Date: Thu, 30 Aug 2001 21:43:51 -0700 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Hans Christensen" <hansc@loki.datamatrix.com>, <freebsd-questions@FreeBSD.ORG> Subject: RE: SLOW ftp transfers one way Message-ID: <002701c131d7$8808eae0$1401a8c0@tedm.placo.com> In-Reply-To: <200108310044.f7V0ies17607@loki.datamatrix.com>
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>-----Original Message----- >From: owner-freebsd-questions@FreeBSD.ORG >[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Hans >Christensen >network. This linux box had the same type of performance problems. Slow puts >to Site A and reasonable gets from Site A. > I have seen this before as well, between boxes at the colocation >facility and again across different class c subnets. Sprint claims that the >problem lies with the MTU settings of the boxes at the "linux side" and the >"colo side." This smells wrong to me, but I confess that I don't really know >that it is wrong. It IS wrong. Your interface into the server is Ethernet, any MTU setting you do is going to be the standard Ethernet MTU of 1500 and you should NOT mess with this. Once the packets are received by Sprint's routers if any MTU changes need to be done then Sprint's routers will fragment them appropriately. However, like most BALONEY there is a grain of truth in it. You just need to understand that most Telco people don't know anything about networking in order to extract it. See the next comment for an explanation. >I have looked in the FBSD bug reports for any indication >of a similar problem and do not see any so far, but I have seen several >questions on the mailing list archives. Most of these are dismissed as >improper configuration of ethernet cards. I find it very hard to believe that your Intel card is misconfigured. I have tried these suggestions but >found no relief. > I ftp close to a GB of info every night into Site A and I need it to go >faster than it has been going, but I'm stumped. Anybody got any clues for >the clueless? > What kind of firewalling are you running? Many administrators MISTAKENLY believe that ALL ICMP packets are supposed to be filtered out. This blocks important protocols like MTU Path Discovery which if blocked will kill performance across a WAN where different links in the WAN use different MTU sizes. TURN OFF ANY ICMP FILTERING and see if the problem goes away. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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