Re: Duplicates IP packets when using CARP and ECMP routes.

From: Arnaud Houdelette-Langlois <arnaud.houdelette_at_normandie-univ.fr>
Date: Mon, 01 May 2023 14:08:18 UTC
Thanks for the info.

I opened the PR : https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=271168


Arnaud Houdelette-Langlois
Administrateur des infrastructures systèmes et réseaux
Normandie Université
+33 2 31 56 69 54

Le 29/04/2023 à 23:44, Alexander Chernikov a écrit :
>
>
> On Sat, 29 Apr 2023, at 11:01 AM, Arnaud Houdelette-Langlois wrote:
>>
>> Hi.
>>
>> We got a freebsd router with both ospf/bpg and multipath routes 
>> (ECMP) (using the new bird2 with netlink) .
>>
>> The router got an interface with carp enabled on it (gateway for 
>> admin vlan).
>>
>> Packets received on the carp address gets routed on all known routes 
>> towards destination. Thus, the destination host receives duplicates 
>> ip packets. (which disrupts most udp based protocols)
>>
>> Using a simple alias instead of carp solve the problem. Is this a 
>> known problem, or should I fill a PR ?
>>
> No, that’s not a known problem.
> Please do open the PR with details.
>> -- 
>> Arnaud Houdelette-Langlois
>> Administrateur des infrastructures systèmes et réseaux
>> Normandie Université
>> +33 2 31 56 69 54
>>
>
> /Alexander