We have a similar situation (RR + always-compare-MED off), and the BGP table
version keeps changing at 1K/min (http://performance.cn.net:2003/). I
suspect some
route meet the criteria of IDR-oscillation draft. But in real world, it's
very hard to pick
up the pattern depicted in the draft from a huge log of debug bgp output.
It's actually quite trivial to identify. Have a look at:
http://www.cisco.com/warp/public/770/fn12942.html
Juniper syntax would result in the same..
1. How many time do our operator really find and affected by the
problem depicted in draft-ietf-idr-route-oscillation-01.txt
I know of more than a few, and would bet that if additional folks
took the time to look, they'd realize it was occurring as well.
2. From my experience, most flapping seems to be oscillation route
which escaped the eBGP damping protection. And for this, we need
adjust damping parameters from RIPE 220 to make up.
Nope. Dampening doesn't resolve this because it occurs
intrA-domain.
3. Anyone see oscillation been magnified when injected
into RR (cluster structure) ?
Not sure I understand what you mean by "magnified"?
Have a look at the Cisco FN, it's useful in understanding and
identifying the problem.
-danny
danny@tcb.net disait :
> We have a similar situation (RR + always-compare-MED off), and the BGP table
> version keeps changing at 1K/min (http://performance.cn.net:2003/). I
> suspect some
> route meet the criteria of IDR-oscillation draft. But in real world, it's
> very hard to pick
> up the pattern depicted in the draft from a huge log of debug bgp output.
It's actually quite trivial to identify. Have a look at:
http://www.cisco.com/warp/public/770/fn12942.html
As Yu said, it is not so easy.
Most of the output in "show ip route bgp | include , 00:00" command match
flapping updates that are getting "dampening candidates" !!
Beside, you have to run the command on a router that might hit the
problem .... it depends a lot on your peering locations and partners.
If you run Cisco commands on wrong router, you would not see any
problem and may get in wrong conclusion !!
> 2. From my experience, most flapping seems to be oscillation route
> which escaped the eBGP damping protection. And for this, we need
> adjust damping parameters from RIPE 220 to make up.
Nope. Dampening doesn't resolve this because it occurs
intrA-domain.
Does not fix, but it would lower updates thus help to identify
update loops.
Vincent.