two questions:1 relationship between dummynet and wireshark 2 how to add latency for each packet to be sent

nangergong nangergong at gmail.com
Thu Nov 25 15:31:18 UTC 2010


Hi, all:

1  relationship between dummynet and wireshark

I have a question on the relationship between dummynet and wireshark. Does
wireshark capture packets before dummynet starts working or after? Which of
the following charts is right?

(1)
      send packets
capture                                   add pkt loss, delay..
A------------------> wireshark -------------------->
dummynet--------------------------->

                                                                add pkt
loss,delay...                      capture
network----------------->dummynet ------------------------->
wireshark-------------> B

or

(2)
      send packets                              add delay,loss
                           capture
A------------------> dummynet -------------------->
wireshakr--------------------------->

                                                                add pkt
loss,delay...                      capture
network----------------->dummynet ------------------------->
wireshark-------------> B

At first, I think (1) is right, and I did a test using "ping". However
during my following test, it seems that (2) is the fact:

I have two machines, A and B. When I play music on A, the RTP packets flow
from A to B.  I added a pipe with packet loss and bandwidth limitation,
which regulates the flow from A to B. Then I captured packets on A using
wireshark. If the chart (1) is right, then the packets I captured on A
should be the same to the music I played on A, however, this is not the
truth.

2 how to add latency for each packet to be sent

  I want to vary the delays(latencies) for different packets. So, is there a
way to add latency for for each packet to be sent. For example, bind one
pipe to one packet. Thank you!


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