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Document History
Revision#
Version Date
Comments
04
July 2011
External Route Lookup enhancement
05
Sep. 2011
RTID field update
06
June 2015
Updated for release 5.10.2
Refer to www.dialogic.com for product updates and for information about support policies, warranty
information, and service offerings.
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Table of Contents
INTRODUCTION ............................................................................................................................................ 4 1.
1.1 Overview ..................................................................................................................................................... 4
1.2 System Architecture .................................................................................................................................... 4
SIP ROUTING SERVER INTERACTION ............................................................................................................. 6 2.
2.1 Request to Routing Server .......................................................................................................................... 6
2.2 Possible Response Formats ......................................................................................................................... 6
Format 1.................................................................................................................................................. 6 2.2.1
Format 2.................................................................................................................................................. 7 2.2.2
BASIC CALL FLOW ......................................................................................................................................... 8 3.
RSG CALL FLOW ............................................................................................................................................ 9 4.
CDR INFORMATION ..................................................................................................................................... 10 5.
5.1 Call Tracing and Routing Dips .................................................................................................................... 10
ALARMS....................................................................................................................................................... 11 6.
CONFIGURATION ......................................................................................................................................... 12 7.
7.1 PE Mapping ............................................................................................................................................... 12
ENVIRONMENT VARIABLES ......................................................................................................................... 13 8.
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Introduction 1.
1.1 Overview
The Control Switch can be configured to provide routing, based on routing information retrieved from
an external SIP routing server. To implement this capability the Routing SIP Gateway (RSG) is used. RSG
sends an Invite message to an external SIP routing server, using the routing information in the 3xx
messages.
CS facilitates external routes to both the trunk groups and the route list mapping mechanism in the
Policy Engine (PE). Because of this, the external SCP does not need to be aware of trunk groups or route
list identities. The external route mapping is provisioned in the PE. The SIP routing process is performed
exactly in the same way as the regular routing. RSG is a licensed entity, and may require separate
hardware depending on rate of queries sent to the SIP SCP.
1.2 System Architecture
The RSG is an integral component of the CS, used when an external SIP routing server needs to be
queried.
The SIP routing solution involves the following elements:
Call Processing Element (CCE). IP/TDM Call Processing element.
Service Execution Element (SEE). After dipping with the Policy Engine (PE), the SEE interacts
with the LSG that queries the RSSN.
Policy Engine (PE). Provides the service trigger information for identifying whether or not there
is a need for SIP-based SCP interaction. PE also provides the mapping for external IDs returned
from external route server.
Routing SIP Gateway (RSG). Communicates the transaction messages between the CS and
RSSN.
External Route Server (RSSN). Provides the external routing information. RSG requests routes
over SIP from the routing server. The routing server responds with a list of IDs (trunk groups or
route lists) that the CS uses for routing or re-routing. The routing server response could also
contain an optional RTID field that is sent it to SEE, and SEE reports the RTID value to EC.
EMS. EMS manages all the elements of the CS. It provisions the PE with routing information and
other necessary required mappings, and allows the dynamic provisioning of the service nodes.
The following figure depicts the system architecture.
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Figure 1: System Architecture
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SIP Routing Server Interaction 2.
Figure 2: SIP Communication between CS and the SIP Server
2.1 Request to Routing Server
INVITE sip:[email protected]:5061;user=phone SIP/2.0
Call-ID: 25769803782-[email protected]
From: <sip:[email protected]:3560;user=phone>;tag=30705
To: <sip:[email protected]:5061;user=phone>
CSeq: 1 INVITE
Via: SIP/2.0/UDP 10.5.30.239:3560;branch=z9hG4bK-600000006-a051eef-7
Contact: sip:54321001; tgrp=67;trunk-
[email protected]:3560;user=phone
Supported: timer,100rel
Max-Forwards: 70
Vz-CallInfo:InTg=67;dn-no=12345001;dn-noa=0;dn-np=0;cpn-
no=54321001;cpn-si=3;cpn-noa=0;cpn-np=0;cpn-
pi=0;cpc=0;jip=12345678;cic-cc=12;cic-ton=1;cic-np=2;ocn-no=1234;ocn-
noa=0;ocn-np=0;bc_xfercaps=8;bc_coding=2;bc_rate=23;bc_xfermode=2;
bc_ulprot=3;bc_layerident=2;bc_ubytes=49 48 32 50 32 50 32
51;globalcallid=0 0 0 25 70 86 192 193 129 32 0 1 0 0 0 15
Content-Length: 0
CS inserts additional call information parameters, if available, in the Vz-CallInfo Header.
2.2 Possible Response Formats
CS supports the following formats of ‘301/302’ response messages.
Format 1 2.2.1
Route SIP Server -> CS (Compliance with RFC 4904)
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SIP/2.0 300 Multiple Choices/302 Moved temporarily
Via: SIP/2.0/UDP 10.5.30.239:3560;branch=z9hG4bK-600000006-a051eef-7
From: <sip:[email protected]:3560;user=phone>;tag=30705
To: <sip:[email protected]:5061;user=phone>;tag=583330932
Call-ID: 25769803782-[email protected]
CSeq: 1 INVITE
Contact: <sip:12345001;tgrp=24;trunk-context=local@10.20.29.64:5061>
Contact: <sip:12345001;tgrp=98;trunk-context=local@10.20.29.64:5061>
Content-Length: 12
Content-Type: application/text
RTID = 10
Format 2 2.2.2
SIP/2.0 300 Multiple Choices/302 Moved Temporarily
Via: SIP/2.0/UDP 10.5.30.239:3560;branch=z9hG4bK-600000006-a051eef-7
From: <sip:[email protected]:3560;user=phone>;tag=30705
To: <sip:[email protected]:5061;user=phone>;tag=583330932
Call-ID: 25769803782-[email protected]
CSeq: 1 INVITE
Contact: <sip:[email protected]:5061>
Content-Length: 28
Content-Type: application/text
TG = 68, 59, 70, 24, 56, 98
RTID = 10
Note:
The RTID field is optional and can be received in SDP content. If it is received, RSG sends the RTID value to SEE, and SEE reports
the RTID value to EC.
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Basic Call Flow 3.
Figure 3: Message Flow
1. Call Ingress in the CS through IP/TDM network.
2. CCE sends Call Info to SEE.
3. SEE dips to PE to find services associated with the Incoming Call.
4. PE executes policies associated with Incoming calls based on the Trunk Group Service Trigger plan.
PE then identifies whether or not there is need for SIP-based SCP Interaction and sends a response
with RSG details back to SEE.
5. SEE applies a DA rule to the called number if applicable and sends Incoming call Info to RSG.
6. RSG sends a SIP INVITE message with Incoming call information to the external SIP Routing Server
Node.
7. The Routing Server sends a ‘300/302’ response with list of IDs. Based on PE Startup Configuration,
these IDs are either mapped to Trunk Group IDs or Route List IDs that the ControlSwitch uses for
routing and re-routing. The optional RTID field is present in the response.
8. RSG passes the ID list and RTID value to SEE.
9. SEE sends the ID list to PE and reports the RTID value to EC..
10. PE initiates post-processing and applies external routes to the Trunk Group or Route List mapping
based on startup configuration. After mapping the IDs, PE prunes the trunk group list based on
Ingress and Egress codec intersection and trunk group/CCE admin status. PE returns the final
Egress trunk group list to SEE.
11. SEE sends the call to the outgoing CCE.
12. CCE sends the call out on the IP/TDM network.
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RSG Call Flow 4.
Figure 4: Call Flow
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CDR Information 5.
CS records the dip events in the CDR. If dip succeeds, the CS receives a ‘300 Multiple Choice’ message
including the trunk group list, and records the following information:
<SVC ID="32" SUCC="1" ServiceNodeId="536" ServiceCategory="
ExternalRoutingService” TapGatewayId="691"> <Time>2010-10-
19+01:23:38.023</Time>
The CS marks the dip as unsuccessful under the following circumstances:
CS receives a 4xx/5xx/6xx message for INVITE
the INVITE request times out
CS cannot reach SCP
For an unsuccessful call, the CS records following information:
<SVC ID="32" SUCC="0" ServiceNodeId="536" ServiceCategory="
ExternalRoutingService " TcapGatewayId="691"><Time> 2010-10-
19+01:23:38.023</Time>
If the RTID field is received in the 3xxx response, its value shall be recorded in the CDR.
<SVC ID="32" SUCC="1" TrunkgroupIds="23,10067,157,123"
ServiceNodeId="102" ServiceCategory="ExternalRoutingService"
RoutingSIPGatewayId="22" RTID="10"></SVC>
5.1 Call Tracing and Routing Dips
When a call that involves routing dips is triggered for tracing, all the required messages can be viewed.
The following messages are traced:
Routing dip request sent by SEE
SIP request sent by RSG
SIP responses or timeouts in the RSG
Routing dip response received by SEE
The RSG sends the following messages/information in the trace messages:
Service Node ID to which the SIP request is being sent
Content of the SIP requests and responses
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Alarms 6.
RSG supports following alarms:
General Life cycle (Startup, Shutdown, and Disable) alarms related to CS element.
CPU overload alarm
Process related alarms: Queue delay
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Configuration 7.
For SIP routing configuration, refer to ControlSwitch Advanced Elements and Services User's Manual,
section SIP Routing Configuration.
7.1 PE Mapping
External Route IDs returned by the External Route Server are either mapped to internal ControlSwitch
trunk group IDs or route list IDs based on the EXTERNAL_ROUTEIDTYPE application parameter.
The EXTERNAL_ROUTEIDTYPE parameter is integer-based, with 1 and 8 as possible values (the default
value is 1). This parameter determines external route mapping: EMS provisions this parameter to PE,
and PE reads the parameter during start-up and configures the external route mapping behavior.
When the value is set to 1, PE uses the external route ID to trunk group ID mapping.
When the value is set to 8, PE uses the external route ID to route list ID mapping.
Any change to the ETERNAL_ROUTEIDTYPE parameter is only reflected following a PE restart.
The application parameter can be changed from the backend (database) by updating the application
parameters table with the following SQL statement:
update application_parameters set parameter_value = <id> where
parameter_name = 'EXTERNAL_ROUTEIDTYPE';
Note:
All the PEs must have a uniform behavior. Restart all PEs after making changes to this application parameter.
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Environment Variables 8.
Export environment variables in the ‘runrsg’ file located in the ‘/opt/IPVRlsg’ directory on the RSG
platform.
For example:
EnvRSG_RFC4904Support =1
export EnvRSG_RFC4904Support
Restart RSG after changing environment variable values:
Name
Supported values
Default Value
Description
EnvRSG_RFC4904Support
0 or 1
0
Includes ‘tgrp=’ (Ingress TG) and ‘trunk-
context=Local’ parameters (RFC 4904) in
contact header of INVITE sent to Remote SIP
Route server.
EnvRSG_SendVzPassThru
Header
0 or 1
0
Pass through of ‘VzPassThrough’ header fields
to External SIP Service Node if received in
ingress INVITE (applicable for SIP Ingress only).
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