Best Practice - Configure Destination Path Resiliency through Independent Internet Connections

Overview

The SBC 1000/2000 and SBC SWe Edge now support two independent Internet connections to a single far end Internet destination, such as the Microsoft 365 (Teams) Phone System. In this deployment type, the SBC 1000/2000 recognizes that the Internet destination is not reachable from a given (preferred) ISP, and all subsequent calls are routed (via backup default route) to the secondary ISP to reach the intended Internet destination.  Upon determining the Internet destination is accessible through the preferred ISP, the user can choose when to revert back to the primary gateway.  In the case where the secondary gateway fails, the switch back to primary gateway is performed automatically.

Destination Path Resiliency 

Step 1: Review Prerequisites/Guidelines

• SBC 1000/2000 Release 9.0.2 or later, or
• SBC SWe Edge Release 11.0 or later 

• Any pair of gateways being monitored will be considered a primary/backup route pair. No other static route should use either of these gateways.
• Only IPv4 will be supported;  IPv6 cannot be configured for link monitoring.
• This feature supports SBC 1000 v2 version, SBC 2000 and SBC SWe Edge.

• It is assumed that management traffic utilizes an interface on a private network.

• This solution requires two Ethernet interfaces to be exclusively assigned for Microsoft Teams Direct Routing Signaling Groups (one for Primary and one for Backup). Other SIP Signaling Groups require additional Ethernet interface(s).

Step 2: Install SBC Edge

These instructions assume the SBC 1000/2000 or SBC SWe Edge is installed and running. If the product is not installed, refer to the links below.

Installation Requirements

Step 3: Configure SBC Edge

For Internet Resiliency (Default Backup Route), the following components need to be configured in theSBC 1000/2000 or SBC SWe Edge.

Access WebUI

1. Access the WebUI.
2. Configure the components detailed below. 

Configure Network Interfaces

Configure Network Interfaces as follows:

1. In the left navigation pane, go to Node Interfaces > Logical Interfaces.

2. Configure two network interfaces connected to ISP A and ISP B. For details on configuring Logical Interfaces, refer to: Configuring and Modifying Logical Interfaces.

   

Default Routes

This step is to create two default routes: primary (primary ISP) and secondary (secondary ISP). The ability to add a secondary route is enabled provided both the primary and backup routes are configured with different metric values. The route with the lowest metric value is the highest priority and will always be considered the primary default route.

Create the default routes as follows:

1. In the left navigation pane, go to Protocols > IP > Static Routes.
2. Create two routes. For details on configuring Default Routes, refer to: Managing Static IP Route Tables.
3. Assign Metric Value of 1 to the Gateway associated with ISP A - Primary.

4. Assign Metric Value of 2 to the Gateway associated with ISP B - Backup.

   
   

Link Monitors

Create three Link Monitor Entries, one for each default gateway and one for the Monitored Host:

1. In the left navigation pane, go to Protocols > Network Monitoring > Link Monitors.

2. Create Link Monitors. For details on configuring Link Monitors, refer to:  Managing Link Monitor Configuration Tables.

   

3. Set the Link Monitor Type to Backup Default Route.

   GW1
   
   
   Host
   
   
   

   Note

   If the peer type is host, the ICMP Echo and Echo Reply is the the protocol used. If the peer is a gateway, the protocol is ARP request/reply.

SIP Server Tables

The solution requires two identically configured SIP Server tables pointing to Microsoft Phone System. One table will be used for Primary and one for Backup connection to Microsoft.

1. In the left navigation pane, go to SIP > SIP Server Tables.

2. Create two identical SIP Server tables pointing to the Microsoft Phone System. For details on configuring SIP Server Tables, refer to: Managing SIP Server Tables.

   

Signaling Groups

Two signaling groups are required to connect the SBC Edge with Microsoft Teams: Microsoft Teams Primary and Microsoft Teams Backup.

Create the two SIP Signaling Groups as follows:

1. In the left navigation pane, go to Signaling Groups.

2. Create two SIP Signaling Groups pointing to the Microsoft Phone System. For details on configuring SIP Signaling Groups, refer to Managing SIP Signaling Groups.

   
3. Associate the Microsoft Teams Primary Signaling Group with the Network Interface connected to ISP A.

4. Associate the Microsoft Teams Backup Signaling Group with the Network Interface connected to ISP B.

   

   Note

   Ensure that no other Signaling Group is associated with Network Interfaces assigned to Microsoft Teams Primary/Backup Signaling Groups.

Call Routing

This step verifies the Call Routing table entry responsible for routing calls to Microsoft Teams is configured with the two destination Signaling Groups (Microsoft Teams Primary and Microsoft Teams Backup).

Verify the Call Routing entries as follows:

1. In the left navigation pane, go to Call Routing.
   

2. Ensure the Call Routing Table entry responsible for routing calls to Microsoft Teams is configured with two Destination Signaling Groups (Teams Primary and Teams Backup). For details on configuring Call Routing Tables, refer to Managing Call Routing Tables.

   

Step 4: Configure Microsoft Teams

The following elements require configuration for Internet Resiliency (Backup Default Route) in the SBC Edge and Microsoft Teams.

Session Border Controllers

The solution requires two Session Border Controllers (SBCs) entries configured on Microsoft Phone System. Use the following specifications for configuration:

SBC1 needs to be associated with the Public IP address assigned to the SBC Edge by ISP A and SBC2 needs to be associated with the Public IP address assigned to the SBC Edge by ISP B.

The two entries cannot share the same SIP signaling port. For example, use port 5061 to configure SBC1 and port 5062 to configure SBC2.

Create SBC on Microsoft Phone System - Port 5061

Create SBC on Microsoft Phone System - Port 5062

Ensure the SIP Signaling Group Listening Ports in the SBC Edge are configured to match the Microsoft Phone System SIP Signaling ports. For details on SIP Signaling Groups, refer to Managing SIP Signaling Groups.

SIP Signaling Group Listening Ports

Voice Route

Ensure that both SBC1 and SBC2 are enrolled in the Microsoft Teams voice route that is used to reach the SBC Edge.

Verify Voice Route

Step 5: Verify System Failover for Internet Resiliency

Use the following procedure to verify the Internet Resiliency (Default Backup Route) configuration has been successfully created.

1. Ensure that both Primary and Backup network connection paths are available via Link Monitor Table (under Service Status). For how to view the Link Monitor table, refer to Managing Link Monitor Configuration Tables.
2. Verify that outgoing and incoming calls are working as follows:
1. Make a call from the SIP Client to a Microsoft Teams user.
2. Verify voice transmission in both directions.
3. Disconnect the call. Ensure the connection is terminated on both clients
4. Repeat the steps in reverse direction – Microsoft Teams user to the SIP Client.
3. Terminate the Primary network connection by disabling the network interface or unplugging the network cable.
4. Allow the system to fail over to Backup Connection.
5. Verify that both outgoing and incoming calls are working. Refer to step 2.
6. Restore network connectivity on the primary path.

7. Perform manual system switch back to Primary Gateway (from the Link Monitor table, click Switch Back to Primary Gateway).

   Note

   For detailed instructions on using the Switch Back to Primary Gateway option, refer to Creating and Modifying Link Monitor Configuration Table Entries.

8. Verify that both outgoing and incoming calls are working. Refer to Step 2.

Step 6: Switch Back to Primary Gateway - What to Expect Next

For a Failover to the Default Backup Gateway, the system automatically reconfigures the Default Gateway from the Primary to the Backup whenever the network failure on the Primary Link is detected. The gateway change triggers the Primary Microsoft Teams Signaling Group to go Down and the backup Microsoft Teams Signaling Group to became Active.

Manual Switch Back to Primary Signaling Group

The system will not make any automatic network configuration changes when the Primary Microsoft Teams Signaling Group Link is restored. The backup Microsoft Team Signaling Group will continue to be used until the Gateway change is manually initiated or the secondary route also fails. Initiate the Gateway change from the Web UI as follows:

1. Access Protocols > Network Monitoring > Link Monitors.
2. Click Switch Back To Primary Gateway.