From owner-svn-src-all@freebsd.org Sun Oct 30 09:45:33 2016 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id D6F15C258E1; Sun, 30 Oct 2016 09:45:33 +0000 (UTC) (envelope-from koobs.freebsd@gmail.com) Received: from mail-pf0-x22f.google.com (mail-pf0-x22f.google.com [IPv6:2607:f8b0:400e:c00::22f]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 9E0F5C7; Sun, 30 Oct 2016 09:45:33 +0000 (UTC) (envelope-from koobs.freebsd@gmail.com) Received: by mail-pf0-x22f.google.com with SMTP id 197so61091936pfu.0; Sun, 30 Oct 2016 02:45:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:reply-to:subject:to:references:from:cc:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=3aATrhi+s1cy+t8zYwsBBuWiTDchdvYlDhJHr5+FEgQ=; b=0rtcfC5IpO0vBVg+/wET87Xscsi2zT1P9btd6Lq6sK/xMCJFKkusReuhIa/YTcb9DR REBRH4CCIIrlLG3kPdZJhDt4mnFVxjZ1BpQ08Ogz6EexFDzadTLRrYN06eMhVW+NcOo0 A+lE2FVRF0Ahb6MuA7TBrtPoUPpeaODiRwXUFmfSt2cS7DgfYSqHWEpm8ZwOKon1Mmj0 f+uN+m3n7N7otpwsB4ysjAnsXnCOhCiuqG/RP6hrygpZsJWZDY5m43qdDzGm+0F7SxSl QSGOjOUTHMzccIOjYrI3Oi1l9mqAcJJ6sj05+DhqlaTvYW4YrsymolWW3UdpcgyJgLhl 3YDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:sender:reply-to:subject:to:references:from:cc :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=3aATrhi+s1cy+t8zYwsBBuWiTDchdvYlDhJHr5+FEgQ=; b=NXjnxgN5nd+vz8tSzCnyrLfhwP3oXy/vBxQh3XefTZivx+J+A5lNRy9SzMsrtK7ftE L6I5KCZ/nOiCyDykHTsv0xa//spE1SjO0ge9WXzaEdsqFEw4Qdk2tvl8+jVckppy9Rwl DZ1uGJY5Oo8HEwyHjW4kDPzRXpXHaKP8T+d4ZqUseJ2ktV4VcHT2U0JJSN8IJ2b10vn0 vPhytP9DiWGd6BNPzwAaLFn5BoOxdJA9qEzCJves6GjeCIRyU9CHdS/8GsdNONQDQ6la qwTBjr/s9XUaA450ze64h56JpYWPzKfld72g+D3nBAR1vyjnblqndOt1bcxLDTZKZIY4 tPOQ== X-Gm-Message-State: ABUngvfetHtfSIsrJYL4+Y8csoMI1kiOthxZzyB3S0r6Vnu6NGQuY8UySH03uTfiiwBUZQ== X-Received: by 10.98.18.220 with SMTP id 89mr40193122pfs.71.1477820733008; Sun, 30 Oct 2016 02:45:33 -0700 (PDT) Received: from ?IPv6:2001:44b8:31ae:7b01:bcc5:61de:d926:8238? (2001-44b8-31ae-7b01-bcc5-61de-d926-8238.static.ipv6.internode.on.net. [2001:44b8:31ae:7b01:bcc5:61de:d926:8238]) by smtp.gmail.com with ESMTPSA id l187sm29397176pfc.0.2016.10.30.02.45.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 30 Oct 2016 02:45:32 -0700 (PDT) Sender: Kubilay Kocak Reply-To: koobs@FreeBSD.org Subject: Re: svn commit: r306577 - head/sys/netinet To: Eric van Gyzen , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org References: <201610020142.u921gjsJ016528@repo.freebsd.org> From: Kubilay Kocak Cc: Steven Hartland , Gleb Smirnoff Message-ID: <46cdc5d8-75ee-16f6-ee9d-d9c14cb5098e@FreeBSD.org> Date: Sun, 30 Oct 2016 20:44:13 +1100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Thunderbird/51.0a2 MIME-Version: 1.0 In-Reply-To: <201610020142.u921gjsJ016528@repo.freebsd.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-AU Content-Transfer-Encoding: 7bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 30 Oct 2016 09:45:33 -0000 On 2/10/2016 12:42 PM, Eric van Gyzen wrote: > Author: vangyzen Date: Sun Oct 2 01:42:45 2016 New Revision: 306577 > URL: https://svnweb.freebsd.org/changeset/base/306577 > > Log: Add GARP retransmit capability > > A single gratuitous ARP (GARP) is always transmitted when an IPv4 > address is added to an interface, and that is usually sufficient. > However, in some circumstances, such as when a shared address is > passed between cluster nodes, this single GARP may occasionally be > dropped or lost. This can lead to neighbors on the network link > working with a stale ARP cache and sending packets destined for that > address to the node that previously owned the address, which may not > respond. > > To avoid this situation, GARP retransmissions can be enabled by > setting the net.link.ether.inet.garp_rexmit_count sysctl to a value > greater than zero. The setting represents the maximum number of > retransmissions. The interval between retransmissions is calculated > using an exponential backoff algorithm, doubling each time, so the > retransmission intervals are: {1, 2, 4, 8, 16, ...} (seconds). > > Due to the exponential backoff algorithm used for the interval > between GARP retransmissions, the maximum number of retransmissions > is limited to 16 for sanity. This limit corresponds to a maximum > interval between retransmissions of 2^16 seconds ~= 18 hours. > Increasing this limit is possible, but sending out GARPs spaced days > apart would be of little use. > Thanks for this David & Eric I presume this is (or would be) quite complementary to D4111 [1] (Gratuitous ARP's for lagg(4) failover) when it lands? I'm thinking particularly given the various states upstream switch ports can have during topology changes. [1] https://reviews.freebsd.org/D4111 ./koobs