Hi, I suggest you check the duplex mode on your ethernet interface and your switch. I had a problem similar to yours just a couple of months ago, and tracked it down to the interface auto-negotiating into half instead of full duplex. On a busy ethernet interface that can cause enough collisions to affect TCP throughput substantially, due to that small amount of packet loss. Unfortunately under Linux there is no "good way" to find out the link speed and duplex condition portably among different ethernet adapters, at least that I am aware of. Here is what I do: $ dmesg |egrep eth[0-2] eth1: Intel Corp. 82557 [Ethernet Pro 100], 00:A0:C9:39:4C:2C, IRQ 19. eth2: ns83820 v0.15: DP83820 v1.2: 00:40:f4:17:74:8a io=0xfebf9000 irq=16 f=h,sg eth2: link now 1000 mbps, full duplex and up. Also unfortunately, most ethernet drivers don't bother reporting this, although you can hack it into your drivers if it is important to you. But another good way to check is to examine your switch: switch0#sh int fa0/2 ... Auto-duplex (Full), Auto Speed (100), 100BaseTX/FX ... This shows 100/full auto-negotiated. Really, this is a bad thing to do, as we should be setting all our ports to 100/full in the configuration, but it probably won't be done until it bites us in the ass. :-) switch0#sh int fa0/24 ... Full-duplex, 100Mb/s, 100BaseTX/FX ... This is a port which has been fixed to 100/full, because it *did* bite us in the ass. It's an uplink to a router and does several mbits/sec 24x7, and that packet loss affected all the TCP sessions going over it, limiting them to around 400Kbits/sec throughput due to TCP backoff :-( I hope this is helpful. -- Jeff S Wheeler jsw@five-elements.com Software Development Five Elements, Inc http://www.five-elements.com/~jsw/ On Wed, 2002-07-03 at 22:20, Rajeev Sharma wrote: > hi all.... > > I am stuck with a problem of my network.. > > my one debian box is very unstable ..some time it transfer data > smoothly(997.0 kB/s)and sometime it hanged up at 123.0 kB/s.. > and when i use > > ping -f 192.168.x.x > > it shows 1% data loss and some time 0% data loss.. > > > i have checked my cables,switch ...but no use .... > > pliz help me.... > **snip**
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