Date: Mon, 7 Dec 1998 09:52:38 -0500 (EST) From: Thomas David Rivers <rivers@dignus.com> To: rivers@dignus.com, ru@ucb.crimea.ua Cc: dillon@apollo.backplane.com, eischen@vigrid.com, hackers@FreeBSD.ORG, luigi@labinfo.iet.unipi.it, marcs@znep.com, nate@mt.sri.com Subject: Re: TCP bug Message-ID: <199812071452.JAA00490@lakes.dignus.com> In-Reply-To: <19981207163606.A7575@ucb.crimea.ua>
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> > On Mon, Dec 07, 1998 at 09:01:45AM -0500, Thomas David Rivers wrote: > > Ok - > > > > As I understood this discussion (which seemed clear to me); the > > problem was that an internal node (behind the firewall) couldn't > > get to some web sites because of fragmentation issues. The low > > MTU at the firewall/gateway broke path MTU discovery.. > > No, the problem is not with low MTU, but because AOL is blocking ICMP: > > PING aol.com (152.163.210.29): 56 data bytes > 36 bytes from www2-r10-P5-0-0.tpopr-rri.aol.com (152.163.133.6): Communication prohibited by filter > Vr HL TOS Len ID Flg off TTL Pro cks Src Dst > 4 5 00 5400 68cb 0 0000 ea 01 894d 194.93.177.113 152.163.210.29 > > ^C > --- aol.com ping statistics --- > 22 packets transmitted, 0 packets received, 100% packet loss Which messes up the Path MTU discovery... or so I thought... > > > > > So - a possible work-around to the problem should be to set the > > SL/IP MTU at 1500 at the gateway - right? > > Does your router run FreeBSD? If yes, how did you change MTU on SLIP? Yes, it's a 3.0-RELEASE box. To change the MTU I simply specified mtu 1500 on the ifconfig line for SL/IP. - Dave Rivers - To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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