How much buffer you have on the linux box ?. Maximum thruput at TCP level is
bounded by RTT*buffer_size. But doesn't explain physical errors , you should
have a bad cable.
"Simon Paradis" <(E-Mail Removed)> a écrit dans le
message de news:PSkIb.24391$(E-Mail Removed)...
> Hi,
>
> I'm having some TCP connectivity problems involving a WinXP box, Linux box
> and a router to share internet access and have a LAN for those two
machines.
> The problem is that TCP is dog slow and freezes when the box talks to
> themselves directly on the LAN side.
>
> Here is my setup:
>
> Windows XP box
> ------------------
> CPU: AMD AthlonXP 1.4 GHZ
> RAM: 256 MB
> NIC: Onboard Realtek RTL8139/810X Family Fast Ethernet NIC
> IP : 192.168.1.2
>
> Router
> ------------------
> Linksys BEFSR41 ver.3 with latest firmware 1.04.8 (with 4 ports 100
megabit
> switch)
> DHCP server disabled (I use fixed IP on WinXP & Linux)
> UPnP disabled
> NAT enabled (for sharing internet access)
> LAN side IP: 192.168.1.1
> WAN port connected to a Dlink DSL-302 DSL modem. There's no PPPoE, the
> connection works directly using DHCP like a standard LAN.
>
> Linux Mandrake 9.2
> ------------------
> CPU: AMD Duron 600 Mhz
> RAM: 448 MB
> NIC: AOpen AON-325 Fast Ethernet (based on RTL8139 chipset)
> IP : 192.168.1.3
> Kernel: 2.4.22-10mdk (stock kernel from Mandrake)
> NIC driver: 8139too
> ifconfig output:
> eth0 Link encap:Ethernet HWaddr 00:48:54:65:7F:5D
> inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:6271441 errors:3168383 dropped:0 overruns:0 frame:0
> *** I don't know when that huge amount of error occured ***
> TX packets:4413195 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:100
> RX bytes:290905469 (277.4 Mb) TX bytes:2019588565 (1926.0 Mb)
> Interrupt:9 Base address:0xef00
>
> TCP connection hangs shortly after starting. I made java utility for
> sending/receiving data over TCP (like ttcp). I tried it with the same
> hardware setup but running Solaris 9 x86 on the AMD Duron box and I was
> getting approximatly 95 MBit/s at the TCP level (just pure TCP I/O; no
disk
> read/write are involved). Taking into account TCP, IP, Ethernet headers
and
> preambles, this gives a raw line speed near 100 megabit/s ! I get the
> similar performance when running WinXP on the AMD Duron box. You
definitely
> cannot get over that speed. I was running Solaris CDE remotely through
using
> XDMCP and it was almost the same as working locally. Now with Linux; it
just
> sucks; an xterm can take 30 sec to appear. Once it's loaded; it work fine
> tough....
>
> Now with Linux, TCP connection hangs. I ran tcpdump on the Linux box when
> running the java program described above. It was sending data from WinXP
to
> Linux (one way only). You can see the unusual delays. I get the same
> problems when sending data from Linux to WinXP.
>
> ... [start of tcpdump] ...
>
> 13:05:29.400937 192.168.1.2.1130 > 192.168.1.3.5005: S
> 3336550493:3336550493(0) win 64240 <mss 1460,nop,nop,sackOK> (DF)
> 13:05:29.400998 192.168.1.3.5005 > 192.168.1.2.1130: S
> 2165233103:2165233103(0) ack 3336550494 win 5840 <mss 1460,nop,nop,sackOK>
> (DF)
> 13:05:29.401112 192.168.1.2.1130 > 192.168.1.3.5005: . ack 1 win 64240
(DF)
> ... [this is the first segment; normally several thousands of them should
> pass very quickly]....
> 13:05:29.440189 192.168.1.2.1130 > 192.168.1.3.5005: . 1:1461(1460) ack 1
> win 64240 (DF)
>
> ... [snip; only 21901 bytes sent after 3 seconds] ...
>
> 13:05:32.766509 192.168.1.3.5005 > 192.168.1.2.1130: . ack 21901 win 35040
> <nop,nop,sack sack 1 {20441:21901} > (DF)
> *** Very abnormal: 3 sec elapsed with no data from 192.168.1.2 ***
> 13:05:35.771118 192.168.1.2.1130 > 192.168.1.3.5005: . 23361:24821(1460)
ack
> 1 win 64240 (DF)
> 13:05:35.771192 192.168.1.3.5005 > 192.168.1.2.1130: . ack 24821 win 40880
> (DF)
> *** Again, 6 second delay ***
> 13:05:41.778868 192.168.1.2.1130 > 192.168.1.3.5005: . 23361:24821(1460)
ack
> 1 win 64240 (DF)
>
> .... [snip] ...
>
> 13:06:22.820826 arp who-has 192.168.1.2 tell 192.168.1.3
> 13:06:22.820964 arp reply 192.168.1.2 is-at 0:a:e6:21:71:e0
> 13:07:05.795333 192.168.1.2.1130 > 192.168.1.3.5005: . 27741:29201(1460)
ack
> 1 win 64240 (DF)
> 13:07:05.795593 192.168.1.3.5005 > 192.168.1.2.1130: . ack 29201 win 49640
> <nop,nop,sack sack 1 {27741:29201} > (DF)
> 13:07:05.795971 192.168.1.2.1130 > 192.168.1.3.5005: . 29201:30661(1460)
ack
> 1 win 64240 (DF)
> 13:07:05.796042 192.168.1.3.5005 > 192.168.1.2.1130: . ack 30661 win 52560
> (DF)
> 13:07:10.790827 arp who-has 192.168.1.2 tell 192.168.1.3
> 13:07:10.790958 arp reply 192.168.1.2 is-at 0:a:e6:21:71:e0
> .... [then nothing; TCP connection is frozen] ...
>
> As expected, the LED didn't blink too much on the router and the NIC's. I
> also tried uploading a big file from WinXP to Linux using sftp and got the
> same result. The upload hangs as soon as it starts. However, interactive
ssh
> sessions works fine. Downloading small (< 5kb) files using sftp also works
> ok.
>
> Now here is an interesting thing; when I link those two boxes using a
normal
> 100 megabit/s layer-2 switch, the transmission works fine but I only get
70
> megabit/s instead of 92/95 megabit/s using Solaris or WinXP.
>
> Even stranger; when running the same test on Solaris OR WinXP on the AMD
> Duron box through the Linksys router, the performance was still 95
megabits
> (the router was just as fast as my other little switch). When I download
> stuff on the net using the Linux or WinXP box, I can get ~215 kb/sec which
> is the max my DSL connection supports. Internet works just fine.
>
> If I do a netstat, it shows that very few TCP segments have been sent
during
> a time interval where several thousands of them should have passed.
However,
> If I do a ping flood with 65000 bytes packet (ping -A -s 65000
192.168.1.2),
> no packets are losts and the thing just run super fast with a steady round
> trip time of 11.5 ms (with ~1 ms mdev).
>
> I power-cycled the router and resetted it configuration several times and
> also tried it without hooking the DSL modem to it. I always get the same
> problem. Do you think it's due to the router or Linux ? I don't think it's
a
> cable problem.
>
> It looks like the problem is TCP related as the ICMP ping works juste
fine.
> Do you want can I do fix this ?
>
> Thanks for your help,
>
> My email is "simon [dot] paradis [at] usherbrooke [dot] ca".
>
>
>
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