The echo-passive command enables the passive Echo function of BFD.
The undo echo-passive command disables the passive Echo function of BFD.
| Parameter | Description | Value |
|---|---|---|
| all | Enables the passive echo function of all BFD sessions. | - |
| acl basic-acl-number | Enables the passive echo function of the BFD session by specifying an ACL. | It must be a created basic ACL ranging from 2000 to 2999. |
By default, the passive Echo function of BFD is disabled.
Enable global BFD before enabling the passive echo function of BFD.
The BFD echo packet is looped back through ICMP redirect at the remote end. In the IP packet that encapsulates the BFD echo packet, the destination address and the source address are the IP address of the outgoing interface of the local end. Therefore, in the ACL rule, both the source addresses of the remote end and the local end must be permitted.
# Enable the passive echo function for the BFD session that matches ACL 2000 (the local address is 10.1.1.1 and the remote address is 10.1.1.2).
<sysname> system-view [sysname] acl 2000 [sysname-acl-basic-2000] rule permit source 10.1.1.1 0 [sysname-acl-basic-2000] rule permit source 10.1.1.2 0 [sysname-acl-basic-2000] quit [sysname] bfd [sysname-bfd] echo-passive acl 2000