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.