bestroute add-path (BGP multi-instance VPNv4 address family view)

Function

The bestroute add-path command enables BGP Add-Path and configures the number of routes that the device can select.

The undo bestroute add-path command restores the default configuration.

By default, BGP Add-Path is not enabled.

Format

bestroute add-path path-number path-number

undo bestroute add-path

Parameters

Parameter	Description	Value
path-number path-number	Specifies the number of routes that the device can select.	The value is an integer ranging from 2 to 64.

Parameter

Description

Value

path-number path-number

Specifies the number of routes that the device can select.

The value is an integer ranging from 2 to 64.

Views

BGP multi-instance VPNv4 address family view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
bgp	write

Usage Guidelines

Usage Scenario

In a scenario with an RR and clients, if the RR has multiple routes to the same destination (with the same prefix), the RR selects an optimal route from these routes and then sends only the optimal route to its clients. Therefore, the clients have only one route to the destination. If a link along this route fails, route convergence takes a long time, which cannot meet the requirements for high reliability. To address this issue, deploy the BGP Add-Path feature on the RR. With BGP Add-Path, the RR can send two or more routes with the same prefix to a specified IBGP peer. These routes can back up each other or load-balance traffic, which ensures high reliability in data transmission.

Follow-up Procedure

Run the peer capability-advertise add-path send command to enable the RR to send Add-Path routes to a specified IBGP peer.
Run the peer advertise add-path command to configure the number of routes that the RR can send to a specified IBGP peer.

Precautions

The bestroute add-path command is run on RRs in most cases although it can be configured on any device. After the command is run, the RR can select 2 to 64 routes.
Preferred Add-Path routes participate in load balancing only if they meet load balancing requirements.
The type (labeled or unlabeled) of Add-Path routes is the same as that of the optimal route.
You need to run the peer capability-advertise add-path receive command on the IBGP peer so that the IBGP peer can learn Add-Path routes from the specified RR.

Example

# Set the number of routes that the device can select to 6.

<HUAWEI> system-view
[~HUAWEI] bgp 100 instance a
[*HUAWEI-bgp-instance-a] ipv4-family vpnv4
[*HUAWEI-bgp-instance-a-af-vpnv4] bestroute add-path path-number 6