=1431116088]
There is none used...those are logical links, only software, not as ISDN/R2 or any phisical connection
[/quote]
This is incorrect.
The inbound trunk selection works in this way:
- SIP Server tries to match the 'Via' header of the incoming INVITE with the 'contact' option value of the trunk DNs configured.
- If there are multiple trunk DNs with the same 'contact' option value, then any of them can be selected.

I assume that it may eventuallyselect the trunk DN with the lowest DBID, as it reads and store in memory the CME config objects sequentially, but that's just a speculation.

Fra

[cavagnaro]

Hehehe well reading only that of course is incorrect. My context was answering his concept to compare with physical interfaces. I explained better later.

[Fra]

[Anrew Livingston]

One further wrinkle to clarify on this.  What does this do to trunk capacity?  Just like the OP, I have multiple trunks setup with the same contact IP address (with different prefixes for outbound dialing and transfers), but if you can't specify which trunk inbound calls are associated with, what does that do to capacity limits?

If for example, on trunk_1 I want to set capacity=100 for Outbound calls, but then SIP server associates 90 inbound calls to Trunk_1, am I limited to 10 outbound calls then?

I know I can set capacity-limit-inbound=true but that looks like it only starts rejecting inbound calls after the capacity is reached.

Is there a better way to handle this?

http://docs.genesys.com/Documentation/SIPS/8.1.1/Dep/TrunkCapacity#Capacity_Control_of_Incoming_and_Outgoing_Calls

[victor]

To answer your question, yes, you would only have 10 trunks left. The easiest way is to stop doing hybrid setup, if your outbound is expected to use high percentage of the trunks used for inbound as well as for outbound.

Depending on your setup, if you hit the limit, T-Server would be be able to tell you that you are out of trunks, and you would start receiving SIT errors.