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mikhan
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Joined: Mon Aug 16, 2021 5:56 am

How to use "input accept communities" in BGP?

Fri Jun 24, 2022 5:21 pm

https://help.mikrotik.com/docs/display/ROS/BGP
input.accept-comunities (string; Default: ) A quick way to filter incoming updates with specific communities. It allows filtering incoming messages directly before they are even parsed and stored in memory, that way significantly reducing memory usage. Regular input filter chain can only reject prefixes which means that it will still eat memory and will be visible in /routing route table as "not active, filtered". Changes to be applied required session refresh.

I use a service that provides a bunch of bgp communities and I want to filter some of them.
E.g. I need 65444:700 and 65444:710

so I add:
/routing filter community-list
add communities=65444:710,65444:700 disabled=no list=some_list
I edit my bgp connection to enable input.accept-communities
/routing bgp connection
add as=*** disabled=no hold-time=4m input.accept-communities=some_list \
    .filter=bgp_in keepalive-time=1m listen=yes local.address=*** .role=\
    ebgp multihop=yes name=some_bgp output.filter-chain=discard \
    remote.address=*** .as=65444 router-id=*** \
    routing-table=main
filter to enable gw to routes:
/routing filter rule
add chain=bgp_in disabled=no rule="set gw some_gw; accept"

But nothing happens, I still receive all the communities.
It works only f I use filtering like below:
/routing filter rule
add chain=bgp_in disabled=no rule="if ( bgp-communities equal 65444:700 || bg\
    p-communities equal 65444:710) {set gw some_gw; accept}"
But it's a waste of resources...
 
mikhan
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Joined: Mon Aug 16, 2021 5:56 am

Re: How to use "input accept communities" in BGP?

Thu Jul 21, 2022 12:31 pm

anyone?
 
alexkerch
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Joined: Wed May 20, 2020 5:14 pm

Re: How to use "input accept communities" in BGP?

Sun Sep 25, 2022 9:30 pm

Please tell me, were you able to solve your problem and in what way?
 
mikhan
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Posts: 5
Joined: Mon Aug 16, 2021 5:56 am

Re: How to use "input accept communities" in BGP?

Tue Sep 27, 2022 1:21 pm

No. They say it's a bug in routeros.

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