downloading speed

We are level one ISP. one of my customer is connected to fast ethernet.
His link speed 100,000 kbps. while downloading any thing from net he
downloading speed donot go above 200 kbps.
While doing multiple download he get aroung 200 kbps in every window. But
when he close all the windows no change in downloading speed is observed.



Have him do a traceroute from his PC or router to where he is trying to
download from. Where is it choking?

Several windows in the same PC, doing file transfer in parallel, each get the same speed as one.
The speed is peaking at some specific speed every single time, and the several windows reach this peak.

I smell classic TCP window size bumping into (bandwidth x delay).

Have you tried with iperf, using UDP ?

Mike Lyon wrote:

Based on the screen shot he's getting, 1536 bps or 192KB. Also if he is
opening several windows but downloading from the same source it may be a
congestion control mechanism on the server or hosting provider side. What's
the utilization on the RT, DSLAM and BRAS, all factors to performance.


chandrashakher pawar wrote:

No errors on the interface.
none of our customer on this router has complait us this issue
i have changed this to "negotiation auto" as suggested by one of our member.
tommorow customer will test again and reply.
round-trip-time is good, no bacbone chocked.
Unit will not make bit differnce as: The customer tried troubleshooting the
issue after connecting laptop directily to the 100 mbps link.
In that case also the result was same.

Note that your screenshot displays bytes, not bits. So it will display one-eighth the download speed measured in bits.

Check the TCP tuning on the downloading PC. The fact that multiple windows achieve a higher aggregate speed points to this. Use the Google link I supplied earlier, also search "Bandwidth-delay product". Are both ends of the link a substantial geographic distance (several miles) apart?

Note that the adjustments for TCP tuning are to the TCP stack on the machine doing the download, not the network gear.