LARTC - Feb 2006 - about the traffic control

Hi, all:
   I''m involved in the study about the QoS,but have some problems ,
hope
someone could help me answer:
    1. Why most traffic shaping implement in the egress side (Uplink) rather
        than the ingress side(Dnlink)?(e.g. why put the police rule on the
smaller
        bandwidth side but not put on the larger side)
  
    2. I can''t differ the functionalities exactly between SFQ and HTB 
        , they''re both the queueing disciplines,HTB is used to manage
bandwidth
        ,with the DRR displine in it , also be a scheduler to send packets,
       so, why we still need SFQ?
  
    3. Does anybody know that where I can find the VoIP and VOD traffic
     generator ? ''cause I want to evaluate the performance in the linux
DiffServ
     I don''t know if the iperf can generate the above mentioned
application traffic?
     
Fionna
   

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Hi Fionna :)

 * ???p?F <ttw_chien@yahoo.com.tw> dixit:
>     1. Why most traffic shaping implement in the egress side (Uplink)
rather
>         than the ingress side(Dnlink)?(e.g. why put the police rule on the
smaller
>         bandwidth side but not put on the larger side)
    You cannot shape ingress traffic, because you cannot control the
sending speed of the remote equipment. The only thing you can do is
to drop packets, but that doesn''t make bandwitdh smaller, it just
cause less packets to arrive to applications, so while you
effectively set a smaller bandwidth for applications, the cable BW is
fully used.

    I suppose that ECN can be used to shape incoming traffic, but I
don''t know.
   
    Raúl Núñez de Arenas Coronado

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