English

Examples: Configuring BGP Flap Damping

date_range 13-Sep-17

Understanding Damping Parameters

BGP route flapping describes the situation in which BGP systems send an excessive number of update messages to advertise network reachability information. BGP flap damping is a method of reducing the number of update messages sent between BGP peers, thereby reducing the load on these peers, without adversely affecting the route convergence time for stable routes.

Flap damping reduces the number of update messages by marking routes as ineligible for selection as the active or preferable route. Marking routes in this way leads to some delay, or suppression, in the propagation of route information, but the result is increased network stability. You typically apply flap damping to external BGP (EBGP) routes (routes in different ASs). You can also apply flap damping within a confederation, between confederation member ASs. Because routing consistency within an AS is important, do not apply flap damping to internal BGP (IBGP) routes. (If you do, it is ignored.)

There is an exception that rule. Starting in Junos OS Release 12.2, you can apply flap damping at the address family level. In a Junos OS Release 12.2 or later installation, when you apply flap damping at the address family level, it works for both IBGP and EBGP.

By default, route flap damping is not enabled. Damping is applied to external peers and to peers at confederation boundaries.

When you enable damping, default parameters are applied, as summarized in Table 1.

Table 1: Damping Parameters

Damping Parameter	Description	Default Value	Possible Values
half-life `minutes`	Decay half-life—Number of minutes after which an arbitrary value is halved if a route stays stable.	15 (minutes)	1 through 45
max-suppress `minutes`	Maximum hold-down time for a route, in minutes.	60 (minutes)	1 through 720
reuse	Reuse threshold—Arbitrary value below which a suppressed route can be used again.	750	1 through 20,000
suppress	Cutoff (suppression) threshold—Arbitrary value above which a route can no longer be used or included in advertisements.	3000	1 through 20,000

To change the default BGP flap damping values, you define actions by creating a named set of damping parameters and including it in a routing policy with the damping action. For the damping routing policy to work, you also must enable BGP route flap damping.

Example: Configuring BGP Route Flap Damping Parameters

This example shows how to configure damping parameters.

Requirements

Before you begin, configure router interfaces and configure routing protocols.

Overview

This example has three routing devices. Device R2 has external BGP (EBGP) connections with Device R1 and Device R3.

Device R1 and Device R3 have some static routes configured for testing purposes, and these static routes are advertised through BGP to Device R2.

Device R2 damps routes received from Device R1 and Device R3 according to these criteria:

Damp all prefixes with a mask length equal to or greater than 17 more aggressively than routes with a mask length between 9 and 16.
Damp routes with a mask length between 0 and 8, inclusive, less than routes with a mask length greater than 8.
Do not damp the 10.128.0.0/9 prefix at all.

The routing policy is evaluated when routes are being exported from the routing table into the forwarding table. Only the active routes are exported from the routing table.

Figure 1 shows the sample network.

CLI Quick Configuration shows the configuration for all of the devices in Figure 1.

The section Step-by-Step Procedure describes the steps on Device R2.

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

Device R1

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set interfaces fe-1/2/0 unit 0 family inet
address 10.0.0.1/30
set interfaces lo0 unit 0 family inet address
192.168.0.1/32
set protocols bgp group ext type external
set protocols bgp group ext export send-direct-and-static
set protocols bgp group ext peer-as 200
set protocols bgp group ext neighbor 10.0.0.2
set policy-options policy-statement send-direct-and-static
term 1 from protocol direct
set policy-options policy-statement send-direct-and-static
term 1 from protocol static
set policy-options policy-statement send-direct-and-static
term 1 then accept
set routing-options static route 172.16.0.0/16
reject
set routing-options static route 172.16.128.0/17
reject
set routing-options static route 172.16.192.0/20
reject
set routing-options static route 10.0.0.0/9
reject
set routing-options static route 172.16.233.0/7
reject
set routing-options static route 10.224.0.0/11
reject
set routing-options static route 0.0.0.0/0
reject
set routing-options autonomous-system 100

Device R2

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set interfaces fe-1/2/0 unit 0 family inet
address 10.0.0.2/30
set interfaces fe-1/2/1 unit 0 family inet
address 10.1.0.1/30
set interfaces lo0 unit 0 family inet address
192.168.0.2/32
set protocols bgp damping
set protocols bgp group ext type external
set protocols bgp group ext import damp
set protocols bgp group ext export send-direct
set protocols bgp group ext neighbor 10.0.0.1
peer-as 100
set protocols bgp group ext neighbor 10.1.0.2
peer-as 300
set policy-options policy-statement damp term
1 from route-filter 10.128.0.0/9 exact damping dry
set policy-options policy-statement damp term
1 from route-filter 0.0.0.0/0 prefix-length-range /0-/8 damping timid
set policy-options policy-statement damp term
1 from route-filter 0.0.0.0/0 prefix-length-range /17-/32 damping
aggressive
set policy-options policy-statement send-direct
term 1 from protocol direct
set policy-options policy-statement send-direct
term 1 then accept
set policy-options damping aggressive half-life
30
set policy-options damping aggressive suppress
2500
set policy-options damping timid half-life
5
set policy-options damping dry disable
set routing-options autonomous-system 200

Device R3

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set interfaces fe-1/2/1 unit 0 family inet
address 10.1.0.2/30
set interfaces lo0 unit 0 family inet address
192.168.0.3/32
set protocols bgp group ext type external
set protocols bgp group ext export send-direct-and-static
set protocols bgp group ext peer-as 200
set protocols bgp group ext neighbor 10.1.0.1
set policy-options policy-statement send-direct-and-static
term 1 from protocol direct
set policy-options policy-statement send-direct-and-static
term 1 from protocol static
set policy-options policy-statement send-direct-and-static
term 1 then accept
set routing-options static route 10.128.0.0/9
reject
set routing-options autonomous-system 300

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.

To configure damping parameters:

Configure the interfaces.

[edit interfaces]
user@R2# set fe-1/2/0 unit 0 family inet address 10.0.0.2/30

user@R2# set fe-1/2/1 unit 0 family inet address 10.1.0.1/30

user@R2# set lo0 unit 0 family inet address 192.168.0.2/32
Configure the BGP neighbors.

[edit protocols bgp group ext]
user@R2# set type external
user@R2# set neighbor 10.0.0.1 peer-as 100
user@R2# set neighbor 10.1.0.2 peer-as 300
Create and configure the damping parameter groups.

[edit policy-options]
user@R2# set damping aggressive half-life 30
user@R2# set damping aggressive suppress 2500
user@R2# set damping timid half-life 5
user@R2# set damping dry disable
Configure the damping policy.

[edit policy-options policy-statement damp term 1]
user@R2# set from route-filter 10.128.0.0/9 exact damping dry
user@R2# set from route-filter 0.0.0.0/0 prefix-length-range /0-/8 damping timid
user@R2# set from route-filter 0.0.0.0/0 prefix-length-range /17-/32 damping aggressive
Enable damping for BGP.

[edit protocols bgp]
user@R2# set damping
Apply the policy as an import policy for the BGP neighbor.

[edit protocols bgp group ext]
user@R2# set import damp

Note
You can refer to the same routing policy one or more times in the same or different import statements.
Configure an export policy.

[edit policy-options policy-statement send-direct term 1]
user@R2# set from protocol direct
user@R2# set then accept
Apply the export policy.

[edit protocols bgp group ext]
user@R2# set export send-direct
Configure the autonomous system (AS) number.

[edit routing-options]
user@R2# set autonomous-system 200

Results

From configuration mode, confirm your configuration by issuing the show interfaces, show protocols, show policy-options, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

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user@R2# show interfaces
fe-1/2/0 {
unit 0 {
family inet {
address 10.0.0.2/30;
}
}
}
fe-1/2/1 {
unit 0 {
family inet {
address 10.1.0.1/30;
}
}
}
lo0 {
unit 0 {
family inet {
address 192.168.0.2/32;
}
}
}

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user@R2# show protocols
bgp {
damping;
group ext {
type external;
import damp;
export send-direct;
neighbor 10.0.0.1 {
peer-as 100;
}
neighbor 10.1.0.2 {
peer-as 300;
}
}
}

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user@R2# show policy-options
policy-statement damp {
term 1 {
from {
route-filter 10.128.0.0/9 exact damping dry;
route-filter 0.0.0.0/0 prefix-length-range /0-/8 damping
timid;
route-filter 0.0.0.0/0 prefix-length-range /17-/32 damping
aggressive;
}
}
}
policy-statement send-direct {
term 1 {
from protocol direct;
then accept;
}
}
damping aggressive {
half-life 30;
suppress 2500;
}
damping timid {
half-life 5;
}
damping dry {
disable;
}

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user@R2# show routing-options
autonomous-system 200;

If you are done configuring the device, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

Causing Some Routes to Flap

Purpose

To verify your route flap damping policy, some routes must flap. Having a live Internet feed almost guarantees that a certain number of route flaps will be present. If you have control over a remote system that is advertising the routes, you can modify the advertising router's policy to effect the advertisement and withdrawal of all routes or of a given prefix. In a test environment, you can cause routes to flap by clearing the BGP neighbors or by restarting the routing process on the BGP neighbors, as shown here.

Action

From operational mode on Device R1 and Device R3, enter the restart routing command.

Caution

Use this command cautiously in a production network.

user@R1> restart routing

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R1 started, pid 10474

user@R3> restart routing

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R3 started, pid 10478

Meaning

On Device R2, all of the routes from the neighbors are withdrawn and re-advertised.

Checking the Route Flaps

Purpose

View the number of neighbor flaps.

Action

From operational mode, enter the show bgp summary command.

user@R2> show bgp summary

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Groups: 1 Peers: 2 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
inet.0               
                      12          1         11          0         11          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
10.0.0.1                100         10         10       0       4        2:50 0/9/0/9              0/0/0/0
10.1.0.2                300         10         10       0       4        2:53 1/3/1/2              0/0/0/0

Meaning

This output was captured after the routing process was restarted on Device R2’s neighbors four times.

Verifying Route Flap Damping

Purpose

Verify that routes are being hidden due to damping.

Action

From operational mode, enter the show route damping suppressed command.

user@R2> show route damping suppressed

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inet.0: 15 destinations, 17 routes (6 active, 0 holddown, 11 hidden)
+ = Active Route, - = Last Active, * = Both

0.0.0.0/0           [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0
10.0.0.0/9          [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0
10.0.0.0/30         [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0
10.1.0.0/30         [BGP ] 00:00:15, localpref 100
                      AS path: 300 I, validation-state: unverified
                    > to 10.1.0.2 via fe-1/2/1.0
10.224.0.0/11       [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0
172.16.0.0/16       [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0
172.16.128.0/17     [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0
172.16.192.0/20     [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0
192.168.0.1/32      [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0
192.168.0.3/32      [BGP ] 00:00:15, localpref 100
                      AS path: 300 I, validation-state: unverified
                    > to 10.1.0.2 via fe-1/2/1.0
172.16.233.0/7         [BGP ] 00:00:12, localpref 100
                      AS path: 100 I, validation-state: unverified
                    > to 10.0.0.1 via fe-1/2/0.0

Meaning

The output shows some routing instability. Eleven routes are hidden due to damping.

Displaying the Details of a Damped Route

Purpose

Display the details of damped routes.

Action

From operational mode, enter the show route damping suppressed 172.16.192.0/20 detail command.

user@R2> show route damping suppressed 172.16.192.0/20
detail

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inet.0: 15 destinations, 17 routes (6 active, 0 holddown, 11 hidden)
172.16.192.0/20 (1 entry, 0 announced)
         BGP                 /-101
                Next hop type: Router, Next hop index: 758
                Address: 0x9414484
                Next-hop reference count: 9
                Source: 10.0.0.1
                Next hop: 10.0.0.1 via fe-1/2/0.0, selected
                Session Id: 0x100201
                State: <Hidden Ext>
                Local AS:   200 Peer AS:   100
                Age: 52 
                Validation State: unverified 
                Task: BGP_100.10.0.0.1+55922
                AS path: 100 I
                Localpref: 100
                Router ID: 192.168.0.1
                Merit (last update/now): 4278/4196
                damping-parameters: aggressive
                Last update:       00:00:52 First update:       01:01:55
                Flaps: 8
                Suppressed. Reusable in:       01:14:40
                Preference will be: 170

Meaning

This output indicates that the displayed route has a mask length that is equal to or greater than /17, and confirms that it has been correctly mapped to the aggressive damping profile. You can also see the route’s current (and last) figure of merit value, and when the route is expected to become active if it remains stable.

Verifying That Default Damping Parameters Are in Effect

Purpose

Locating a damped route with a /16 mask confirms that the default parameters are in effect.

Action

From operational mode, enter the show route damping suppressed detail | match 0/16 command.

user@R2> show route damping suppressed detail
| match 0/16

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172.16.0.0/16 (1 entry, 0 announced)

user@R2> show route damping suppressed 172.16.0.0/16
detail

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inet.0: 15 destinations, 17 routes (6 active, 0 holddown, 11 hidden)
172.16.0.0/16 (1 entry, 0 announced)
         BGP                 /-101
                Next hop type: Router, Next hop index: 758
                Address: 0x9414484
                Next-hop reference count: 9
                Source: 10.0.0.1
                Next hop: 10.0.0.1 via fe-1/2/0.0, selected
                Session Id: 0x100201
                State: <Hidden Ext>
                Local AS:   200 Peer AS:   100
                Age: 1:58 
                Validation State: unverified 
                Task: BGP_100.10.0.0.1+55922
                AS path: 100 I
                Localpref: 100
                Router ID: 192.168.0.1
                Merit (last update/now): 3486/3202
                Default damping parameters used
                Last update:       00:01:58 First update:       01:03:01
                Flaps: 8
                Suppressed. Reusable in:       00:31:40
                Preference will be: 170

Meaning

Routes with a /16 mask are not impacted by the custom damping rules. Therefore, the default damping rules are in effect.

To repeat, the custom rules are as follows:

Damp all prefixes with a mask length equal to or greater than 17 more aggressively than routes with a mask length between 9 and 16.
Damp routes with a mask length between 0 and 8, inclusive, less than routes with a mask length greater than 8.
Do not damp the 10.128.0.0/9 prefix at all.

Filtering the Damping Information

Purpose

Use OR groupings or cascaded piping to simplify the determination of what damping profile is being used for routes with a given mask length.

Action

From operational mode, enter the show route damping suppressed command.

user@R2> show route damping suppressed detail
| match "0 announced | damp"

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0.0.0.0/0 (1 entry, 0 announced)
                damping-parameters: timid
10.0.0.0/9 (1 entry, 0 announced)
                Default damping parameters used
                damping-parameters: aggressive
                damping-parameters: aggressive
10.224.0.0/11 (1 entry, 0 announced)
                Default damping parameters used
172.16.0.0/16 (1 entry, 0 announced)
                Default damping parameters used
172.16.128.0/17 (1 entry, 0 announced)
                damping-parameters: aggressive
172.16.192.0/20 (1 entry, 0 announced)
                damping-parameters: aggressive
192.168.0.1/32 (1 entry, 0 announced)
                damping-parameters: aggressive
192.168.0.3/32 (1 entry, 0 announced)
                damping-parameters: aggressive
172.16.233.0/7 (1 entry, 0 announced)
                damping-parameters: timid

Meaning

When you are satisfied that your EBGP routes are correctly associated with a damping profile, you can issue the clear bgp damping operational mode command to restore an active status to your damped routes, which will return your connectivity to normal operation.

Example: Configuring BGP Route Flap Damping Based on the MBGP MVPN Address Family

This example shows how to configure an multiprotocol BGP multicast VPN (also called Next-Generation MVPN) with BGP route flap damping.

Requirements

This example uses Junos OS Release 12.2. BGP route flap damping support for MBGP MVPN, specifically, and on an address family basis, in general, is introduced in Junos OS Release 12.2.

Overview

BGP route flap damping helps to diminish route instability caused by routes being repeatedly withdrawn and readvertised when a link is intermittently failing.

This example uses the default damping parameters and demonstrates an MBGP MVPN scenario with three provider edge (PE) routing devices, three customer edge (CE) routing devices, and one provider (P) routing device.

Figure 2 shows the topology used in this example.

On PE Device R4, BGP route flap damping is configured for address family inet-mvpn. A routing policy called dampPolicy uses the nlri-route-type match condition to damp only MVPN route types 3, 4, and 5. All other MVPN route types are not damped.

This example shows the full configuration on all devices in the CLI Quick Configuration section. The Configuring Device R4 section shows the step-by-step configuration for PE Device R4.

Configuration

CLI Quick Configuration

Device R1

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set interfaces ge-1/2/0 unit 1 family inet
address 10.1.1.1/30
set interfaces ge-1/2/0 unit 1 family mpls
set interfaces lo0 unit 1 family inet address
172.16.1.1/32
set protocols ospf area 0.0.0.0 interface
lo0.1 passive
set protocols ospf area 0.0.0.0 interface
ge-1/2/0.1
set protocols pim rp static address 172.16.100.1
set protocols pim interface all
set routing-options router-id 172.16.1.1

Device R2

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set interfaces ge-1/2/0 unit 2 family inet
address 10.1.1.2/30
set interfaces ge-1/2/0 unit 2 family mpls
set interfaces ge-1/2/1 unit 5 family inet
address 10.1.1.5/30
set interfaces ge-1/2/1 unit 5 family mpls
set interfaces vt-1/2/0 unit 2 family inet
set interfaces lo0 unit 2 family inet address
172.16.1.2/32
set interfaces lo0 unit 102 family inet address
172.16.100.1/32
set protocols mpls interface ge-1/2/1.5
set protocols bgp group ibgp type internal
set protocols bgp group ibgp local-address
172.16.1.2
set protocols bgp group ibgp family inet-vpn
any
set protocols bgp group ibgp family inet-mvpn
signaling
set protocols bgp group ibgp neighbor 172.16.1.4
set protocols bgp group ibgp neighbor 172.16.1.5
set protocols ospf area 0.0.0.0 interface
lo0.2 passive
set protocols ospf area 0.0.0.0 interface
ge-1/2/1.5
set protocols ldp interface ge-1/2/1.5
set protocols ldp p2mp
set policy-options policy-statement parent_vpn_routes
from protocol bgp
set policy-options policy-statement parent_vpn_routes
then accept
set routing-instances vpn-1 instance-type
vrf
set routing-instances vpn-1 interface ge-1/2/0.2
set routing-instances vpn-1 interface vt-1/2/0.2
set routing-instances vpn-1 interface lo0.102
set routing-instances vpn-1 route-distinguisher
100:100
set routing-instances vpn-1 provider-tunnel
ldp-p2mp
set routing-instances vpn-1 vrf-target target:1:1
set routing-instances vpn-1 protocols ospf
export parent_vpn_routes
set routing-instances vpn-1 protocols ospf
area 0.0.0.0 interface lo0.102 passive
set routing-instances vpn-1 protocols ospf
area 0.0.0.0 interface ge-1/2/0.2
set routing-instances vpn-1 protocols pim
rp static address 172.16.1.2 with 172.16.4.1100.1
set routing-instances vpn-1 protocols pim
interface ge-1/2/0.2 mode sparse
set routing-instances vpn-1 protocols mvpn
set routing-options router-id 172.16.1.2
set routing-options autonomous-system 1001

Device R3

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set interfaces ge-1/2/0 unit 6 family inet
address 10.1.1.6/30
set interfaces ge-1/2/0 unit 6 family mpls
set interfaces ge-1/2/1 unit 9 family inet
address 10.1.1.9/30
set interfaces ge-1/2/1 unit 9 family mpls
set interfaces ge-1/2/2 unit 13 family inet
address 10.1.1.13/30
set interfaces ge-1/2/2 unit 13 family mpls
set interfaces lo0 unit 3 family inet address
172.16.1.3/32
set protocols mpls interface ge-1/2/0.6
set protocols mpls interface ge-1/2/1.9
set protocols mpls interface ge-1/2/2.13
set protocols ospf area 0.0.0.0 interface
lo0.3 passive
set protocols ospf area 0.0.0.0 interface
ge-1/2/0.6
set protocols ospf area 0.0.0.0 interface
ge-1/2/1.9
set protocols ospf area 0.0.0.0 interface
ge-1/2/2.13
set protocols ldp interface ge-1/2/0.6
set protocols ldp interface ge-1/2/1.9
set protocols ldp interface ge-1/2/2.13
set protocols ldp p2mp
set routing-options router-id 172.16.1.3

Device R4

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set interfaces ge-1/2/0 unit 10 family inet
address 10.1.1.10/30
set interfaces ge-1/2/0 unit 10 family mpls
set interfaces ge-1/2/1 unit 17 family inet
address 10.1.1.17/30
set interfaces ge-1/2/1 unit 17 family mpls
set interfaces vt-1/2/0 unit 4 family inet
set interfaces lo0 unit 4 family inet address
172.16.1.4/32
set interfaces lo0 unit 104 family inet address
172.16.100.1/32
set protocols rsvp interface all aggregate
set protocols mpls interface all
set protocols mpls interface ge-1/2/0.10
set protocols bgp group ibgp type internal
set protocols bgp group ibgp local-address
172.16.1.4
set protocols bgp group ibgp family inet-vpn
unicast
set protocols bgp group ibgp family inet-vpn
any
set protocols bgp group ibgp family inet-mvpn
signaling damping
set protocols bgp group ibgp neighbor 172.16.1.2
import dampPolicy
set protocols bgp group ibgp neighbor 172.16.1.5
set protocols ospf traffic-engineering
set protocols ospf area 0.0.0.0 interface
all
set protocols ospf area 0.0.0.0 interface
lo0.4 passive
set protocols ospf area 0.0.0.0 interface
ge-1/2/0.10
set protocols ldp interface ge-1/2/0.10
set protocols ldp p2mp
set policy-options policy-statement dampPolicy
term term1 from family inet-mvpn
set policy-options policy-statement dampPolicy
term term1 from nlri-route-type 3
set policy-options policy-statement dampPolicy
term term1 from nlri-route-type 4
set policy-options policy-statement dampPolicy
term term1 from nlri-route-type 5
set policy-options policy-statement dampPolicy
term term1 then accept
set policy-options policy-statement dampPolicy
then damping no-damp
set policy-options policy-statement dampPolicy
then accept
set policy-options policy-statement parent_vpn_routes
from protocol bgp
set policy-options policy-statement parent_vpn_routes
then accept
set policy-options damping no-damp disable
set routing-instances vpn-1 instance-type
vrf
set routing-instances vpn-1 interface vt-1/2/0.4
set routing-instances vpn-1 interface ge-1/2/1.17
set routing-instances vpn-1 interface lo0.104
set routing-instances vpn-1 route-distinguisher
100:100
set routing-instances vpn-1 vrf-target target:1:1
set routing-instances vpn-1 protocols ospf
export parent_vpn_routes
set routing-instances vpn-1 protocols ospf
area 0.0.0.0 interface lo0.104 passive
set routing-instances vpn-1 protocols ospf
area 0.0.0.0 interface ge-1/2/1.17
set routing-instances vpn-1 protocols pim
rp static address 172.16.100.1
set routing-instances vpn-1 protocols pim
interface ge-1/2/1.17 mode sparse
set routing-instances vpn-1 protocols mvpn
set routing-options router-id 172.16.1.4
set routing-options autonomous-system 64501

Device R5

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set interfaces ge-1/2/0 unit 14 family inet
address 10.1.1.14/30
set interfaces ge-1/2/0 unit 14 family mpls
set interfaces ge-1/2/1 unit 21 family inet
address 10.1.1.21/30
set interfaces ge-1/2/1 unit 21 family mpls
set interfaces vt-1/2/0 unit 5 family inet
set interfaces lo0 unit 5 family inet address
172.16.1.5/32
set interfaces lo0 unit 105 family inet address
172.16.100.5/32
set protocols mpls interface ge-1/2/0.14
set protocols bgp group ibgp type internal
set protocols bgp group ibgp local-address
172.16.1.5
set protocols bgp group ibgp family inet-vpn
any
set protocols bgp group ibgp family inet-mvpn
signaling
set protocols bgp group ibgp neighbor 172.16.1.2
set protocols bgp group ibgp neighbor 172.16.1.4
set protocols ospf area 0.0.0.0 interface
lo0.5 passive
set protocols ospf area 0.0.0.0 interface
ge-1/2/0.14
set protocols ldp interface ge-1/2/0.14
set protocols ldp p2mp
set policy-options policy-statement parent_vpn_routes
from protocol bgp
set policy-options policy-statement parent_vpn_routes
then accept
set routing-instances vpn-1 instance-type
vrf
set routing-instances vpn-1 interface vt-1/2/0.5
set routing-instances vpn-1 interface ge-1/2/1.21
set routing-instances vpn-1 interface lo0.105
set routing-instances vpn-1 route-distinguisher
100:100
set routing-instances vpn-1 vrf-target target:1:1
set routing-instances vpn-1 protocols ospf
export parent_vpn_routes
set routing-instances vpn-1 protocols ospf
area 0.0.0.0 interface lo0.105 passive
set routing-instances vpn-1 protocols ospf
area 0.0.0.0 interface ge-1/2/1.21
set routing-instances vpn-1 protocols pim
rp static address 172.16.100.2
set routing-instances vpn-1 protocols pim
interface ge-1/2/1.21 mode sparse
set routing-instances vpn-1 protocols mvpn
set routing-options router-id 172.16.1.5
set routing-options autonomous-system 1001

Device R6

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set interfaces ge-1/2/0 unit 18 family inet
address 10.1.1.18/30
set interfaces ge-1/2/0 unit 18 family mpls
set interfaces lo0 unit 6 family inet address
172.16.1.6/32
set protocols sap listen 233.1.1.1
set protocols ospf area 0.0.0.0 interface
lo0.6 passive
set protocols ospf area 0.0.0.0 interface
ge-1/2/0.18
set protocols pim rp static address 172.16.100.2
set protocols pim interface all
set routing-options router-id 172.16.1.6

Device R7

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set interfaces ge-1/2/0 unit 22 family inet
address 10.1.1.22/30
set interfaces ge-1/2/0 unit 22 family mpls
set interfaces lo0 unit 7 family inet address
172.16.1.7/32
set protocols ospf area 0.0.0.0 interface
lo0.7 passive
set protocols ospf area 0.0.0.0 interface
ge-1/2/0.22
set protocols pim rp static address 172.16.100.2
set protocols pim interface all
set routing-options router-id 172.16.1.7

Configuring Device R4

Step-by-Step Procedure

To configure Device R4:

Configure the interfaces.

[edit interfaces]
user@R4# set ge-1/2/0 unit 10 family inet address 10.1.1.10/30
user@R4# set ge-1/2/0 unit 10 family mpls

user@R4# set ge-1/2/1 unit 17 family inet address 10.1.1.17/30
user@R4# set ge-1/2/1 unit 17 family mpls

user@R4# set vt-1/2/0 unit 4 family inet

user@R4# set lo0 unit 4 family inet address 172.16.1.4/32
user@R4# set lo0 unit 104 family inet address 172.16.100.4/32
Configure MPLS and the signaling protocols on the interfaces.

[edit protocols]
user@R4# set mpls interface all
user@R4# set mpls interface ge-1/2/0.10
user@R4# set rsvp interface all aggregate
user@R4# set ldp interface ge-1/2/0.10
user@R4# set ldp p2mp
Configure BGP.
The BGP configuration enables BGP route flap damping for the inet-mvpn address family. The BGP configuration also imports into the routing table the routing policy called dampPolicy. This policy is applied to neighbor PE Device R2.

[edit protocols bgp group ibgp]
user@R4# set type internal
user@R4# set local-address 172.16.1.4
user@R4# set family inet-vpn unicast
user@R4# set family inet-vpn any
user@R4# set family inet-mvpn signaling damping
user@R4# set neighbor 172.16.1.2 import dampPolicy
user@R4# set neighbor 172.16.1.5
Configure an interior gateway protocol.

[edit protocols ospf]
user@R4# set traffic-engineering

[edit protocols ospf area 0.0.0.0]
user@R4# set interface all
user@R4# set interface lo0.4 passive
user@R4# set interface ge-1/2/0.10
Configure a damping policy that uses the nlri-route-type match condition to damp only MVPN route types 3, 4, and 5.

[edit policy-options policy-statement dampPolicy term term1]
user@R4# set from family inet-mvpn
user@R4# set from nlri-route-type 3
user@R4# set from nlri-route-type 4
user@R4# set from nlri-route-type 5
user@R4# set then accept
Configure the damping policy to disable BGP route flap damping.
The no-damp policy (damping no-damp disable) causes any damping state that is present in the routing table to be deleted. The then damping no-damp statement applies the no-damp policy as an action and has no from match conditions. Therefore, all routes that are not matched by term1 are matched by this term, with the result that all other MVPN route types are not damped.

[edit policy-options policy-statement dampPolicy]
user@R4# set then damping no-damp
user@R4# set then accept

[edit policy-options]
user@R4# set damping no-damp disable
Configure the parent_vpn_routes to accept all other BGP routes that are not from the inet-mvpn address family.
This policy is applied as an OSPF export policy in the routing instance.

[edit policy-options policy-statement parent_vpn_routes]
user@R4# set from protocol bgp
user@R4# set then accept
Configure the VPN routing and forwarding (VRF) instance.

[edit routing-instances vpn-1]
user@R4# set instance-type vrf
user@R4# set interface vt-1/2/0.4
user@R4# set interface ge-1/2/1.17
user@R4# set interface lo0.104
user@R4# set route-distinguisher 100:100
user@R4# set vrf-target target:1:1
user@R4# set protocols ospf export parent_vpn_routes
user@R4# set protocols ospf area 0.0.0.0 interface lo0.104 passive
user@R4# set protocols ospf area 0.0.0.0 interface ge-1/2/1.17
user@R4# set protocols pim rp static address 172.16.100.2
user@R4# set protocols pim interface ge-1/2/1.17 mode sparse
user@R4# set protocols mvpn
Configure the router ID and the autonomous system (AS) number.

[edit routing-options]
user@R4# set router-id 172.16.1.4
user@R4# set autonomous-system 1001
If you are done configuring the device, commit the configuration.

user@R4# commit

Results

From configuration mode, confirm your configuration by entering the show interfaces, show protocols, show policy-options, show routing-instances, and show routing-options commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

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user@R4# show interfaces
ge-1/2/0 {
unit 10 {
family inet {
address 10.1.1.10/30;
}
family mpls;
}
}
ge-1/2/1 {
unit 17 {
family inet {
address 10.1.1.17/30;
}
family mpls;
}
}
vt-1/2/0 {
unit 4 {
family inet;
}
}
lo0 {
unit 4 {
family inet {
address 172.16.1.4/32;
}
}
unit 104 {
family inet {
address 172.16.100.4/32;
}
}
}

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user@R4# show protocols
rsvp {
interface all {
aggregate;
}
}
mpls {
interface all;
interface ge-1/2/0.10;
}
bgp {
group ibgp {
type internal;
local-address 172.16.1.4;
family inet-vpn {
unicast;
any;
}
family inet-mvpn {
signaling {
damping;
}
}
neighbor 172.16.1.2 {
import dampPolicy;
}
neighbor 172.16.1.5;
}
}
ospf {
traffic-engineering;
area 0.0.0.0 {
interface all;
interface lo0.4 {
passive;
}
interface ge-1/2/0.10;
}
}
ldp {
interface ge-1/2/0.10;
p2mp;
}

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user@R4# show policy-options
policy-statement dampPolicy {
term term1 {
from {
family inet-mvpn;
nlri-route-type [ 3 4 5 ];
}
then accept;
}
then {
damping no-damp;
accept;
}
}
policy-statement parent_vpn_routes {
from protocol bgp;
then accept;
}
damping no-damp {
disable;
}

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user@R4# show routing-instances
vpn-1 {
instance-type vrf;
interface vt-1/2/0.4;
interface ge-1/2/1.17;
interface lo0.104;
route-distinguisher 100:100;
vrf-target target:1:1;
protocols {
ospf {
export parent_vpn_routes;
area 0.0.0.0 {
interface lo0.104 {
passive;
}
interface ge-1/2/1.17;
}
}
pim {
rp {
static {
address 172.16.100.2;
}
}
interface ge-1/2/1.17 {
mode sparse;
}
}
mvpn;
}
}

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user@R4# show routing-optons
router-id 172.16.1.4;
autonomous-system 1001;

Verification

Confirm that the configuration is working properly.

Verifying That Route Flap Damping Is Disabled

Purpose

Verify the presence of the no-damp policy, which disables damping for MVPN route types other than 3, 4, and 5.

Action

From operational mode, enter the show policy damping command.

user@R4> show policy damping

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Default damping information:
  Halflife: 15 minutes
  Reuse merit: 750 Suppress/cutoff merit: 3000
  Maximum suppress time: 60 minutes
  Computed values:
    Merit ceiling: 12110
    Maximum decay: 6193
Damping information for "no-damp":
  Damping disabled

Meaning

The output shows that the default damping parameters are in effect and that the no-damp policy is also in effect for the specified route types.

Verifying Route Flap Damping

Purpose

Check whether BGP routes have been damped.

Action

From operational mode, enter the show bgp summary command.

user@R4> show bgp summary

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Groups: 1 Peers: 2 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
bgp.l3vpn.0          
                       6          6          0          0          0          0
bgp.l3vpn.2          
                       0          0          0          0          0          0
bgp.mvpn.0           
                       2          2          0          0          0          0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Accepted/Damped...
172.16.1.2                1001       3159       3155       0       0    23:43:47 Establ
  bgp.l3vpn.0: 3/3/3/0
  bgp.l3vpn.2: 0/0/0/0
  bgp.mvpn.0: 1/1/1/0
  vpn-1.inet.0: 3/3/3/0
  vpn-1.mvpn.0: 1/1/1/0
172.16.1.5                1001       3157       3154       0       0    23:43:40 Establ
  bgp.l3vpn.0: 3/3/3/0
  bgp.l3vpn.2: 0/0/0/0
  bgp.mvpn.0: 1/1/1/0
  vpn-1.inet.0: 3/3/3/0
  vpn-1.mvpn.0: 1/1/1/0

Meaning

The Damp State field shows that zero routes in the bgp.mvpn.0 routing table have been damped. Further down, the last number in the State field shows that zero routes have been damped for BGP peer 172.16.1.2.

ON THIS PAGE

Examples: Configuring BGP Flap Damping

Understanding Damping Parameters

See also

Example: Configuring BGP Route Flap Damping Parameters

Requirements

Overview

Configuration

CLI Quick Configuration

Device R1

Device R2

Device R3

Step-by-Step Procedure

Results

Verification

Causing Some Routes to Flap

Purpose

Action

Meaning

Checking the Route Flaps

Purpose

Action

Meaning

Verifying Route Flap Damping

Purpose

Action

Meaning

Displaying the Details of a Damped Route

Purpose

Action

Meaning

Verifying That Default Damping Parameters Are in Effect

Purpose

Action

Meaning

Filtering the Damping Information

Purpose

Action

Meaning

See also

Example: Configuring BGP Route Flap Damping Based on the MBGP MVPN Address Family

Requirements

Overview

Configuration

CLI Quick Configuration

Device R1

Device R2

Device R3

Device R4

Device R5

Device R6

Device R7

Configuring Device R4

Step-by-Step Procedure

Results

Verification

Verifying That Route Flap Damping Is Disabled

Purpose

Action

Meaning

Verifying Route Flap Damping

Purpose

Action

Meaning

See also

Related Documentation