Cisco access-lists ???

Danny McPherson danny at genuity.net
Sat Jun 28 02:35:17 UTC 1997


something like this ("in cisco parlance" :-) should do the trick:

router bgp 65534
 bgp dampening route-map damp
!
access-list 101 permit ip any 255.255.240.0 0.0.15.255
access-list 102 permit ip any any
!
route-map damp permit 10
 match ip address 101
 set dampening 30 750 2000 90
!
route-map damp permit 20
 match ip address 102
 set dampening 15 750 2000 60

you can see the effects from the output below.  in short, i've tightened the 
thresholds on prefixes longer than /19.

lab2-7507#sh ip bgp fla
BGP table version is 91081, local router ID is 207.240.2.3
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          From            Flaps Duration Reuse    Path
*d 215.1.0.0        207.240.2.2     4     00:02:35 00:58:30 65533
*d 215.1.0.0/20     207.240.2.2     4     00:02:35 00:58:30 65533
*d 215.1.0.0/16     207.240.2.2     4     00:02:35 00:28:40 65533
lab2-7507#

we're currently not dampening based on prefix length yet, although we are 
experimenting with it.

-danny

> 
> The 'discussion' of Jack's report seems to have overwhelmed an actual
> operational question.  I am shocked and surprised.
> 
> In cisco parlance, such an entry might be
> 
>     access-list 142 deny ip any  255.255.255.128 0.0.0.127
> 
> which blocks any prefix longer than a /24.
> 
> As to how to express the dampening in the report you mention, could someone
> who has it actually installed (come on RV, SD, ...) and debugged please
> post?  I have exceeded my error quota for the day.  Thanks.
> 
> randy





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