ADSL cant do up and down??

Slime101

Slime101

Slime101

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We have a standard business ADSL service, the download speeds are good, and as expected the uploads are rubbish, the problem arises when we try and do both - if we are uploading and downloading symaltaniously the whole system grinds to a halt and the speeds drop to a crawl.

Is this normal?
 
If your uploading excessively fast saturating the upstream it can drown out acks and bring everything to its knees - doesn't normally happen tho.

Make sure RWin and MTU are set correctly on the PCs and routing hardware.
 
If your maxining your upload you cant acknowledge the packets you are downloading so you download slower
 
I dont really control the speed, i just set the FTP off and let it run....

How would i set the MTU and RWin and what should they be set to??
 
As implied, the effect that maxing out in one direction will slow down the other is a feature of TCP/IP - it's not unique to ADSL...

Unless you've already changed your MTU there's nothing to be gained by changing it. RWIN is configured by a registry setting in Windows.
You shouldn't need to touch either and they likely won't make any real difference. Either throttle the FTP upload or live with it.
 
Shame :(

Does the same happen on all types of connections or is ADSL more succeptable as ive never noticed it on my cable connection altho it doesnt get the hammering my work one does.
 
Like I said, it's common to any connection. You can do the same with a run of Cat5 between two machines, it's just harder to do (because it's faster).
 
Only TCP is affected by the behaviour because it requires a little upstream in order to send back the ACKnowledgement packets.

It has nothing to do with ADSL per se. ADSL is a full duplex connection. It allocates a dedicated frequency range for upstream, and a larger dedicated frequency range for the downstream.
 
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