On Thu, Nov 26, 2009 at 12:03:24AM +0100, Guillaume CHARDIN wrote: > > wget <ip address of the site in question> > > > > you can see the size being set in tcpdump. > > > > if it still stalls after setting to 1400, try something smaller 900 - > > just to make sure we are on the right track. > > > > Alex > > > > > I've done 4 tests > a) tcpdump in non promiscous mode and try to contact via wget > www.microsoft.com with a mtu set to 1400 : segment size is regulated > to 1360 so under the value > b) tcpdump in promiscous mode try to contact via wget > www.microsoft.com from win station same max mtu size : segment size is > regulated to 1360 so under the value > c) same as (a) but with a mtu of 1000 : packet size is maximized to 960... > d same as (b) but with mtu of 1000 : packet size is maximized to 960... > > > a) > # tcpdump -pni ppp0 host www.microsoft.com > tcpdump: verbose output suppressed, use -v or -vv for full protocol decode > listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 96 bytes > 22:16:31.535269 IP 86.69.85.63.49104 > 207.46.19.190.80: S > 1429337682:1429337682(0) win 5440 <mss 1360,sackOK,timestamp 24647950 > 0,nop,wscale 1> > 22:16:34.535269 IP 86.69.85.63.49104 > 207.46.19.190.80: S > 1429337682:1429337682(0) win 5440 <mss 1360,sackOK,timestamp 24648700 > 0,nop,wscale 1> > > b) > tcpdump -ni ppp0 host www.microsoft.com > tcpdump: verbose output suppressed, use -v or -vv for full protocol decode > listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 96 bytes > 22:21:24.527269 IP 86.69.85.63.3183 > 207.46.192.254.80: S > 824552434:824552434(0) win 65535 <mss 1360,nop,nop,sackOK> > > c) > tcpdump -pni ppp0 host www.microsoft.com > tcpdump: verbose output suppressed, use -v or -vv for full protocol decode > listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 96 bytes > 22:58:39.003269 IP 86.77.213.79.55709 > 207.46.19.190.80: S > 2417518931:2417518931(0) win 3840 <mss 960,sackOK,timestamp 25279817 > 0,nop,wscale 1> > > d) > tcpdump -ni ppp0 host www.microsoft.com > tcpdump: verbose output suppressed, use -v or -vv for full protocol decode > listening on ppp0, link-type LINUX_SLL (Linux cooked), capture size 96 bytes > 23:01:13.539269 IP 86.77.213.79.3433 > 65.55.21.250.80: S > 1538952923:1538952923(0) win 65535 <mss 960,nop,nop,sackOK> > > Ok so maybe its not mtu related ?! no ? what do you think about that Alex ? Well by the looks of things, I would guess you are loosing packets somewhere, I would presume than 960 mtu would work on all routers on the internet by now > -- It's not reality that's important, but how you perceive things.
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