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Re: CBQ question




On Mon, 4 Sep 2000, Idan Sofer wrote:

> I tried using fair queue to divide the bandwidth so me and the network
> have a relation of 1:1 at the worst case.
> However, the problem is that CBQ can control what the linux box SENDS but
> not what it recieves, that means, i can prevent the network to eat up all
> bandwidth, but not the linux box.

currently existing QoS software (that i'm aware of) control outgoing
packets - they cannot truly control incoming packets, because IP does not
support that (you need to ask the sending router to set the Qos parameters
for your connection, and that is not supported by currenly used _common_
protocols - its possible by RSVP over IP, as far as i know, but that's not
widely deployed).

however, if you'r willing to solve the problem for TCP only connections,
you could have some control on transmisison speed by playing with the
window side inside the kernel, or (as someone suggested here) by playing
with the application software.

this problem annoyed me when downloading files caused telnet/ssh 
connections to be un-useable. i modified the kernel to allow me to limit
the window size my linux box advertisez for all connections that are not
going into port '23' (telnet port) on the remote machine. with the
specific properties of my connection (i.e. bandwidth and connection
latency) it alloed me to use about 3/4 of the bandwidth for one FTP
connection, and have the telnet connection work in a more-or-less
responsive manner at that time. if you're interested in trying out this
method, i'd be happy to share the information with you. this will be
useful for ISDN and frame-relay connections - according to my math, for
modem connections, this solution isn't good enough to allow interactive
telnet or shh connections.


guy

"For world domination - press 1,
 or dial 0, and please hold, for the creator." -- nob o. dy


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