BGP Route Dampening - 1.2.5

General questions
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1

I’m running VyOS 1.2.5 and need to configure BGP route dampening. The documentation for version 1.2.X doesn’t include any commands but 1.3 and 1.4 does. Nonetheless, the configuration commands to enable dampening are accepted by the router in 1.2.5

set protocols bgp [asn] parameters dampening [options]

However, when I test the feature nothing happens. Is this functionality available in this version? If not, which version was it introduced in?

Thanks

Andres

2

I see that feature present even in the oldest releases.
Can you provide your configuration and describe how do you check it?
Do you really need this?

3

The commands entered are:

set protocols bgp 65530 parameters dampening half-life ‘15’
set protocols bgp 65530 parameters dampening max-suppress-time ‘60’
set protocols bgp 65530 parameters dampening re-use ‘750’
set protocols bgp 65530 parameters dampening start-suppress-time ‘2000’

And I just bounced the link multiple times to the BGP peer to simulate the flapping of the routes. However, I can’t see any information about penalties applied to the routes or those been withdrawn after reaching the “start-suppress-time” value (which they should after multiple bounces).

We recently had a flapping of links to this router for about 10 minutes which affected the service so we need dampening to mitigate the effects of this type of issues.

4

Any other help that anyone can provide? I still can’t get route dampening working and the config seems to be OK

5

Update: I was able to find the problem. The issue was that I was simulating the flapping by disconnecting and connecting the link which effectively kills the BGP session.
Route dampening works when the flapping is in the advertisement of the routes (prefixes being withdrawn and re-advertised) but always keeping the BGP session active.
Once I simulated this behaviour by flapping links upstream or manually withdrawing routes, then dampening worked as expected.

6

I am pretty keen to know and would really appreciate; how did you simulate the route flapping?

7

You can go into the upstream router that connects to the VyOS router and either remove the “redistribute” statement or the “network” statement under the BGP configuraiton and add it again many times.

Another way is if the upstream router, in turn, connects to another router, kill and restore the link to that second router so that will effectively make the adjacent router to withdraw routes downstream

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8

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