Date: Fri, 11 Nov 2005 17:15:19 +0300 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Bruce M Simpson <bms@spc.org> Cc: arch@FreeBSD.org Subject: Re: ARP request retransmitting Message-ID: <20051111141519.GE1647@cell.sick.ru> In-Reply-To: <20051111140926.GC733@empiric.icir.org> References: <20051107140451.GU91530@cell.sick.ru> <20051111140926.GC733@empiric.icir.org>
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On Fri, Nov 11, 2005 at 02:09:26PM +0000, Bruce M Simpson wrote: B> On Mon, Nov 07, 2005 at 05:04:51PM +0300, Gleb Smirnoff wrote: B> > I suggest to keep sending ARP requests while there is a demand for B> > this (we are trying to transmit packets to this particular IP), B> > ratelimiting these requests to one per second. This will help in a B> > quite common case, when some host on net is rebooting, and we are B> > waiting for him to come up, and notice this only after 1 - 20 seconds B> > since the time it is reachable. B> > Any objections? B> B> In response to the other replies to this thread citing broadcast B> pollution on Ethernet-based networks: B> Please add this functionality under a sysctl where it is turned off by default. B> B> It is desirable in situations where ARP entries cached further upstream are B> stale, but it may cause flooding in an environment where the layer 2 backbone B> hasn't been split or has not been segregated well. B> B> Other people cited examples where vendor switch implementations were B> retransmitting across VLANs -- this week I've been offering moral support B> to a friend who is dealing with similar VLAN brokenness at his $DAYJOB B> (there was an extension to 802.1d to support multiple spanning tree instances B> across VLANs which I think not everyone supports correctly). I'd like to see a proven evidence that this functionality leads to a measurable increase in broadcast traffic. Many modern operating systems behave in such way and no-one complains. The increase of broadcast traffic is very theoretical, it happens only when there are downed hosts. -- Totus tuus, Glebius. GLEBIUS-RIPN GLEB-RIPE
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