ospf smart-discover multi-area

Function

The ospf smart-discover multi-area command enables smart-discover on a multi-area adjacency interface.

The undo ospf smart-discover multi-area command disables smart-discover on a multi-area adjacency interface.

By default, smart-discover is disabled on multi-area adjacency interfaces.

Format

ospf smart-discover multi-area { area-id | area-id }

undo ospf smart-discover multi-area { area-id | area-id }

Parameters

Parameter	Description	Value
area-id	Specifies the ID of an OSPF area.	The value can be a decimal integer ranging from 0 to 4294967295 or in the format of an IP address.

Parameter

Description

Value

area-id

Specifies the ID of an OSPF area.

The value can be a decimal integer ranging from 0 to 4294967295 or in the format of an IP address.

Views

100GE interface view, 10GE interface view, 25GE sub-interface view, 25GE interface view, 400GE interface view, 40GE interface view, 50GE sub-interface view, 50GE interface view, Eth-Trunk interface view, FlexE interface view, GE optical interface view, GE electrical interface view, GMPLS-UNI interface view, Global VE sub-interface view, Tunnel interface view, VBDIF interface view, VE sub-interface view, VLANIF interface view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
ospf	write

Usage Guidelines

Usage Scenario

Generally, routers periodically send Hello packets through OSPF interfaces to establish and maintain OSPF neighbor relationships and elect a DR or BDR on a multi-access network (broadcast or NBMA network). However, Hello packets are not sent to neighbors until the Hello timer expires, which slows down the establishment of neighbor relationships and DR or BDR election.

To address this problem, run the ospf smart-discover multi-area command to enable smart-discover on a multi-area adjacency interface so that Hello packets are sent to neighbors immediately, regardless of the Hello timer.

Prerequisites

The ospf enable multi-area command has been run.

Implementation Procedure

If smart-discover is enabled on a broadcast or NBMA interface, it works as follows:

If the neighbor status reaches 2-way for the first time or returns to Init from 2-way or a higher state, the smart-discover-capable interface sends Hello packets to its neighbor immediately when detecting that the neighbor's status changes.
If the interface status of the DR or BDR on the multi-access network changes, the smart-discover-capable interface sends Hello packets within its network segment and participates in DR or BDR election.
The fast neighbor relationship establishment process on a P2P or P2MP network is similar to that on a broadcast or NBMA network.

Configuration Impact

The interval at which Hello packets are sent is determined by the interval at which Hello packets are sent.

Precautions

The default interval for sending Hello packets varies according to the network type.

Example

# Enable smart-discover on a multi-area adjacency interface.

<HUAWEI> system-view
[~HUAWEI] ospf 1
[*HUAWEI-ospf-1] area 0
[*HUAWEI-ospf-1-area-0.0.0.0] quit
[*HUAWEI-ospf-1] area 1
[*HUAWEI-ospf-1-area-0.0.0.1] quit
[*HUAWEI-ospf-1] quit
[*HUAWEI] interface GigabitEthernet0/1/0
[*HUAWEI-GigabitEthernet0/1/0] ospf enable 1 area 0
[*HUAWEI-GigabitEthernet0/1/0] ospf enable multi-area 1
[*HUAWEI-GigabitEthernet0/1/0] ospf smart-discover multi-area 1