Date: Fri, 17 Dec 1999 14:30:10 -0800 (PST) From: daniel B <danielb@pacex.net> To: Juha Saarinen <juha@saarinen.org> Cc: freebsd-questions@FreeBSD.ORG Subject: RE: Not such good networking performance with FreeBSD Message-ID: <Pine.BSF.4.10.9912171417430.2761-200000@almazs.pacex.net> In-Reply-To: <LNBBIBDBFFCDPLBLLLHFMEGNGGAA.juha@saarinen.org>
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[-- Attachment #1 --] Thanks for the info; ATM is cell relay so if too many cells are dropped by your upstream/ISP it cause alot of retransmits, so unless you're running ATM you are forced to resend the whole IP packet again (ATM cells are very small byte-wise). I just did traceroute wiith -S option to cassandra.paradise.net.nz and realy bad latency with 30% loss (see attached file). I also have to deal with other non-FreeBSD issues i.e my dialup switch, teleco local loop, DSL loop e.t.c Dan On Sat, 18 Dec 1999, Juha Saarinen wrote: > Hi Daniel, > > I can only give you some general advice based on my experience with RADSL > (rate-adaptive DSL), and not anything terribly useful for FreeBSD... > > My telco runs ATM over DSL over which a PPP connection to my ISP is > encapsulated, so to speak. To start with, the telco had some problems with > its DSLAMs that caused long pauses and sometimes routing timeouts, making > interactive apps like ssh unusable. The telco said this was partly due to > ATM cells being lost which is disastrous for the larger IP packets, as it > causes lots of retransmissions... not so sure about that, but anyway, it > shows the complexity of squeezing that amount of bandwidth through plain old > copper wires, I guess. > > Even though the router says I've got 5.7Mbps (bits per second) to the > exchange, the telco appears to have capped each TCP session at 2Mbps max > (grrr...). That's still pretty good, but what complicates things for me is > the high latencies I see as soon as I connect to servers outside New > Zealand: > > traceroute to pacex.net (204.1.219.156), 30 hops max, 40 byte packets > 1 m10 (192.168.1.254) 1.075 ms 0.993 ms 0.913 ms > 2 203-79-82-254.adsl-wns.paradise.net.nz (203.79.82.254) 86.952 ms > 85.922 ms 66.505 ms > 3 192.168.253.225 (192.168.253.225) 45.744 ms 45.747 ms 45.314 ms > 4 kelly.ipnet.paradise.net.nz (203.96.153.138) 46.478 ms 45.642 ms > 46.252 ms > 5 cassandra.paradise.net.nz (203.96.152.3) 46.431 ms 45.809 ms 46.426 > ms > 6 a4-0-0-5.akbr1.netgate.net.nz (202.37.246.77) 55.911 ms 56.173 ms > 56.100 ms > 7 a0-0-0-2.tkbr1.netgate.net.nz (202.37.246.121) 57.310 ms 56.517 ms > 59.378 ms > > Leaving NZ, going to LA: > > 8 s1-1-4.labr1.netgate.net.nz (202.37.245.166) 238.127 ms 181.145 ms > 181.776 ms > 9 s5-0-0.lsanca1-cr1.bbnplanet.net (4.24.24.17) 180.932 ms 185.284 ms > 181.803 ms > 10 p2-1.lsanca1-ba1.bbnplanet.net (4.24.4.5) 184.113 ms 180.490 ms > 181.832 ms > 11 p7-0.lsanca1-br1.bbnplanet.net (4.24.4.2) 236.089 ms 237.078 ms > 236.339 ms > > <snip> > > 22 dsl1.irvnca01.us.ra.verio.net (192.215.247.103) 218.263 ms 218.406 ms > 215.212 ms > 23 compappcon-dw.customer.ni.net (204.1.216.14) 216.128 ms 217.187 ms > 218.471 ms > 24 almazs.pacex.net (204.1.219.156) 272.606 ms 273.758 ms 272.252 ms > > These are quite good roundtrip times for me actually. Sometimes they go well > into the 300-400ms range, which really makes applications that depend on > opening lots of connections and getting small files (like Web browsing) > suck, despite my multi-Mbps connection. > > Anyway, what I've found to help on all operating systems apart from FreeBSD > is to enable and tune the TCP High Performance extensions settings (RFC > 1323). It's less than obvious how you do this on FreeBSD, unfortunately. > This is what I've dug up so far... correct me if I'm wrong by all means. > > Put: > > tcp_extensions="YES" > > into /etc/rc.conf > > Then, it looks like you have to use the sysctl command to check and tune > some of the TCP settings: > > sysctl -w net.inet.tcp.sendspace=65536 && sysctl -w > net.inet.tcp.recvspace=65536 should give you 65KB TCP windows -- for some > reason, FreeBSD defaults to 16KB which is quite small. > > There are two more settings which I can't find documented anywhere, but > which I suspect affect things as well: > > net.inet.tcp.mssdflt: 512 (is this the default Maximum Segment Size? > shouldn't it be 1460 bytes?) > net.inet.raw.recvspace: 65536 (I've bumped it up as an experiment -- think > the default is 8192). > > sysctl -a | less shows you all the settings. > > Other than that, having an MTU/MRU of 1500 seems to work the best, and you > might want to check that you're not using e.g. PPP compression settings that > aren't compatible with with your ISP's peer. I have no idea how well stuff > like PPP address field and header compression works with high bitrate > connections, but I suspect that enabling them would add latency. > > Hope the above is of some use to you... > > > Cheers, > > -- Juha > > > > -----Original Message----- > > From: daniel B [mailto:danielb@pacex.net] > > Sent: Saturday, 18 December 1999 06:41 > > To: Juha Saarinen > > Cc: freebsd-questions@freebsd.org > > Subject: RE: Not such good networking performance with FreeBSD > > > > > > Sorry to intrude on this thread; but I am kinda having the same problem. > > My DSL speed was kinda OK when I wwas running 2.2.8 but ever since I > > upgraded to 3.x releases I just get poor performance and sometimes ssh > > kinda hungs up when accessing lan via ppp. > > Are there tricks and ways to get better networking performance on FreeBSD? > > this may soung very trival but I have realy noticed performance drop on > > this FreeBSD boxens. > > > > Dan > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message > [-- Attachment #2 --] 1 router (204.1.219.129) 0.765 ms 0.774 ms 0.876 ms (0% loss) 2 204.1.216.1 (204.1.216.1) 19.302 ms 16.422 ms 16.624 ms (0% loss) 3 fa-6-0-0.a02.irvnca01.us.ra.verio.net (192.215.247.93) 10.934 ms 11.669 ms 12.324 ms (0% loss) 4 fa-0-1-0.a03.irvnca01.us.ra.verio.net (192.215.247.96) 12.351 ms 12.668 ms 11.990 ms (0% loss) 5 vsc-irvine.pao6.verio.net (129.250.17.9) 28.288 ms 28.293 ms 28.025 ms (0% loss) 6 p3-1.paix-bi1.bbnplanet.net (4.0.6.6) 25.805 ms 26.045 ms 26.900 ms (0% loss) 7 4.0.6.101 (4.0.6.101) 27.035 ms 26.259 ms 26.890 ms (0% loss) 8 p6-0.lsanca1-br2.bbnplanet.net (4.24.5.197) 36.868 ms 37.462 ms 36.978 ms (0% loss) 9 p2-0.lsanca1-br1.bbnplanet.net (4.24.4.13) 38.286 ms 36.196 ms 36.017 ms (0% loss) 10 p7-0.lsanca1-ba1.bbnplanet.net (4.24.4.1) 39.182 ms 37.342 ms 38.295 ms (0% loss) 11 p0-0-0.lsanca1-cr1.bbnplanet.net (4.24.4.6) 40.228 ms 37.426 ms 40.355 ms (0% loss) 12 s0.telecomnz.bbnplanet.net (4.24.24.18) 39.326 ms 38.604 ms h1-0.telecomnz.bbnplanet.net (4.24.24.6) 39.252 ms (0% loss) 13 * * * (100% loss) 14 * * * (100% loss) 15 paradise.wwbr1.netgate.net.nz (202.37.247.230) 393.312 ms 462.471 ms * (33% loss)
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