bfd bind pw interface

Function

The bfd bind pw interface command binds a BFD session to a PW, so that BFD can detect the connectivity of the PW.

By default, BFD is not configured to detect PW connectivity.

Format

bfd session-name bind pw interface { interface-name1 | interface-type1 interface-number1 } [ remote-peer remote-peer-address pw-ttl { auto-calculate | ttl-number } ] [ track-interface [ interface { interface-name2 | interface-type2 interface-number2 } ] ] [ secondary ]

Parameters

Parameter	Description	Value
session-name	Specifies the name of a BFD session.	The value is a string of 1 to 64 characters, spaces not supported. When quotation marks are used around the string, spaces are allowed in the string. When the name of a BFD session is configured, the uppercase and lowercase letters in the name must be the same as what you enter. BFD session names are case-insensitive. For example, ABC and abc are regarded as the same BFD session. If you have configured ABC as the name of a BFD session, the ABC BFD session view is directly displayed when you configure abc.
interface	Specifies the interface tracked by the BFD session.	The value is a character string: If the BFD session monitors the service PW, the value is interface. If the BFD session monitors the management PW, the value is controller.
interface interface-name1	Specifies the outbound interface of the PW to be detected by the BFD session, that is, the AC interface where the PW resides. In the management PW scenario, the interface is a loopback interface.	-
interface interface-type1 interface-number1	Specifies the outbound interface of the PW to be detected by the BFD session, that is, the AC interface where the PW resides. In the management PW scenario, the interface is a loopback interface.	-
remote-peer remote-peer-address	Specifies the IP address used as the destination address of the PW to be detected by the BFD session, which is usually an LSR ID.	The value is in dotted decimal notation. It cannot be in the format of 127.X.X.X.
pw-ttl	Indicates that the BFD session detects a PW in TTL mode. In this mode, the TTL value can be manually set or automatically calculated.	-
auto-calculate	Indicates that the number of hops along a PW is counted automatically.	-
ttl-number	Specifies the number of hops along the PW to be detected.	The value is an integer ranging from 1 to 255.
track-interface	Specifies the interface tracked by the BFD session when detecting the PW: If the BFD session monitors the service PW and the AC interface goes Down, the BFD session enters the Down state. If the BFD session monitors the management PW, you can associate the BFD session with a specified interface. When the specified interface goes Down, the BFD session enters the Down state.	-
interface-name2	Specifies the interface name tracked by the BFD session.	-
interface-type2	Specifies the interface type tracked by the BFD session.	-
interface-number2	Specifies the interface number tracked by the BFD session.	-
secondary	Configures BFD to detect the connectivity of a secondary PW.	-
select-board slot-id	Specifies the slot ID of an interface board on which a BFD session is established.	-

Views

System view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
bfd	write

Usage Guidelines

Usage Scenario

If PEs on a Multiprotocol Label Switching (MPLS) Layer 2 virtual private network (L2VPN) communicate over PWs, you can enhance service protection by configuring BFD to speed up link fault detection and rapidly trigger upper-layer application switching.

The bfd bind pw command is used to detect the connectivity of SS-PWs and MS-PWs.

If you do not specify remote-peer remoteip-value pw-ttl in the bfd bind pw command, you must run the control-word command to enable the control word for the detected PW.
If you specify remote-peer remoteip-value pw-ttl:
If you choose to specify auto-calculate, the system automatically calculates the number of segments of the detected PW based on remote-peer remoteip-value.
If you choose to specify ttl-value, the number of segments in the detected PW is configured.
If BFD detects changes in the VC encapsulation type of a VPWS PW, indicating the deletion of the Virtual Leased Line (VLL) PW, BFD module deletes the session detecting the VLL PW.
When a large number of service PWs originated from the same source and destined for the same device are available, a large number of BFD sessions are required, which consumes lots of resources. To reduce the consumption of public network link bandwidths and system resources, configure an mPW that has the same source and destination as the service PWs and bind the service PWs to the mPW. This configuration allows the service PWs to track the mPW status. Therefore, a BFD session can be configured only for the mPW to detect faults. The mPW then notifies all service PWs bound to it of the status. This allows the BFD session to also monitor the service PWs.
If a PW is a VPLS SS-PW, you can run the bfd bind pw vsi command to detect PW connectivity. In the bfd bind pw vsi command, the peer peerip-value parameter specifies a PW on a VPLS network. The bfd bind pw vsi command applies only to BFD for PW in TTL mode:
If BFD detects an E2E VPLS SS-PW, the values of peer peerip-value and remote-peer remoteip-value are the same. In this case, you only need to use the bfd sessname-value bind pw vsi vsi-name peer peerip-value command. The TTL is fixed at 255.
If BFD detects an MS-PW in a VPWS accessing VPLS scenario, you must specify both peer peerip-value and remote-peer remoteip-value in the bfd bind pw command.
If you choose to specify auto-calculate, the system automatically calculates the number of segments of the detected PW based on remote-peer remoteip-value.
If you choose to specify ttl, the number of segments in the detected PW is configured.

Prerequisites

The bfd command has been run to enable BFD globally.
The mpls l2vc command has been run to configure a PW between AC interfaces.

Configuration Impact

After you configure BFD for PW, PW connectivity faults can be quickly detected. If primary and secondary PWs exist, frequent PW flapping may cause frequent traffic switchovers between the primary and secondary PWs.

Precautions

To run the bfd bind pw command to detect the connectivity of a VPWS MS-PW, ensure that the first segment of the PW is a VPWS PW with one end on a non-SPE device.
To run the bfd bind pw command to detect the connectivity of a VPWS SS-PW, ensure that the end nodes of the PW are not SPEs.
If you specify remote-peer incorrectly after choosing auto-calculate, the calculated TTL is 0 and the BFD session cannot go Up.
To run the bfd bind pw vsi command to detect the connectivity of a VPLS SS-PW, ensure that the end nodes of the PW are not SPEs.
In BGP VPWS scenarios, when BFD has been bound to a PW and the remote-peer parameter is configured, the system displays an error message, indicating that the PW's remote address cannot be specified. In LDP VPWS and LDP VPLS scenarios, the remote-peer parameter can be configured.
Static BFD for VLL PW does not support a CV type of 0x10 or 0x20 in control word mode. If the CV type in the PW negotiation result is 0x10 or 0x20, the BFD session cannot go Up.

Example

# Configure BFD for PW in TTL mode on a non-SPE device to detect the connectivity of a VPWS PW.

<HUAWEI> system-view
[~HUAWEI] bfd
[*HUAWEI-bfd] quit
[*HUAWEI] mpls
[*HUAWEI-mpls] quit
[*HUAWEI] mpls l2vpn
[*HUAWEI-l2vpn] quit
[*HUAWEI] bfd b bind pw interface GigabitEthernet0/1/8 remote-peer 1.1.1.1 pw-ttl auto-calculate