bfd one-arm-echo

Function

The bfd one-arm-echo command configures the BFD echo function.

The undo bfd command deletes a specified BFD session and cancels the binding.

By default, the BFD echo function is not configured.

Format

bfd session-name bind peer-ip peer-ip [ vpn-instance vpn-instance-name ] interface interface-type interface-number [ source-ip ip-address ] one-arm-echo

undo bfd session-name

Parameters

Parameter	Description	Value
session-name	Specifies the name of a BFD session supporting the BFD echo function.	The value is a string of 1 to 15 case-insensitive characters without spaces. NOTE: When quotation marks are used around the string, spaces are allowed in the string.
peer-ip peer-ip	Specifies the peer IP address bound to the BFD session.	The value is in dotted decimal notation.
vpn-instance vpn-instance-name	Specifies the name of a Virtual Private Network (VPN) instance that is bound to a BFD session.	The value must be an existing VPN instance name.
interface-type interface-number	Specifies the type and number of the interface bound to a BFD session. interface-type specifies the interface type. interface-number specifies the interface number.	-
source-ip ip-address	Indicates the source IP address carried in BFD packets. This parameter is mandatory.	-
one-arm-echo	Indicates a BFD session supporting the BFD echo function.	-

Views

System view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

Among two directly connected devices, one device supports BFD, whereas the other device does not support BFD. To rapidly detect forwarding failures between the two devices, configure a BFD session supporting the BFD echo function on the BFD-supporting device. The BFD-supporting device sends an Echo Request packet to the remote device. The remote device sends the Echo Request packet back along the same path to detect the forwarding link connectivity.

When you configure a BFD session supporting the BFD echo function:

Specify source-ip ip-address. Ensure that the source IP address is correct. The system only checks whether the source IP address is valid (for example, it cannot be a multicast or broadcast address) without checking correctness. When URPF is enabled, ensure that source-ip ip-address can be pinged from the remote device so that the URPF-enabled device does not incorrectly discard BFD packets.
On a network, some devices discard packets with the same source and destination IP addresses, so you are advised to set the value of source-ip ip-address to be different from the IP address of the outbound interface.
If a VPN instance is specified, BFD is configured to detect the one-hop link in the VPN instance.

Prerequisites

Global BFD has been enabled using the bfd command in the system view.

Precautions

The difference between a BFD session supporting the BFD echo function and a common BFD session is as follows:

When configuring a BFD session supporting the BFD echo function, you can only specify local discr-value in the discriminator command.
You can only run the min-echo-rx-interval command to change the interval for receiving BFD packets.

If the IP address of an outbound interface is changed after a BFD session is configured, the source IP address of BFD packets is not updated.
The BFD echo function is only applicable to single-hop BFD sessions.
After the bfd one-arm-echo command is executed, run the commit command to commit the configuration to make the configuration take effect.

Example

# Configure a BFD session test supporting the BFD echo function.

<HUAWEI> system-view
[HUAWEI] bfd test bind peer-ip 10.10.10.1 interface vlanif 100 source-ip 10.10.10.2 one-arm-echo
[HUAWEI-bfd-session-test] discriminator local 100
[HUAWEI-bfd-session-test] commit