Configuring Passive BFD Echo
This section describes how to configure passive BFD echo to implement interworking between devices that support the echo function. Passive BFD echo applies only to single-hop BFD sessions.
Usage Scenario
BFD provides the asynchronous detection mode. An auxiliary function of the asynchronous mode is the echo function, which must work with the asynchronous mode. When the echo function is activated, the local system sends a BFD control packet and the remote system loops back the packet through the forwarding channel. If several consecutive echo packets are not received, the session is declared to be Down.
If a device that supports the echo function is deployed on a network, you can enable passive BFD echo for interworking with other vendors' devices.
Pre-configuration Tasks
Before configuring passive BFD echo, complete the following tasks:
Enable BFD globally.
- (Optional) Create an ACL.
Procedure
- Run system-view
The system view is displayed.
- (Optional) Run acl { name basic-acl-name { basic | [ basic ] number basic-acl-number } | [ number ] basic-acl-number } [ match-order { config | auto } ]
The basic ACL view is displayed.
- (Optional) Run rule [ rule-id ] [ name rule-name ] { deny | permit } [ fragment-type { fragment | non-fragment | non-subseq | fragment-subseq | fragment-spe-first } | source { source-ip-address { source-wildcard | 0 | src-netmask } | any } | time-range time-name | vpn-instance vpn-instance-name ] *
An ACL rule is created.
- (Optional) Run quit
Return to the system view.
- Run bfd
The BFD view is displayed.
- Run echo-passive { all | acl basic-acl-number }
Passive BFD echo is enabled.
- To enable passive echo for all BFD sessions, specify the all parameter.
- To enable passive echo for BFD sessions that match a configured ACL rule, specify the acl parameter. You can enable passive echo for BFD control packets that match the permit action and disable passive echo for BFD control packets that match the deny action or do not match any ACL rules.
If an ACL rule is created or modified after a BFD session goes Up through negotiations, this ACL rule can take effect only after the BFD session goes Down and then Up or the parameters of the BFD session are modified.
- Run commit
The configuration is committed.