How do I check whether LSP flapping occurs on an AR

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You can run the display mpls lsp command to check the number of LSPs. If the number of LSPs changes frequently, LSP flapping occurs. In this case, run the snmp-agent trap enable feature-name mpls_lspm command. If the alarm about LSPs is frequently generated, LSP flapping occurs. Run the undo snmp-agent trap enable command.
For example:
#Jul 25 22:49:18 2020 HUAWEI LSPM/5/TRAP:1.3.6.1.2.1.10.166.2.0.2 LSP 210958 Changes to Down
#Jul 25 22:49:19 2020 HUAWEI LSPM/5/TRAP:1.3.6.1.2.1.10.166.2.0.1 LSP 210958 Changes to Up
The preceding information shows that the LSP alternates between Up and Down.

Other related questions:
When will an LSP flap and how do I know that an LSP flap occurred
If routing flapping or LSP session flapping occurs, LSP flapping occurs. LSPs may also flap when loop detection is configured or address overlapping, multiple links, or ring topologies exist. To determine whether LSP flapping occurs, run the display mpls lsp command to check the number of LSPs. If the number of LSPs frequently changes, LSP flapping occurs. You can also run the snmp-agent trap enable feature-name mpls_lspm command to enable trap for the MPLS LSPM module. If the LSP alarms are frequently generated, LSP flapping occurs. In this case, run the undo snmp-agent trap enable command to restore the default trap settings. The following alarm information is displayed: #Jul 25 22:49:18 2020 HUAWEI LSPM/5/TRAP:1.3.6.1.2.1.10.166.2.0.2 LSP 210958 Changes to Down #Jul 25 22:49:19 2020 HUAWEI LSPM/5/TRAP:1.3.6.1.2.1.10.166.2.0.1 LSP 210958 Changes to Up

What need I check when LSP flapping occurs
When LSP flapping occurs, check the following information: Whether the peer end can be pinged. Run the display mpls ldp peer command in the system view to check the peer address (Transport-Address field). Run the ping command to check for traffic loss. Whether route flapping occurs. Run the display ip routing-table command in the system view to check all the current routing information. Set the destination address to check all the current routing information mapping the destination address. Frequently check routing information in a period to check for flapping. Whether LDP session flapping occurs. Run the display mpls ldp session command in the system view to check information about all LDP sessions. Set the peer address to check information about the LDP session with the specified peer. Frequently check LDP session information in a period to check for flapping. Whether lsp-trigger all is configured. Whether exceptions occur by enabling the debugging function.

How to check whether an ARP Conflict Occurs ?
Run the display logbuffer command to display the system log and check whether the ARP conflict occurs, resulting in slow network access.

How to check whether MPLS is enabled on an AR interface
Run the display mpls interface [ interface-type <interface-number> ] [ verbose ] command to check information about MPLS-enabled interfaces.
[Huawei] display mpls interface
Interface  Status  TE Attr  LSP Count  CRLSP Count Effective MTU
GE1/0/0    Up       Dis        2                   0                        1500
Note:
- Interface: indicates the type and number of the interface enabled with MPLS.
- Status: indicates the status of the interface, which is Up or Down.
- TE Attr: indicates whether the TE attribute is enabled. Dis indicates that the TE attribute is disabled, and En indicates that the TE attribute is enabled.
- LSP Count: indicates the number of established LSPs on the interface.
- CRLSP Count: indicates the number of established CR-LSPs on the interface.
- Effective MTU: indicates the MTU used for forwarding MPLS packets.

How can I check whether LDP GR is performed on the AR router
Run the display mpls graceful-restart command to check the GR status. [Huawei] display mpls graceful-restart Protocol GR state GR start time GR type LDP Normal - - CRLDP Normal - - RSVP Normal - - BGP Normal - - L3VPN Normal - - STATIC Normal - - CRSTATIC Normal - - BGP IPV6 Normal - - STATIC HA Normal - - L3VPN IPV6 Normal - - STATIC TP Normal - - Parameters are described as follows: Protocol: protocol type GR state: If the value is Restarting, GR is being performed. GR start time: The value is displayed as - if GR does not start. GR type - System restart - Protocol restart The value is displayed as - if GR does not start.

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