Configuring OSPFv3 Neighbor Relationship Flapping Suppression

Usage Scenario

If an interface carrying OSPFv3 services alternates between Up and Down, OSPFv3 neighbor relationship flapping occurs on the interface. During the flapping, OSPFv3 frequently sends Hello packets to reestablish the neighbor relationship, synchronizes LSDBs, and recalculates routes. In this process, a large number of packets are exchanged, adversely affecting neighbor relationship stability, OSPFv3 services, and other OSPFv3-dependent services. OSPFv3 neighbor relationship flapping suppression can address this problem by delaying OSPFv3 neighbor relationship reestablishment or preventing service traffic from passing through flapping links.

The following steps are optional, choose them as required.

Pre-configuration Tasks

Before configuring OSPFv3 neighbor relationship flapping suppression, complete the following tasks:

Configure an IP address for each interface to ensure that neighboring routers are reachable at the network layer.
Configure basic OSPFv3 functions.

Procedure

Run system-view
The system view is displayed.

By default, OSPFv3 neighbor relationship flapping suppression is enabled globally. To disable this function globally, run the suppress-flapping peer disable command.
Run interface interface-type interface-number
The interface view is displayed.

By default, OSPFv3 neighbor relationship flapping suppression is enabled on all interfaces in the same OSPFv3 process. To disable the function from one of the interfaces, run the ospfv3 suppress-flapping peer disable command.
Run ospfv3 suppress-flapping peer hold-down interval [ instance instance-id ]
The Hold-down mode is configured, and its duration is set.

Flapping suppression works in either Hold-down or Hold-max-cost mode.
- Hold-down mode: In the case of frequent flooding and topology changes during neighbor relationship establishment, interfaces prevent neighbor relationship reestablishment during Hold-down suppression, which minimizes LSDB synchronization attempts and packet exchanges.
- Hold-max-cost mode: If the traffic forwarding path changes frequently, interfaces use 65535 as the cost of the flapping link during Hold-max-cost suppression, which prevents traffic from passing through the flapping link.
Flapping suppression can also work first in Hold-down mode and then in Hold-max-cost mode.

By default, the Hold-max-cost mode takes effect.

To disable the Hold-max-cost mode, run the ospfv3 suppress-flapping peer hold-max-cost disable [ instance instance-id ] command.
Run ospfv3 suppress-flapping peer { detecting-interval detecting-interval | threshold threshold | resume-interval resume-interval } ^* [ instance instance-id ]
Detection parameters are configured for OSPFv3 neighbor relationship flapping suppression.

Each OSPFv3 interface on which OSPFv3 neighbor relationship flapping suppression is enabled starts a flapping counter. If the interval between two successive neighbor status changes from Full to a non-Full state is shorter than detecting-interval, a valid flapping_event is recorded, and the flapping_count is incremented by 1. When the flapping_count reaches or exceeds threshold, flapping suppression takes effect. If the interval between two successive neighbor status changes from Full to a non-Full state is longer than resume-interval, the flapping_count is reset.

The value of resume-interval must be greater than that of detecting-interval.

By default, the detection interval of OSPFv3 neighbor relationship flapping suppression is 3s, the suppression threshold is 30, and the interval for exiting from suppression is 10s. Using the default detection parameters is recommended.
Run quit
The system view is displayed.
Run quit
The user view is displayed.
Run reset ospfv3 process-id suppress-flapping peer [ interface-type interface-number [ instance instance-id ] ]
Interfaces are forced to exit from OSPFv3 neighbor relationship flapping suppression.
Interfaces exit from flapping suppression in the following scenarios:
- The suppression timer expires.
- The corresponding OSPFv3 process is reset.
- An OSPFv3 neighbor is reset.
- OSPFv3 neighbor relationship flapping suppression is disabled globally using the suppress-flapping peer disable (OSPFv3) command in the OSPF view.
- The reset ospfv3 suppress-flapping peer command is run.

Verifying the Configuration

Run the display ospfv3 [ process-id ] interface [ area area-id ] [ interface-type interface-number ] command to check the status of OSPFv3 neighbor relationship flapping suppression.

<HUAWEI> display ospfv3 interface vlanif 100

 VLANIF100 is up, line protocol is up
  Interface ID 0x7
  Interface MTU 1500 
  IPv6 Prefixes
    FE80::2E0:74FF:FE00:8201 (Link-Local Address)
    45::55:5/125
  OSPFv3 Process (1), Area 0.0.0.0, Instance ID 0
    Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
    Transmit Delay is 1 sec, State Backup, Priority 1
    Designated Router (ID) 4.4.4.4
    Interface Address FE80::2E0:4FF:FE09:8201
    Backup Designated Router (ID) 1.1.1.1
    Interface Address FE80::2E0:74FF:FE00:8201
    Timer interval configured, Hello 10, Dead 40, Wait 40, Retransmit 5
       Hello due in 00:00:09
    Neighbor Count is 1, Adjacent neighbor count is 1
    Interface Event 3, Lsa Count 2, Lsa Checksum 0x15084
    Interface Physical BandwidthHigh 0, BandwidthLow 100000000
    Suppress flapping peer: enable(start: 2016-01-29 12:09:36-08:00, remain-interval: 500s)

Suppress flapping peer in the command output indicates the current suppression mode (enable), time when the flapping suppression started, and the remaining time of the flapping suppression.