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Re: why upload with adsl is faster than 100M ethernet ?

  • From: Joe Shen
  • Date: Fri Oct 15 04:16:35 2004

Hi,

the network path is:


         |-(ADSL)--------\
customer/                 --Edge_router---...---Japan
Server  
        \-(100Methernet)-/


So, from edge_router to Japan server the path is
identical. 

> 
> There is something wrong with both scenarios.
> 
> A 5 Mbyte file is 40 megabits.  With overhead, it
> should
> transfer in about one-half second over a 100 Mbps
> ethernet
> connection and somewhat less than 30 seconds on a
> 2Mbps
> connection.

Yes. But, for ftp  TCP control real end-to-end
transmission speed. 

I attached a monitor computer to our core router along
the path between customer's site and server.
Monitoring computer ping customer's site by targeting
both ends of ADSL line and ethernet line. The
measuring is scheduled 20packet per 20seconds, we also
ping each hop address along the path to server. The
result shows there is no packet loss along from
monitoring computer to customer site, but packet loss
increase at a special hop along the path to server in
japan. 

So, we think the bottleneck is not inside our network.
And, TCP connection between customer's computer and
its server should be affacted by same bottleneck. So,
the uploading speed should be similar (?), but it
shows so much difference!

> 
> Look for duplex mismatch or something similar.

I disable autonegotiation of ethernet. So, there is no
such situation.

> 
> Oh!  There's another WAN link in the picture!  What
> are the MTU
> settings?  Are the packets being fragmented?  Iis a
> firewall
> blocking all ICMP somewhere including path MTU
> discovery?

the measurement is taken without firewall in customer
site. And, no packet filtering is enabled inside our
network. 

> 
> Note that this isn't exactly within the realm of the
> NA(North American)
> Network Operators Group, but the photons don't
> respect political
> boundaries so you may get appropriate answers here.

Thanks for all your helps. To me, knowledge should be
shared around world no matter where people live.
Luckly, NANOG/RIPE and some other group open to the
wolrd. 

regards

Joe 



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