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connectlife
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Router Reflector Scenario

Thu Oct 13, 2022 9:14 am

Hello, I'm setting up a reflector router with FRR in the lab.
I have a Mikrotik ROS 7.6rc2 peering eBGP with a provider, the provider sends me about 145,000 routes. On the Mikrotik I have configured an iBGP peer towards the Route Reflector, the routes are then correctly propagated to the router reflector. The problem is that the router reflector sends the routes back to the mikrotik and I find myself on the routing table of the double routes, the routes received by the reflector are obviously disabled because they have a weight of 200 while the eBGP route is the active one. I remember that with ROS6 iBGP routes that were double or in any case non-preferential compared to an eBGP route were automatically withdrawn.

What am I forgetting?

Theoretically RouterOS should discard the paths received from the Reflector which have as Originator ID itself or am I wrong?
 
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nichky
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Re: Router Reflector Scenario

Thu Oct 13, 2022 2:39 pm

from MT wiki:
Also note that next-hop is not changed on route reflection, except when it's set in the filter.

so u need routing/filter/ rules
 
connectlife
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Re: Router Reflector Scenario

Thu Oct 13, 2022 4:31 pm

from MT wiki:
Also note that next-hop is not changed on route reflection, except when it's set in the filter.

so u need routing/filter/ rules
Hi Nicky, it's not about the next hop .. here's what the support replied:

Thank you for the report, It is a known problem and will be fixed in the future.

Unfortunately there is no filter capable of discarding a route via Originator ID, see: https://help.mikrotik.com/docs/display/ ... nd+Filters
 
Dude2048
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Re: Router Reflector Scenario

Thu Oct 13, 2022 10:10 pm

Maybe construct a deny filter for the corresponding iBGP connection so that it won't advertise the routes back to the originator. For the time being this seems to me the only solution.
 
connectlife
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Re: Router Reflector Scenario

Fri Oct 14, 2022 12:28 am

do you mean some filters on the reflector router side?

because I thought of creating a filter on the mikrotik rr to discard all the prefixes that have as originator ID itself .. unfortunately there is no expression to detect the originator ID from the RouterOS filters ..

maybe i should look if i can do something about FRR ..
 
Dude2048
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Re: Router Reflector Scenario

Fri Oct 14, 2022 10:53 am

On the RR itself since the last filter rule is a deny all. In that way it won't be re-advertised to the originator.

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