Date: Sat, 29 Apr 2023 22:44:02 +0100 From: "Alexander Chernikov" <melifaro@FreeBSD.org> To: freebsd-net@freebsd.org Subject: Re: Duplicates IP packets when using CARP and ECMP routes. Message-ID: <3f3507f6-fc53-444b-8730-d61143ba3c1e@app.fastmail.com> In-Reply-To: <e57135b2-90a2-b71e-8a7d-b80a2f638b9f@normandie-univ.fr> References: <e57135b2-90a2-b71e-8a7d-b80a2f638b9f@normandie-univ.fr>
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[-- Attachment #1 --]
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
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<!DOCTYPE html><html><head><title></title><style type="text/css">p.MsoNormal,p.MsoNoSpacing{margin:0}</style></head><body><div><br></div><div><br></div><div>On Sat, 29 Apr 2023, at 11:01 AM, Arnaud Houdelette-Langlois wrote:<br></div><blockquote type="cite" id="qt" style=""><p>Hi.<br></p><p>We got a freebsd router with both ospf/bpg and multipath routes
(ECMP) (using the new bird2 with netlink) .<br></p><p>The router got an interface with carp enabled on it (gateway for
admin vlan).<br></p><p>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)<br></p><p>Using a simple alias instead of carp solve the problem. Is this a
known problem, or should I fill a PR ?<br></p></blockquote><div>No, that’s not a known problem. <br></div><div>Please do open the PR with details.</div><blockquote type="cite" id="qt" style=""><pre class="qt-moz-signature" cols="72">--
Arnaud Houdelette-Langlois
Administrateur des infrastructures systèmes et réseaux
Normandie Université
+33 2 31 56 69 54<br></pre><div id="qt-grammalecte_menu_main_button_shadow_host" style="width:0px;height:0px;"><br></div></blockquote><div><br></div><div id="sig132921232"><div class="signature">/Alexander<br></div></div></body></html>
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