BGP advertisements print doesn't match what's really published

dmayan · Fri Sep 20, 2019 4:05 pm

Hi,

When printing the advertisements to our FNA cluster, I can see this:

[dmayan.r@CORE-CACHES] > /rou bgp advertisements print FNA.IPv6 PEER PREFIX NEXTHOP AS-PATH ORIGIN LOCAL-PREF FNA.IPv6 2803:5440:ca::/64 2803:5440:fac... igp FNA.IPv6 2803:5440:face::/48 2803:5440:fac... igp FNA.IPv6 2803:5440:252::/48 2803:5440:fac... igp FNA.IPv6 2803:5440:ffff::/48 2803:5440:fac... igp FNA.IPv6 2803:5440:1::/48 2803:5440:fac... igp FNA.IPv6 2803:5440:cace::/48 2803:5440:fac... igp FNA.IPv6 2803:5440::/48 2803:5440:fac... igp FNA.IPv6 2803:5440:21::/48 2803:5440:fac... igp FNA.IPv6 2803:5440:ca::/48 2803:5440:fac... igp [dmayan.r@CORE-CACHES] >

But, if I capture the BGP traffic to the FNA cluster, and decode it with Wireshark, I see this as advertised:

Network layer reachability information (149 bytes) 2803:5440::/48 2803:5440:1::/48 2803:5440:2::/48 2803:5440:21::/48 2803:5440:ca::/48 2803:5440:ca::/64 2803:5440:100::/48 2803:5440:101::/48 2803:5440:112::/48 2803:5440:252::/48 2803:5440:4053::/48 2803:5440:4054::/48 2803:5440:4055::/48 2803:5440:4056::/48 2803:5440:4059::/48 2803:5440:4062::/48 2803:5440:4065::/48 2803:5440:4066::/48 2803:5440:cace::/48 2803:5440:face::/48 2803:5440:ffff::/48

所有在6.44.5 CCR1072

What's going on with this Mikrotik? It caused a lot of headaches doing troubleshooting for a problem that didn't exist.

And the IP routes "There are too many routes" bug on Winbox that you never solved.

Thanks

faisali · Thu Oct 03, 2019 5:01 am

Care to post the code of your filter ... i.e how are you controlling what you are advertising ?

dmayan · Thu Oct 03, 2019 5:03 pm

Care to post the code of your filter ... i.e how are you controlling what you are advertising ?

Hi Faisali,

Filters have nothing to do here. The problem is the router shows one thing on bgp/advertisements, and a is advertising a different thing, as the Wireshark capture on the BGP traffic shows.

thanks

sri2007 · Mon Oct 21, 2019 3:06 am

Hello, I've never seen that before, but just to be sure that your FNA is getting the prefixes, there is a way at the FNA partners portal where you can check all of the prefixes received at the Facebook servers (insights tab).

Also can you share your filters please? Have you tried by doing a resend action to those BGP peers? Is that related to IPv6 only or does it happens at IPv4 too?

dmayan · Mon Oct 21, 2019 3:58 pm

Hi SRI !!

Yes, the FNA are receiving the prefixes that I see in the packets capture. This became supicious when I began to see prefixes in the FNAs that were not in the advertisements. This is not summarization as the FNA receive more prefixes than the declared by ROS.

Here is the only filter affecting the FNA peer. It discards a loopback address.

国旗:X- disabled 0 chain=FNA_OUT prefix=xx.yy.22.254 prefix-length=32 invert-match=no action=discard set-bgp-prepend-path=""

I will check for IPv4 leaks and update the post.

Thanks!

Hello, I've never seen that before, but just to be sure that your FNA is getting the prefixes, there is a way at the FNA partners portal where you can check all of the prefixes received at the Facebook servers (insights tab).

Also can you share your filters please? Have you tried by doing a resend action to those BGP peers? Is that related to IPv6 only or does it happens at IPv4 too?

texmeshtexas · Wed Oct 14, 2020 2:05 am

Anyone find a solution to this.
Have same problem with a CCR1072 on 6.46.7
advertisements print show nothing to upstream peer and the upstream is receiving the prefixes and traffic is flowing as expected.

Strange thing is we have another CCR1072 peering to the same upstream on a different circuit and it shows everything properly.

BGP advertisements print doesn't match what's really published

BGP advertisements print doesn't match what's really published

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