Messages in this thread |  | | Date | Mon, 14 May 2001 18:19:26 +0200 | From | tdanis@canal-pl ... | Subject | Re: Linux TCP impotency |
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On Sun, May 13, 2001 at 10:54:15PM +0200, ahu@ds9a.nl wrote: > On Sun, May 13, 2001 at 09:38:53PM +0200, clock@ghost.btnet.cz wrote: > > Using 2.2.19 I discovered that running two simultaneous scp's (uses up whole > > capacity in TCP traffic) on a 115200bps full duplex serial port nullmodem cable > > causes the earlier started one to survive and the later to starve. Running bcp > > instead of the second (which uses UDP) at 11000 bytes per second caused the > > utilization in both directions to go up nearly to 100%. > > > > Is this a normal TCP stack behaviour? > > Might very well be. Read about different forms of (class based) queuing > which try (and succeed) to improve IP in this respect. TCP is not fair and > IP has no intrinsic features to help you. http://ds9a.nl/2.4Routing contains > some explanations and links. > > SFQ sounds like it might fit your bill. > > Regards, > > bert > > -- > http://www.PowerDNS.com Versatile DNS Services > Trilab The Technology People > 'SYN! .. SYN|ACK! .. ACK!' - the mating call of the internet > -
I was about to report the same 'od' behaviour : I have 3 machines, connected via a HUB at 100 Mb/s half duplex.
From machine A : rsh B dd if=/dev/zero bs=8192 | dd of=/dev/null
=> transfert around 10/11 MB/s (B => A)
Now, I start a second transfert from machine C :
rsh B dd if=/dev/zero bs=8192 | dd of=/dev/null
=> transfert around 10/11 MB/s between B and C, almost nothing between A and B (ie, the connexion is stalled between A and B).
If I stop the second transfert, I takes many seconds for the transfert to restart between A and B.
On a highly saturated network, I have already seen such a behavior.
Is that related to the IP adresses, the lowest being served first ?
A+, -- Thierry Danis - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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