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ME60 V800R010C10SPC500 Configuration Guide - IP Routing 01

This is ME60 V800R010C10SPC500 Configuration Guide - IP Routing
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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 Route Dampening

Configuring BGP Route Dampening

BGP route dampening can be configured to suppress unstable routes.

Usage Scenario

The main cause of route instability is route flapping. A route is considered to be flapping when it repeatedly appears and then disappears in the routing table. BGP is generally applied to complex networks where routes change frequently. Frequent route flapping consumes lots of bandwidth and CPU resources and even seriously affects network operations.

BGP route dampening prevents frequent route flapping by using a penalty value to measure route stability. When a route flaps for the first time, a penalty value is assigned to the route. Later, each time the route flaps, the penalty value of the route increases by a specific value. The greater the penalty value, the less stable the route. If the penalty value of a route exceeds the pre-defined threshold, the route will not be advertised until the penalty value of the route reduces to the reuse threshold.

Route dampening applies only to EBGP routes and VPNv4 IBGP routes. IBGP routes (except VPNv4 IBGP routes) cannot be dampened because IBGP routing tables contain the routes from the local AS, which require that the forwarding entries be the same on IBGP peers in the AS. If IBGP routes are dampened, the forwarding entries may be inconsistent because dampening parameters may vary among these IBGP peers.

Pre-configuration Tasks

Before configuring BGP route dampening, complete the following task:

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. Configuring BGP route dampening parameters

    • Configuring EBGP route dampening parameters
      1. Run the ipv4-family unicast command to display the IPv4 unicast address family view.
      2. Run the dampening [ half-life-reach reuse suppress ceiling | route-policy route-policy-name ] * [ update-standard ] command to set the EBGP route dampening parameters.
    • Configuring IBGP route dampening parameters
      1. Run the ipv4-family vpnv4 command to display the BGP-VPNv4 address family view.
      2. Run the dampening ibgp [ half-life-reach reuse suppress ceiling | route-policy route-policy-name ] * [ update-standard ] command to set the IBGP route dampening parameters.

    When you configure BGP route dampening, the values of reuse, suppress, and ceiling should meet the relationship of reuse<suppress<ceiling.

    If routes are differentiated based on policies and the dampening command is run to reference a route-policy, BGP can use different route dampening parameters to suppress different routes.

  5. Run commit

    The configuration is committed.

Checking the Configurations

After BGP route dampening is configured, you can check whether the configuration is correct.

  • Run the display bgp routing-table flap-info [ regular-expression as-regular-expression | as-path-filter { as-path-filter-number | as-path-filter-name } | network-address [ { mask | mask-length } [ longer-match ] ] ] command to check route flapping statistics.

  • Run the display bgp routing-table time-range start-time end-time command to view BGP routes that flap within the specified time period.

  • Run the display bgp routing-table dampened command to check dampened BGP routes.

  • Run the display bgp routing-table dampening parameter command to check configured BGP route dampening parameters.

# Run the display bgp routing-table flap-info command to view BGP route flapping statistics. For example:
<HUAWEI> display bgp routing-table flap-info
 BGP Local router ID is 20.20.200.201
 Status codes: * - valid, > - best, d - damped, x - best external, a - add path,
               h - history,  i - internal, s - suppressed,
               Origin codes: i - IGP, e - EGP, ? - incomplete
 RPKI validation codes: V - valid, I - invalid, N - not-found

 Total Number of Routes: 7
     Network         From            Flaps Duration     Reuse  Path/Ogn

 d   129.1.1.0       20.20.200.200   5      00:00:36  00:40:47  600i
 *>  129.1.1.0       20.20.200.202   1      00:04:07            100?
 d   129.1.2.0       20.20.200.200   5      00:00:36  00:40:47  600i
 *>  129.1.2.0       20.20.200.202   1      00:04:07            100?
 d   129.1.3.0       20.20.200.200   5      00:00:36  00:40:47  600i
 d   129.1.4.0       20.20.200.200   5      00:00:36  00:40:47  600i
 d   129.1.5.0       20.20.200.200   5      00:00:36  00:40:47  600i

# Run the display bgp routing-table dampened command to view dampened BGP routes. For example:

<HUAWEI> display bgp routing-table dampened
 BGP Local router ID is 223.1.41.102
 Status codes: * - valid, > - best, d - damped, x - best external, a - add path,
               h - history,  i - internal, s - suppressed, S - Stale
               Origin : i - IGP, e - EGP, ? - incomplete
 RPKI validation codes: V - valid, I - invalid, N - not-found

 Total Number of Routes: 8
     Network            From              Reuse     Path/Origin
  d  8.6.244.0/23       223.1.41.247      01:06:25  65534 4837 174 11096 6356i
  d  9.17.79.0/24       223.1.41.247      01:06:25  65534 837 3356 23504 29777i
  d  9.17.110.0/24      223.1.41.247      01:06:25  65534 837 3356 23504 29777i
  d  61.57.144.0/20     223.1.41.247      01:06:25  65534 4837 10026 9924 18429,18429i
  d  63.76.216.0/24     223.1.41.247      01:06:25  65534 4837 701 26959i
  d  63.78.142.0/24     223.1.41.247      01:06:25  65534 4837 701 26959i
  d  63.115.136.0/23    223.1.41.247      01:06:25  65534 4837 701 26956i
  d  65.243.170.0/24    223.1.41.247      01:06:25  65534 4837 701 26959i

# Run the display bgp routing-table dampening parameter command to view configured BGP route dampening parameters. For example:

<HUAWEI> display bgp routing-table dampening parameter
 Maximum Suppress Time(in second) : 3973
 Ceiling Value                    : 16000
 Reuse Value                      : 750
 HalfLife Time(in  second)        : 900
 Suppress-Limit                   : 2000
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Updated: 2019-01-04

Document ID: EDOC1100059437

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