Contents

GRE commands· 1

gre checksum·· 1

gre key· 1

keepalive· 2

service-class· 3

GRE commands

gre checksum

Use gre checksum to enable GRE checksum.

Use undo gre checksum to disable GRE checksum.

Syntax

gre checksum

undo gre checksum

Default

GRE checksum is disabled.

Views

Tunnel interface view

Predefined user roles

network-admin

Usage guidelines

GRE checksum verifies packet integrity.

You can enable or disable GRE checksum at each end of a tunnel as needed. After GRE checksum is enabled, the sender does the following:

·     Calculates the checksum for the GRE header and the payload.

·     Sends the packet containing the checksum information to the peer.

The receiver calculates the checksum for the received packet and compares it with that carried in the packet. If the checksums are the same, the receiver processes the packet. If the checksums are different, the receiver discards the packet.

If a packet carries a GRE checksum, the receiver checks the checksum whether or not the receiver is enabled with GRE checksum.

Examples

# Enable GRE checksum.

<Sysname> system-view

[Sysname] interface tunnel 2 mode gre

[Sysname-Tunnel2] gre checksum

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

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 and 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 keepalive is enabled.

GRE/IPv6 mode tunnel interfaces do not support this command.

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

 

service-class

Use service-class to specify a service class value for a GRE tunnel interface.

Use undo service-class to restore the default.

Syntax

service-class service-class-value

undo service-class

Default

No service class value is specified for a GRE tunnel interface.

Views

Tunnel interface view

Predefined user roles

network-admin

Parameters

service-class-value: Specifies a service class value. The lower the service class value, the lower the forwarding priority for a tunnel. If no service class value is specified for a tunnel, the tunnel is considered to have the lowest forwarding priority.

Usage guidelines

Use this command only on a GRE tunnel interface.

The device selects a tunnel to forward a packet in the following order:

1.     The tunnel that has the same service class value as the packet.

2.     If multiple tunnels have the same service class value as the packet, the device randomly selects one of the tunnels to forward the packet.

3.     If no tunnel has the same service class value as the packet, the device randomly selects a tunnel from all tunnels that have the lowest forwarding priority.

To set a service class value for packets, use the remark service-class command in traffic behavior view. For information about the remark service-class command, see QoS commands in QoS Command Reference.

Examples

# Set the service class value of Tunnel 0 to 5.

<Sysname> system-view

[Sysname] interface tunnel 0 mode gre

[Sysname-Tunnel0] service-class 5