[LARTC] can't guaranteed to TCP traffic with HTB

["openings" <openings@palgong.knu.ac.kr>]

Hi.

What I want
====I want to guarantee bandwidth of TCP traffic when there is background UDP traffic.


Testbed setting
=====webserver---1----                                                 ---5----- Host 1
                           |                                                 |
                          +----3----- Linux TC ----4-----+
                           |                                                 |
UDP src-----2---               eth0        eth1              ---6-----Host 2


Link speed
====
1, 2, 4, 5, 6 : 10Mbps
3 : 100Mbps


Traffic Generation
======"UDP src" machine generate background UDP traffic at 10Mbps to Host 1.(generator : MGEN 4.0)
Host 1 and Host 2 Download files from "webserver" by HTTP. (TCP traffic)


Seudo tc command
======add qdisc dev eth1 root handle 1: htb default 2
add class dev eth1 parent 1: classid 1:1 rate 10Mbit ceil 10Mbit
add class dev eth1 parent 1:1 classid 1:2 rate 1Mbit ceil 9Mbit         <== UDP traffic
add class dev eth1 parent 1:1 classid 1:3 rate 3Mbit ceil 3Mbit         <== TCP traffic of Host 1
add class dev eth1 parent 1:1 classid 1:4 rate 1Mbit ceil 1Mbit         <== TCP traffic of Host 2


Problem
===
I want to guarantee Host1 TCP and Host 2 TCP traffic by rate value. (3Mbps, 1Mbps)
but when I start test, UDP traffic dominate 9Mbps speed. (it used full of ceil rate)
the ramainder bandwidth is divided by Host1 TCP and Host2 TCP. (very slow!)
Why TCP traffic can't get bandwidth of rate setting.?
UDP traffic's rate value is 1Mbos,  nevertheless UDP traffic get 8Mbps. 
Why rate value is not guaranteed ?
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