SIP FQDN Support

The Fully Qualified Domain Name (FQDN) feature supports entering a Fully Qualified Domain Name instead of an IP Address into the c= line of the SDP on the outgoing leg. If the outgoing Fully Qualified Domain Name (FQDN) is configured and enabled in the SIP Profile pane, the SIP Signaling and/or VoIP module IP addresses will be replaced with the FQDN in the outgoing request and/or outgoing SIP response. Follow the procedure below to configure FQDN on IMG 2020. 

Call Flows

Outgoing with FQDN Enabled

The call flow below displays an SS7 to SIP call flow where FQDN's is enabled.

Open

Incoming FQDN DNS Query

The call flow below displays the case where an incoming INVITE includes a c= line with a FQDN in place of an IP Address. In this case, a DNS query is executed before the call is established.

Open

Configuration Procedures

Incoming support is always enabled and can not be modified. If the IMG 2020 receives an incoming INVITE with a Fully Qualified Domain Name (FQDN) in the SIP URI, a DNS query will be initiated. On the outgoing side, the Fully Qualified Domain Name must be configured for the feature to initiate a DNS query. See configuration below.

Initial Configuration

The procedure below explains how to configure the IMG 2020 to execute a DNS Query on the outbound leg. Before configuring the outbound FQDN feature, the IMG 2020 must have an initial configuration created on it. Follow the Basic Configurations procedure before proceeding.

Create a DNS Server and DNS Client

Create a DNS Server and DNS Client object. See Below.

• Right click on the Dialogic object and select New External Network Elements. Refer to the External Network Elements topic for more information on configuring this object.

• Right click on the External Network Elements object and select New DNS Servers. Refer to the DNS Servers topic for more information on configuring this object.

• Right click on the DNS Servers object and select New DNS Server. Enter IP Address of this DNS server. Refer to the DNS Server topic for more information on configuring the remaining fields in this object.

• Right click on the IMG 2020 physical node object and select New DNS Client. The IP address will default to the IP address of the Control Port. Select from drop down menu in the Primary DNS Server field the DNS Server just created. Refer to the DNS Client topic for more information on configuring the remaining fields in this object.

Create SIP Profile (SGP)

• Create a SIP Profile. Right click on the Dialogic object and select New Profiles. The Profiles object is a parent or container object and no configuration is needed here.

• Right click on the Profiles object and select New SIP Profile. The first profile that gets created is a Default SIP Profile and cannot be modified. Disregard this profile.

• Right click on the Profiles object just created again and select New SIP Profile. Either enter a Name into the name field that identifies this profile or accept the default entry. In this procedure the name entered was GW_FQDN_Profile

• Right click on the SIP Profile object just created and select New SIP Advanced Settings. Click on the Outgoing FQDN field and select when the Fully Qualified Domain Name servers will be displayed from drop down menu. Refer to the screen capture below.

Create Remote Gateway

Create a Remote Gateway that will be communicating with the Outgoing Channel Group. The gateway being configured  will need the SIP Profile with the FQDN configured in it. To link the SIP profile created with a remote SIP gateway, an external network element must also be created. The next few sections describe how to configure this.

• Right click on the Dialogic object and select New External Network Elements. The External Network Elements object is a container object and no configuration is needed in this object. Refer to External Network Elements for more information.

• Right click on External Network Elements object and select New External Gateways. The External Gateways object is also a container object. Under the External Gateways object, multiple individual gateways can be created. Refer to External Gateways topic for more information.

• Right click on External Gateways and select New External Gateway. Refer to the screen capture and table below.

Configure SIP Signaling

The configuration above displays how to configure the SIP Profile and External SIP Gateway so that the FQDN Support feature is configured. The next step is to configure the SIP signaling stack and SIP Channel Groups. Refer to the Configure SIP (Single SIP IP) topic for a procedure on how to configure the SIP functionality. When referencing the Configure SIP topic, the procedure describes the steps required to configure the SIP stack and associated objects. The procedure does not describe certain settings that are pertinent to the FQDN Support feature. Below is short procedure and a screen capture of what needs to be configured in the SIP Signaling object for this feature.

Configure SIP IP Address Object for FQDN

• Right click on the IMG 2020 physical node object and select New Signaling. The Signaling topic is a parent or container object and no configuration is needed here. Refer to the Signaling topic for more information.

• Right click on the Signaling object just created and select New SIP. Refer to the SIP Signaling topic for information on how to configure this object.

• Right click on the SIP Signaling object and select New SIP IP Address. Enter a FQDN in the Fully Qualified Domain Name (FQDN) field. Refer to the screen capture below.

 Optional: SIP Virtual Address

When configuring a SIP Virtual Address that will be utilizing the Fully Qualified Domain Name feature, the Network Interface Object created for the SIP Virtual Address must have the Gratuitous ARP and ARP Responses field set to Disable. Below is procedure describing what would need to be configured if a SIP Virtual Address was being configured with a Fully Qualified Domain Name server.

Create a Network Interface for SIP Virtual Address Feature

The procedure below describes what needs to be configured if the FQDN Support feature utilizes a SIP Virtual Address. In this scenario, the SIP signaling stack must be configured to Single IP Mode. Within the SIP Signaling object, the IP Operation Mode field must be set to Single IP. Refer to the IMG 1010 - SIP Signaling Object topic for information on this.

• Right click on IP Network object and select IP Address. In the Source Endpoint field select Services from the drop down menu. Enter an IP Address for this interface and enter the Default Gateway IP address.

• Click In the Gratuitous ARP and ARP Responses field select Disable from the drop down menu.

• In the Fully Qualified Domain Name field enter the FQDN. Refer to IP Address topic for more information on configuring the remaining fields in this object.

Create SIP Stack

• Right click on the physical node object and select New Signaling. The Signaling object is a parent or container object and no configuration is needed here. Refer to the topic for more information on this object.

  • Right click on the Signaling object and select New SIP. Verify that the IP Operation Mode field is set to Single IP. Refer to the IMG 1010 - SIP Signaling Object topic for information on configuring each of the remaining fields in this object.

 Create the SIP Virtual Address Object

• Right click on the SIP Signaling object created earlier and select New SIP Virtual Address. The SIP Virtual IP Address field will be automatically populated with the address of the interface that has the Gratuitous ARP and ARP Responses field set to Disable. Refer to screen capture below.

• The SIP Virtual Address will now use the Fully Qualified Domain Name instead of the IP address on outgoing messaging.

Configure SIP Signaling

The configuration above displays how to configure the SIP Profile, External SIP Gateway, and SIP Virtual Address so that the SIP FQDN Support feature is configured. The next step is to configure the SIP Channel Groups. Refer to the Configure SIP (Single SIP IP) topic for a procedure on how to configure the SIP functionality.

Troubleshooting

FQDN Enabled but No FQDN Configured

If the outgoing FQDN options are enabled but no FQDN hostname is entered then the IMG 2020 will transmit a WARNING!! and process the call normally with IP addresses. Below is the warning displayed and some scenarios that would generate this warning.

• If the Signaling ONLY option is enabled but the Signaling doesn't have an FQDN entry, the IP address of the local IMG 2020 will be sent.

• If the SDP C Equal Line ONLY option is enabled but the CPU interface doesn't have the FQDN entry, the IP address of the local CPU interface will be sent.

• Both options are enabled. The SIP Signaling object doesn't have an FQDN entry but the CPU interface object does. The IP address of the local IMG 2020 will be sent. The FQDN of the CPU interface will be displayed in the SDP c=line.

• Both options are enabled. The SIP Signaling has an FQDN entry but the CPU interface does not. The FQDN of the local IMG 2020 will be sent. The IP address of the CPU interface will be displayed in the SDP c=line.

Call Trace - FQDN Failure Message

If DNS is not configured or not configured properly, the call will fail responding with a 488 "Not Acceptable Here". Click on the following link for a call trace of the failure message. Call Trace Failure Message

RADIUS

VSA's

The following VSAs support the Fully Qualified Domain Name feature.

• dialogic-voip-src-sig-fqdn

• dialogic-voip-src-rtp-fqdn

• dialogic-voip-dst-rtp-fqdn

Refer to the RADIUS - Dialogic VSA's topic for more information.

Dictionary File

The radius dictionary file supports the FQDN feature. On a Linux server running freeRADIUS, this file should be copied into /usr/share/freeradius directory.

Example INVITE Messages

Outgoing FQDN Option = Signaling ONLY

When the Outgoing FQDN option is set to Signaling Only, the FQDN of the local IMG 2020 signaling IP address is inserted in the outgoing SIP messages.

Outgoing FQDN Option = SDP C Equal Line ONLY

When the Outgoing FQDN option is set to SDP c=line ONLY, the FQDN of the local IMG 2020 CPU address is inserted in the outgoing SIP messages.

Outgoing FQDN Option = Both

The following shows a SIP INVITE message when the Outgoing FQDN option is set to Both.