Date: Sun, 29 Jul 2001 22:05:05 -0500 (CDT) From: kesu <kesu@kesuki.dyndns.org> To: Ted Mittelstaedt <tedm@toybox.placo.com> Cc: <freebsd-questions@FreeBSD.ORG> Subject: RE: Need help limiting bandwith ARP uses over cable modem. Message-ID: <20010729214847.X14350-100000@kesuki.dyndns.org> In-Reply-To: <000b01c117f0$9d971a40$1401a8c0@tedm.placo.com>
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My incoming bandwith is 560 killobits/second my outgoing bandwith is 128 killobits/second now surely you can see how receieving a saturating queue of packets on the inbound is going to generate _more_ outbound packets than my bandwith limitation. I am on average loosing 5% of all packets. I have anylized the tcp stream intensively and the vast majority of arp requests are duplicates in the first place, likely built up in my isps queue dutrring the minuter it takes for a reconnect. There is a genuine need to restrict the ARP packets when my isp refuses to. I am not concerned about the bandwith loss coming inbound it is really the outbound traffic that is causing packet loss. Restricting ARP has an emense benfit for cable modems, especially since they castrate the upstream levels, and there Is no isp choice. Especially since the low grade copper to my house prohibits DSL. I wouldn't have sent this e-mail if repeated letters of complaint to my isp hadn't failed to alleviate the problem for more than a week at a time. i need a _real_ solution, and controlling the bandwith ARP can use is the perfect solution. --- 12:00PM up 22 days, 11:49, 11 users, load averages: 0.00, 0.02, 0.00 Fortune of the day: Law of Selective Gravity: An object will fall so as to do the most damage. Jenning's Corollary: The chance of the bread falling with the buttered side down is directly proportional to the cost of the carpet. On Sat, 28 Jul 2001, Ted Mittelstaedt wrote: > How is any filtering that you do on your FreeBSD system going to affect the > incoming ARP packets? They are STILL going to come in - even if you block > them, your blocking them after your modem has received them and so > accomplishing nothing. > > Even a crummy Pentium 200 can saturate a 10Mbt Ethernet pipe without noticing > it and I doubt that your getting even close that throughput delivered to you > via cable. Your BSD Ethernet interface is literally loafing along when it is > recieving those 7,000 arp requests - it's not dropping the tcp packets as a > result of those. If anything is, it's your cable modem. Those recieved arps > are still going to be there whether you block them from your BSD box or not > and if your cable modem is being affected by them it will continue to be > affected by them, whether you block them or not. > > If you want to limit INBOUND arp bandwidth then complain to your ISP. Of > course - you can limit outbound ARP bandwidth all you want - but unless your > system is screwed it's not transmitting 64k of outbound arps. Further, I > doubt that the "consistent experience" your looking for is for OUTBOUND > bandwidth, I'm sure that what you care about is INBOUND bandwidth - and you > have no control over how much of a percentage of that is used by arps. > > Ted Mittelstaedt tedm@toybox.placo.com > Author of: The FreeBSD Corporate Networker's Guide > Book website: http://www.freebsd-corp-net-guide.com > > > >-----Original Message----- > >From: owner-freebsd-questions@FreeBSD.ORG > >[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of kesu > >Sent: Saturday, July 28, 2001 3:24 PM > >To: freebsd-questions@FreeBSD.ORG > >Subject: Need help limiting bandwith ARP uses over cable modem. > > > > > >Well I have a very low bandwith cap on my cable modem, and as soon > >as the modem reconnects i am flooded with about 7,000 ARP requests. > >(in the first 3 minutes) this can literally cause any number of tcp > >packets to get dropped. since arp tends to be more forgiving than > >tcp (especially for realtime situations) I would like to cap the > >ARP protocols bandwith usage to 64 Killobits per second in both > >directions over the cable modems interface. > >I have ipfw configured and in the kernel, and anyone who could tell me how > >to limit the bandwith of ARP would really help me get a more consistant > >experience from my cable modem. > > > >--- 12:00PM up 21 days, 11:49, 11 users, load averages: 0.00, 0.00, 0.00 > >Fortune of the day: > >"I'm all for computer dating, but I wouldn't want one to marry my > >sister." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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