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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On Sat, 29 Apr 2023, at 11:01 AM, Arnaud Houdelette-Langlois wrote:
> Hi.
>=20
> We got a freebsd router with both ospf/bpg and multipath routes (ECMP)=
(using the new bird2 with netlink) .
>=20
> The router got an interface with carp enabled on it (gateway for admin=
vlan).
>=20
> Packets received on the carp address gets routed on all known routes t=
owards destination. Thus, the destination host receives duplicates ip pa=
ckets. (which disrupts most udp based protocols)
>=20
> Using a simple alias instead of carp solve the problem. Is this a know=
n problem, or should I fill a PR ?
>=20
No, that=E2=80=99s not a known problem.=20
Please do open the PR with details.
> --=20
> Arnaud Houdelette-Langlois
> Administrateur des infrastructures syst=C3=A8mes et r=C3=A9seaux
> Normandie Universit=C3=A9
> +33 2 31 56 69 54
>=20
/Alexander
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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,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-Langl=
ois wrote:<br></div><blockquote type=3D"cite" id=3D"qt" style=3D""><p>Hi=
.<br></p><p>We got a freebsd router with both ospf/bpg and multipath rou=
tes
(ECMP) (using the new bird2 with netlink) .<br></p><p>The router g=
ot an interface with carp enabled on it (gateway for
admin vlan).<br></p><p>Packets received on the carp address gets r=
outed on all known
routes towards destination. Thus, the destination host receives
duplicates ip packets. (which disrupts most udp based protocols)<b=
r></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=E2=80=99s not a known problem. <br></div><div>Please do open=
the PR with details.</div><blockquote type=3D"cite" id=3D"qt" style=3D"=
"><pre class=3D"qt-moz-signature" cols=3D"72">--=20
Arnaud Houdelette-Langlois
Administrateur des infrastructures syst=C3=A8mes et r=C3=A9seaux
Normandie Universit=C3=A9
+33 2 31 56 69 54<br></pre><div id=3D"qt-grammalecte_menu_main_button_sh=
adow_host" style=3D"width:0px;height:0px;"><br></div></blockquote><div><=
br></div><div id=3D"sig132921232"><div class=3D"signature">/Alexander<br=
></div></div></body></html>
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