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Command Reference

CloudEngine 8800, 7800, 6800, and 5800 V200R002C50

This document describes all the configuration commands of the device, including the command function, syntax, parameters, views, default level, usage guidelines, examples, and related commands.
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prefix limit

prefix limit

Function

The prefix limit command sets a limit on the maximum number of prefixes supported in the existing VPN instance address family, preventing the PE from importing excessive VPN route prefixes.

The undo prefix limit command restores the default setting.

By default, the maximum number of VPN route prefixes is not limited.

NOTE:

CE6810LI series does not support this command.

Format

prefix limit number { alert-percent [ route-unchanged ] | simply-alert }

undo prefix limit

Parameters

Parameter Description Value
number Specifies the maximum number of prefixes supported in the VPN instance address family. The value is an integer ranging from 1 to 4294967295.
alert-percent Specifies the proportion of the alarm threshold to the maximum number of prefixes. When the number of prefixes in theVPN instance address family exceeds number x alert-percent/100, alarms are displayed. The VPN route prefixes, however, can still join the VPN routing table. When the number of the prefixes exceeds the number, the subsequent prefixes are discarded. The value is an integer ranging from 1 to 100.
route-unchanged Indicates that the routing table remains unchanged. By default, route-unchanged is not configured. When the number of prefixes in the routing table is greater than the value of the parameter number, routes are processed as follows:
  • If route-unchanged is configured, routes in the routing table remain unchanged.
  • If route-unchanged is not configured, all routes in the routing table are deleted and then re-added.
-
simply-alert Indicates that when the number of VPN route prefixes exceeds number, prefixes can still join the VPN routing table and alarms are displayed. On the device, however, the subsequent VPN route prefixes are discarded after the total number of the unicast prefixes of the private network and the public network reaches the upper limit. -

Views

VPN instance view, VPN instance IPv4 address family view or VPN instance IPv6 address family view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

If many useless route prefixes imported into a VPN instance constitute a large proportion of the route prefixes on a device, run the prefix limit command to set a limit on the maximum number of prefixes supported by the VPN instance. After the prefix limit command is run in the current VPN instance address family, if the number of route prefixes reaches the set limit, the system will generate an alarm to instruct the user to check the validity of route prefixes of the VPN instance.

Prerequisites

The route-distinguisher command has been executed to set the RD of the VPN instance.

Precautions

After the command is run, the excess route prefixes of the current VPN instance address family will be discarded.

If the number of route prefixes exceeds the set limit and the undo prefix limit command is run, the system will receive the route prefixes from routing tables generated by protocols to create a private network routing table.

The prefix limit command can prevent the routing table of the current VPN instance address family on a PE from importing too many route prefixes, but cannot prevent the PE from importing excessive route prefixes from other PEs. Therefore, configuring both the prefix limit and peer route-limit commands is recommended.

When the number of prefixes exceeds the upper limit, the prefix limit command with simply-alert specified enables the device to display only alarms and allows the device to add prefixes to the routing table.

Example

# Configure the system to only generate alarms when the number of prefixes exceeds the maximum number 1000 in the VPN instance named vpn1.

<HUAWEI> system-view
[~HUAWEI] ip vpn-instance vpn1
[*HUAWEI-vpn-instance-vpn1] ipv4-family
[*HUAWEI-vpn-instance-vpn1-af-ipv4] route-distinguisher 100:1
[*HUAWEI-vpn-instance-vpn1-af-ipv4] prefix limit 1000 simply-alert
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Updated: 2019-03-21

Document ID: EDOC1000166501

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