Administration of the Avaya G350 Media Gateway - Avaya Support

Configuring GRE tunnelingOptional GRE tunnel featuresYou can configure the following optional features in GRE tunnels:●●keepalivekeepalive — enables periodic checking to determine if the tunnel is up or down.Dynamic MTU discovery — determines and updates the lowest MTU on the current routethrough the tunnel.The tunnel keepalive feature sends keepalive packets through the tunnel interface to determinewhether the tunnel is up or down. This feature enables the tunnel’s source interface to informthe host if the tunnel is down. When the tunnel keepalive feature is not active, if the tunnel isdown, the tunnel’s local endpoint continues to attempt to send packets over the tunnel withoutinforming the host that the packets are failing to reach their destination.Use the keepalive command in the context of the GRE tunnel interface to enable the tunnelkeepalive feature. Use the no form of this command to deactivate the feature.The keepalive command includes the following parameters:●seconds — the length, in seconds, of the interval at which the source interface sendskeepalive packets. The default value is 10.● retries — the number of retries after which the source interface declares that thetunnel is down. The default value is 3.The following example configures Tunnel 1 to send keepalive packets every 20 seconds. If thetunnel’s destination interface fails to respond to three consecutive packets, the tunnel’s sourceinterface concludes that the tunnel is down. The source interface continues to send keepalivepackets, but until it receives a response from the tunnel’s destination interface, the tunnelinforms hosts that send packets to the tunnel that the tunnel is down.G350-001# interface Tunnel 1G350-001(if:Tunnel 1)# tunnel keepalive 20 3Done!Note:Note:You do not have to configure tunnel keepalive on both sides of the tunnel.Issue 3 January 2005 171