tuning of bgp dampening

[pacquaviva]

Hi,

If someone knows what are the parameters normally used in bgp dampening for a perfect work.

I thought that they can be:

half-life: 10 minutes

reuse: 750

suppress-value:2000

max-suppress-time: 40 minutes

Are those correct or I have to review all?

Thank you.

Regards.

Paolo

[vladrac-ccna]

Hello Paolo,

This parameters will depend on your network and how frequently you see the flappings.

There are some default values though:

half-life-time

Defines the amount of time in minutes after which a penalty is reduced by half. Valid values are 10 - 45 minutes. Default: 15 minutes.

reuse-value

Defines the accumulated penalty amount at which the route is re-advertised. Valid values are 500 - 20000.

Default: 750.

suppress-value

Defines the accumulated penalty amount at which the route is suppressed. Valid values are 500 - 20000.

Default: 2000.

maximum-suppress-time

Defines the maximum time in minutes that a route is suppressed. Valid values are 1 - 90.

Default: 60 or 4 times the value of half-life time.

You''ll need to take a better look on the routes you are tracking and tune the values.

Check the following link for such a study:

http://ftp.iasi.roedu.net/mirrors/ftp.ripe.net/presentations/ripe-m25-tbarber-bgp-damp.html

HTH,

please remember to rate helpful posts.

Vlad

[pacquaviva]

Hi,

I would like to know how to protect important routes from dampening.

If I put into a route map a match with an access-list that permit a default route and after this I create a bgp dampening rule.

I would like to know if this works (don't dampen the dafault route).

Thank you

regards.

Paolo

[andrew.gristina]

NANOG doesn't really recommend dampening anymore.

Same with RIPE:

http://www.ripe.net/ripe/docs/ripe-378.html

If this is for a test, go ahead, but if this is operational, I would find an operators group or other suitable reference.

Most of the email/news group feeds that encourage route dampening are from the 90s and have been superceded by the current recommendations.

[vladrac-ccna]

Good point from Andrew.

I usually only give straight tech advises, about what is asked.

In this case, I would answer, yes, you can specify specifics routes on the route-map to dampening the routes you want.

Vlad