speed loss

Arkadiusz Miskiewicz misiek at pld.ORG.PL
Thu Sep 5 04:20:04 EST 2002


I'm using 2.4.18 + orinoco_cs driver v0.11b in such setup:

Internet                         3km
(DSL link)--eth0[router 1]weth1 ~~~~~~ weth1[router 2]
                                       ~ 2m
                                       laptop with win XP

wethX means orinoco wireless card (running under Linux).
Each cards works in ad-hoc mode. Routing between router1
and router2 is done directly via wethX while laptop connects
via weth1 and is using PPP over Ethernet. Encryption is turned off.
Static arp is set up on both routers. Router 1 has direct(?)
antenna and router 2 has sector antenna. Laptop doesn't have any
antena beside internal atnenna inside of avaya cards. iwspy
on router2 shows link quality as about 15-20 for router1 and
about 30-35 for laptop.

When downloading something from router 1 to router 2 (or back)
I have ~600kb/s but when laptop connects to weth1 through
PPPoE and starts downloading something from router 1 then speed
goes down: from 600kb/s down to 200kb/s and on laptop download
speed is only something about 60kb/s.

200kb+2*60kb/s=320kb/s (on weth1) which is much less than 600kb/s
that I was having without laptop downloading something.

Also when laptop starts downloading from router 2 (only 2m away)
and then I start downloading something from router 1 to router 2
I will get only about 20kb/s while laptop downloads with > 500kb/s.
Band depends on signal strength?

I hope that this doesn't mean that when more clients gets connected
to router2 then maximal traffic will go down much lower 320kb ;-(

Is this normal behaviour with these cards? If yes then maybe there
is something that I can do to get things better (set some rts,
frag settings?). Add second wlan card and use it only for connection
with router1?

Arkadiusz Miśkiewicz   IPv6 ready PLD Linux at http://www.pld.org.pl
misiek(at)pld.org.pl   AM2-6BONE, 1024/3DB19BBD, arekm(at)ircnet, PWr

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