No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search

Reminder

To have a better experience, please upgrade your IE browser.

upgrade

Configuration Guide - IP Routing 01

NE05E and NE08E V300R003C10SPC500

This is NE05E and NE08E V300R003C10SPC500 Configuration Guide - IP Routing
Rate and give feedback:
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Configuring BGP Iteration Suppression in Case of Next Hop Flapping

Configuring BGP Iteration Suppression in Case of Next Hop Flapping

BGP iteration suppression in case of next hop flapping prevents the system from frequently processing changes of a large number of routes that are iterated to a flapping next hop, which reduces system resource consumption and CPU usage.

Usage Scenario

If a large number of routes are iterated to the same next hop that flaps frequently, the system will be busy processing changes of these routes, which consumes excessive system resources and leads to high CPU usage. To address this problem, configure BGP iteration suppression in case of next hop flapping.

By default, BGP iteration suppression in case of next hop flapping is enabled. After this function is enabled, BGP calculates the penalty value that starts from 0 by comparing the flapping interval with configured intervals if next hop flapping occurs. When the penalty value exceeds 10, BGP suppresses route iteration to the corresponding next hop. For example, if the intervals for increasing, retaining, and clearing the penalty value are T1, T2, and T3, respectively, BGP calculates the penalty value as follows:
  • Increases the penalty value by 1 if the flapping interval is less than T1.
  • Retains the penalty value if the flapping interval is greater than or equal to T1, but less than T2.
  • Reduces the penalty value by 1 if the flapping interval is greater than or equal to T2, but less than T3.
  • Clears the penalty value if the flapping interval is greater than or equal to T3.

By default, the intervals for increasing, retaining, and clearing the penalty value for BGP iteration suppression in case of next hop flapping are 60s, 120s, and 600s, respectively. Keeping the default values is recommended.

Pre-configuration tasks

Before configuring BGP iteration suppression in case of next hop flapping, configure basic BGP functions.

Procedure

  1. Run system-view

    The system view is displayed.

  2. Run bgp as-number

    The BGP view is displayed.

  3. Run ipv4-family unicast

    The IPv4 unicast address family view is displayed.

  4. Run undo nexthop recursive-lookup restrain disable

    BGP iteration suppression in case of next hop flapping is enabled.

    If you do not care about whether the system is busy processing route selection and advertisement and the possible high CPU usage, run the nexthop recursive-lookup restrain disable command to disable BGP iteration suppression in case of next hop flapping.

  5. Run quit

    Return to the BGP view.

  6. Run nexthop recursive-lookup restrain suppress-interval add-count-time hold-interval hold-count-time clear-interval clear-count-time

    The intervals are configured for increasing, retaining, and clearing the penalty value for BGP iteration suppression in case of next hop flapping.

  7. Run commit

    The configuration is committed.

Checking the Configurations

After configuring BGP iteration suppression in case of next hop flapping, check the configurations.

  • Run the display bgp routing-table command to check BGP public network route information.
  • Run the display bgp vpnv4 routing-table command to check BGP VPNv4 and BGP VPN route information.

# Run the display bgp routing-table network command to view BGP public network route information. The command output shows that route iteration to a specified next hop is suppressed because the next hop flaps. If only a small number of routes are iterated to the next hop, the suppression is very short; therefore, the Relay is delayed as nexthop flapped frequently field may not be displayed in this case.

<HUAWEI> display bgp routing-table 1.1.1.1
 BGP local router ID : 189.2.3.107
 Local AS number : 100
 Paths:   1 available, 1 best, 1 select, 0 best-external, 0 add-path
 BGP routing table entry information of 1.1.1.1/32:
 From: 11.1.1.2 (11.1.1.2)
 Route Duration: 0d00h01m33s
 Direct Out-interface: GigabitEthernet0/1/0
 Relay is delayed as nexthop flapped frequently
 Original nexthop: 11.1.1.2
 Qos information : 0x0
 Primary Routing Table: vrf1
 AS-path 200, origin incomplete, MED 0, pref-val 0, valid, external, best, select, active, pre 255
 Advertised to such 1 peers:
    11.1.1.2

# Run the display bgp vpnv4 routing-table network command to view BGP VPNv4 route information. The command output shows that route iteration to a specified next hop is suppressed because the next hop flaps. If only a small number of routes are iterated to the next hop, the suppression is very short; therefore, the Relay is delayed as nexthop flapped frequently field may not be displayed in this case.

<HUAWEI> display bgp vpnv4 vpn-instance vrf1 routing-table 2.2.2.2
BGP local router ID : 10.99.1.111
Local AS number : 100

VPN-Instance vrf1, Router ID 10.99.1.111:
Paths: 1 available, 1 best, 1 select, 0 best-external, 0 add-path
BGP routing table entry information of 2.2.2.2/32:
Remote-Cross route
Label information (Received/Applied): 33142/NULL
From: 3.3.3.9 (10.99.2.113) 
Route Duration: 0d00h03m13s
Relay Tunnel Out-Interface: 
Relay is delayed as nexthop flapped frequently
Original nexthop: 3.3.3.9
Qos information : 0x0 
Ext-Community: RT <1 : 1>
AS-path Nil, origin incomplete, MED 0, localpref 100, pref-val 0, valid, internal, best, select, pre 255
Not advertised to any peer yet
Translation
Download
Updated: 2019-01-14

Document ID: EDOC1100058916

Views: 34086

Downloads: 49

Average rating:
This Document Applies to these Products
Related Documents
Related Version
Share
Previous Next