Contents

GRE commands· 1

gre key· 1

keepalive· 1

GRE commands

gre key

Use gre key to configure a key for a GRE tunnel interface.

Use undo gre key to restore the default.

Syntax

gre key key

undo gre key

Default

No key is configured for a GRE tunnel interface.

Views

Tunnel interface view

Predefined user roles

network-admin

Parameters

key: Specifies the key for the GRE tunnel interface, in the range of 0 to 4294967295.

Usage guidelines

You can configure a GRE key to check for the validity of packets received on a GRE tunnel interface.

When a GRE key is configured, the sender puts the GRE key into each sent packet. The receiver compares the GRE key in the received packet with its own GRE key. If the two keys are the same, the receiver accepts the packet. If the two keys are different, the receiver drops the packet.

Both ends of a GRE tunnel must have the same key or no key.

Examples

# Configure the GRE key as 123 for the GRE tunnel interface Tunnel 2.

<Sysname> system-view

[Sysname] interface tunnel 2 mode gre

[Sysname-Tunnel2] gre key 123

keepalive

Use keepalive to enable GRE keepalive, set the keepalive interval and the keepalive number, and configure the keepalive mode.

Use undo keepalive to disable GRE keepalive.

Syntax

keepalive [ interval [ times ] | reply-check-only ]*

undo keepalive

Default

GRE keepalive is disabled.

Views

Tunnel interface view

Predefined user roles

network-admin

Parameters

interval: Specifies the keepalive interval, in the range of 1 to 32767 seconds. The default value is 10.

times: Specifies the keepalive number, in the range of 1 to 255. The default value is 3.

reply-check-only: Enables the reply-check-only keepalive mode. In this mode, the device places the tunnel interface state to up only when it receives a keepalive acknowledgment packet replied from the peer. The reply-check-only mode is disabled by default. If you do not specify this keyword, the device places the tunnel interface state to up when it receives a keepalive packet initiated or replied from the peer.

Usage guidelines

This command enables the tunnel interface to send keepalive packets at the specified interval. If the device receives no response from the peer within the timeout time, it shuts down the local tunnel interface. The device brings the local tunnel interface up if it receives a keepalive acknowledgment packet from the peer. The timeout time is the result of multiplying the keepalive interval by the keepalive number.

Enable the reply-check-only mode in scenarios where the local device can receive keepalive packets from the peer but cannot send keepalive packets, such as remote-to-local one-way communication of a tunnel. In such a scenario, the peer shuts down the tunnel interface because it cannot receive keepalive packets from the local device. The local device, however, brings up the tunnel interface mistakenly when it receives a keepalive probe packet initiatively sent from the peer. After the reply-check-only mode is enabled, the local device brings up the tunnel interface only when it receives a keepalive probe reply from the peer. It keeps the tunnel interface down when it receives keepalive probe packets from the peer, so as to avoid setting wrong tunnel interface state.

The device always acknowledges the keepalive packets it receives whether or not GRE keepalive is enabled.

Examples

# Enable GRE keepalive, set the keepalive interval to 20 seconds, and set the keepalive number to 5.

<Sysname> system-view

[Sysname] interface tunnel 2 mode gre

[Sysname-Tunnel2] keepalive 20 5