HA Features
HA nodes support configuration checkpointing, which you are required to set up so that the configurations across the HA node are synchronized. In addition, you can set up the following optional HA node features:
- Multiple rear interface support
- Gateway link failure detection and polling
Multiple Rear Interfaces
Configuring your HA node to support multiple rear interfaces eliminates the possibility that either of the rear interfaces you configure for HA support will become a single point of failure. Using this feature, you can configure individual Oracle® Enterprise Session Border Controller s with multiple destinations on the two rear interfaces, creating an added layer of failover support.
When you configure your HA node for multiple rear interface support, you can use last two rear interfaces (wancom1 and wancom2) for HA—the first (wancom0) being used for Oracle® Enterprise Session Border Controller management. You can connect your Oracle® Enterprise Session Border Controller s using any combination of wancom1 and wancom2 on both systems. Over these rear interfaces, the Oracle® Enterprise Session Border Controller s in the HA node share the following information:
- Health
- Media flow
- Signaling
- Configuration
For example, if one of the rear interface cables is disconnected or if the interface connection fails for some other reason, all health, media flow, signaling, and configuration information can be checkpointed over the other interface.
Health information is checkpointed across all configured interfaces. However, media flow, signaling, and configuration information is checkpointed across one interface at a time, as determined by the Oracle® Enterprise Session Border Controller ’s system HA processes.
Configuration Checkpointing
During configuration checkpointing, all configuration activity and changes on one Oracle® Enterprise Session Border Controller are automatically mirrored on the other. Checkpointed transactions include adding, deleting, or modifying a configuration on the active Oracle® Enterprise Session Border Controller . This means that you only need to perform configuration tasks on the active Oracle® Enterprise Session Border Controller because the standby system will go through the checkpointing process and synchronize its configuration to reflect activity and changes.
Because of the way configuration checkpointing works, the ACLI save-config and activate-config commands can only be used on the active Oracle® Enterprise Session Border Controller .
- When you use the ACLI save-config command on the active Oracle® Enterprise Session Border Controller , the standby Oracle® Enterprise Session Border Controller learns of the action and updates its own configuration. Then the standby Oracle® Enterprise Session Border Controller saves the configuration automatically.
- When you use the ACLI activate-config command on the active Oracle® Enterprise Session Border Controller , the standby Oracle® Enterprise Session Border Controller learns of the action and activates its own, updated configuration.
The ACLI acquire-config command is used to copy configuration information from one Oracle® Enterprise Session Border Controller to another.
Gateway Link Failure Detection and Polling
In an HA node, the Oracle® Enterprise Session Border Controllers can poll for and detect media interface links to the gateways as they monitor ARP connectivity. The front gateway is assigned in the network interface configuration, and is where packets are forwarded out of the originator’s LAN.
The Oracle® Enterprise Session Border Controller monitors connectivity using ARP messages that it exchanges with the gateway. The Oracle® Enterprise Session Border Controller sends regular ARP messages to the gateway in order to show that it is still in service; this is referred to as a heartbeat message. If the Oracle® Enterprise Session Border Controller deems the gateway unreachable for any of the reasons discussed in this section, a network-level alarm is generated and an amount you configure for this fault is subtracted from the system’s health score.
The Oracle® Enterprise Session Border Controller generates a gateway unreachable network-level alarm if the Oracle® Enterprise Session Border Controller has not received a message from the media interface gateway within the time you configure for a heartbeat timeout. In this case, The Oracle® Enterprise Session Border Controller will send out ARP requests and wait for a reply. If no reply is received after resending the set number of ARP requests, the alarm remains until you clear it. The health score also stays at its reduced amount until you clear the alarm.
When valid ARP requests are once again received, the alarm is cleared and system health scores are increased the appropriate amount.
You can configure media interface detection and polling either on a global basis in the SD HA nodes/redundancy configuration or on individual basis for each network interface in the network interface configuration.
Note:
To improve the detection of link failures, the switchport connected to the NIU should have Spanning Tree disabled. Enabling Spanning Tree stops the switchport from forwarding frames for several seconds after a reset. This prevents the NIU from reaching the gateway and generates a "gateway unreachable" network-level alarm.
