From nobody Sat Apr 29 10:01:38 2023 X-Original-To: freebsd-net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4Q7lPT4PwSz48mps for ; Sat, 29 Apr 2023 10:01:49 +0000 (UTC) (envelope-from arnaud.houdelette@normandie-univ.fr) Received: from usmtp2.unr-runn.fr (usmtp2.unr-runn.fr [IPv6:2001:660:7404:810::57]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4Q7lPR2bCmz3lj6 for ; Sat, 29 Apr 2023 10:01:47 +0000 (UTC) (envelope-from arnaud.houdelette@normandie-univ.fr) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=normandie-univ.fr header.s=20181002 header.b=QhPqJ0wP; spf=pass (mx1.freebsd.org: domain of arnaud.houdelette@normandie-univ.fr designates 2001:660:7404:810::57 as permitted sender) smtp.mailfrom=arnaud.houdelette@normandie-univ.fr; dmarc=none DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=normandie-univ.fr; s=20181002; h=Subject:From:To:MIME-Version:Date: Message-ID:Content-Type:Sender:Reply-To:Cc:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ZdVwF0nte4o/OmtM4oK3yExaxDQ8kl5Ry3UyO6n8Bsk=; b=QhPqJ0wPHnCy3tdNWIo7T4U9S /2zB5PsMeutnK+is+DVxCaVPEAGa25rCxwujAvQ5sdF/KccpwwNVnItuMsVpjUldawQCKyE8iewRt L0YD61viaNlGeFP9eY0muBnUZfi+rbCKcon49PwgD5Vs8guOWxSEjGBNo/HLHgrayAm8um2fizfql 1K3HJP8aYA86Km6nuor8k38PmZNgQSQfwxvDBhAkhCn2cMy3vFDHuWNZC2T8wJjmfHvrj69rOrrI0 nK4lzRec2uK8v9dnuOZ3H8mA20MXECJ0vtcLH0yGx0VpSPoptg9zikUHt9UbqZNRZEAZ4USA5jxFG BMT6n9sZA==; Received: from [2a01:e0a:3e0:9910:a136:53a9:aa92:da84] by usmtp2.unr-runn.fr with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1pshOd-000G8t-7d for freebsd-net@FreeBSD.org; Sat, 29 Apr 2023 12:01:39 +0200 Content-Type: multipart/alternative; boundary="------------ensIndlmXPF4K7cBMHjd0Qcg" Message-ID: Date: Sat, 29 Apr 2023 12:01:38 +0200 List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 To: freebsd-net@FreeBSD.org Content-Language: fr-FR, en-US From: Arnaud Houdelette-Langlois Subject: Duplicates IP packets when using CARP and ECMP routes. X-Spamd-Result: default: False [-3.50 / 15.00]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.999]; R_SPF_ALLOW(-0.20)[+ip6:2001:660:7404:810::/64]; R_DKIM_ALLOW(-0.20)[normandie-univ.fr:s=20181002]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; DKIM_TRACE(0.00)[normandie-univ.fr:+]; MLMMJ_DEST(0.00)[freebsd-net@FreeBSD.org]; MIME_TRACE(0.00)[0:+,1:+,2:~]; FROM_EQ_ENVFROM(0.00)[]; ASN(0.00)[asn:2200, ipnet:2001:660::/32, country:FR]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; DMARC_NA(0.00)[normandie-univ.fr]; MID_RHS_MATCH_FROM(0.00)[]; ARC_NA(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_HAS_DN(0.00)[]; TO_DN_NONE(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_TLS_ALL(0.00)[] X-Rspamd-Queue-Id: 4Q7lPR2bCmz3lj6 X-Spamd-Bar: --- X-ThisMailContainsUnwantedMimeParts: N This is a multi-part message in MIME format. --------------ensIndlmXPF4K7cBMHjd0Qcg Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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 ? -- Arnaud Houdelette-Langlois Administrateur des infrastructures systèmes et réseaux Normandie Université +33 2 31 56 69 54 --------------ensIndlmXPF4K7cBMHjd0Qcg Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit

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 ?

-- 
Arnaud Houdelette-Langlois
Administrateur des infrastructures systèmes et réseaux
Normandie Université
+33 2 31 56 69 54
--------------ensIndlmXPF4K7cBMHjd0Qcg--