[e2e] Question on TCP throughput and host's access speed

[Jing Shen]

Hi,

I met a question with upload speed and network access
speed. 

We use two leased line from ISP. One is a 2Mbps ADSL
the other is a 100Mbps fiber link. Usually it is
required to upload files to a server in Japan. 
To my understanding, upload speed should be higher if
leased line is used. On the contrary,  upload using
ADSL is a little faster than using Fiber link, while
packet loss and retransmission happen more frequently
when I use Fiber link. Analizing routing path between
our computer and server in jappan, we found there is
no difference between ADSL access and Fiber Link
beside the access method.

If I do not make a mistake, TCP throughtput is
determined by bottleneck bandwidth, RTT and its
fluctuation. So, although ADSL's  speed is much slower
than fibre, the upload speed should be similar when
bottleneck is the same, or ADSL should be slower. 

Why the phenomon comes up? 


regards

Jing Shen 

  

_________________________________________________________
Do You Yahoo!?
150ÍòÇúMP3·è¿ñËÑ£¬´øÄú´³ÈëÒôÀÖµîÌÃ
http://cn.rd.yahoo.com/mail_cn/tag/yisou/music/*http://music.yisou.com/
ÃÀÅ®Ã÷ÐÇÓ¦Óо¡ÓУ¬ËѱéÃÀͼ¡¢ÑÞͼºÍ¿áͼ
http://cn.rd.yahoo.com/mail_cn/tag/yisou/image/*http://image.yisou.com
1G¾ÍÊÇ1000Õ×£¬ÑÅ»¢µçÓÊ×ÔÖúÀ©ÈÝ£¡
http://cn.rd.yahoo.com/mail_cn/tag/1g/*http://cn.mail.yahoo.com/event/mail_1g/