Summary
This describes the SG Signaling/Media Source IP and NAT Traversal configuration.
When an INVITE is sent from the SBC to a SIP destination:
- The call route specifies the egress SG.
- If the SG Signaling/Media Source IP is set to Auto, the egress Ethernet is selected by the best match in the IP Routing Table.
- If the SG Signaling/Media Source is set to a specific Ethernet/IP interface, the INVITE is forwarded out that specified port; however, the IP Route Table must have an IP Route to the destination network. Even when a specific port is selected, the IP Routing engine must still be able to route the packet towards the destination IP network.
The Signaling/Media IP Source configuration overrides the IP Routing Table for selecting a particular egress Ethernet interface. Regardless, the IP Route Table must contain the appropriate routing entries for the SBC to send the packet towards the destination IP network.
Below is a configuration example for Signaling/Media Source IP set to Auto.
In a call from the phone to SIP Server 10.3.1.253:
- The call route specifies the Network 1 SG Destination Signaling Group.
- The Network 1 SG Signaling Group specifies that calls be sent to the destination server configured in the Network 1 SIP Servers Table.
- The Network 1 SIP Server Table specifies the SIP Server IP 10.3.1.253.
- With the Network SG 1's Signaling/Media Source IP configured to Auto, the IP Route Table is consulted and the Ethernet 1 IP (Next Hop) is selected because 10.3.1.0/24 is the best matching route.
- The INVITE is sent out Ethernet 1 to the SIP Server.
Below is a configuration example for Signaling/Media set to Specific Ethernet/IP interface.
In a call from the phone to SIP Server 50.2.2.201:
- The call route specifies the Network 2 SG Destination Signaling Group.
- The Network 2 SG Signaling Group specifies that calls be sent to the destination server configured in the Network 2 SIP Servers Table.
- The Network 2 SIP Server Table specifies the SIP Server IP 50.2.2.201.
- With the Network SG 2's Signaling/Media Source IP configured to Ethernet 2 IP (50.2.2.1) , the INVITE confined to egress on Ethernet Port 2.
- IP Routing Table is consulted to ensure there is an IP route to the 50.2.2.0/24 network.
- The INVITE is sent out Ethernet 2 to the SIP Server.
In a call from the phone to SIP Server 50.3.3.153:
- The call route specifies the Network 2 SG Destination Signaling Group.
- The Network 2 SG Signaling Group specifies that calls be sent to the destination server configured in the Network 2 SIP Servers Table.
- The Network 2 SIP Server Table specifies the SIP Server IP 50.3.3.153.
- With the Network SG 2's Signaling/Media Source IP configured to Ethernet 2 IP (50.2.2.1) , the INVITE confined to egress on Ethernet Port 2.
- IP Routing Table is consulted to ensure there is an IP route to the 50.3.3.0/24 network.
- The INVITE is not sent as there is no IP Route to the 50.3.3.0/24 network.
Below is a configuration example for a SIP Server on a different interface than the one set in the SG Signaling/Media configuration.
In a call from the phone to SIP Server 10.3.1.253:
- The call route specifies the Network 2 SG Destination Signaling Group.
- The Network 2 SG Signaling Group specifies that calls be sent to the destination server configured in the Network 2 SIP Servers Table.
- The Network 2 SIP Server Table specifies the SIP Server IP 10.3.1.253.
- With the Network SG 2's Signaling/Media Source IP configured to Ethernet 2 IP (50.2.2.1) , the INVITE confined to egress on Ethernet Port 2.
- IP Routing Table is consulted to ensure there is an IP route to the 10.3.1.0/24 network. The IP Route table specifies the 10.3.1.253 SIP Server is on Ethernet/IP port 1.
- The INVITE is not transmitted because the Signaling/Media IP is configured for Ethernet 2 IP (50.2.2.1) while the destination SIP Server is on Ethernet/IP port 1.
Setting a NAT Public IP Address
Below is a configuration example for a NAT Public IP.
In a call from the phone to SIP Server 50.2.2.201:
- The call route specifies the Network 2 SG Destination Signaling Group.
- The Network 2 SG Signaling Group specifies that calls be sent to the destination server configured in the Network 2 SIP Servers Table.
- The Network 2 SIP Server Table specifies the SIP Server IP 50.2.2.201.
- With the Network SG 2's Signaling/Media Source IP configured to Auto , the IP Routing Table is consulted to ensure there is an IP route to the 50.2.2.0/24 network.
- The INVITE is sent out Ethernet 3 to the SIP Server with the Source IP address of SBC's Ethernet/IP port 3.
- The SIP and SDP IP addresses are set to 50.4.4.155 because NAT Public IP is configured in the egress Signaling Group.