[ns] What is Packet Interval !!

[Teerawat Issariyakul]

Hi,

If you are talking about the time that you need to transmit packet, it is
actually defined by two things 1) packet size and 2) link
characteristics.

There is a detailed explanation of the packets and the scheduling (and
timers) in the book from Springer:

T. Issaraiyakul and E. Hossain, "Introduction to Network Simulator
NS2", Springer 2008.

Here is the link:
http://www.springer.com/engineering/signals/book/978-0-387-71759-3

You might also find the following slide useful:
http://www.ece.ubc.ca/~teerawat/NS2.htm<http://www.ece.ubc.ca/%7Eteerawat/NS2.htm>


The following might be useful to you:

You can see the default packet size in the file ns-default.tcl (chapter
3). The packet size is different from one protocol to another. For
example, for TCP,

Agent/TCP set packetSize_ 1000

The second part depends on what link layer you are using. In a wired
network, the link layer delay is defined in a variable link_ of class
SimpleLink (chapter 7). This variable is bound to C++ class  LinkDelay.
It schedule two events: 1) the packets leave one place, and 2) the
packet arrive at another place. Class LinkDelay has variables bandwidth_
and delay_ (propagation delay). Based on these two variable as well as
the packet size, you can compute the packet interval.

Hope this would be helpful.

Best,
Teerawat

On 10/27/2008, "Mathiew Moussa" <mmm59 at aub.edu.lb> wrote:

>
>Hi Jianliang,
>
>Thanks for the prompt reply, i appreciate it.
>
>I was wondering .. ok i'm in the ns-default.tcl file ... but there's  
>nothing called 'packet interval'. Does have a different name or  
>terminology, where is it located in the file ?
>And what does it exactly 'packet interval' , is it like TTL ?
>
>and about adding it to the MY tcl as an alternative to the above, can  
>you give me an example or how to add it.
>
>Excuse me but I'm new at NS2 and details are important :)
>
>Thanks Alot.
>Mathiew
>
>
>
>
>
>Quoting J GAO/Jianliang GAO <j.gao at Bradford.ac.uk>:
>
>> Hi Mathiew,
>>  You can change Packet Interval value in the file ns-default.tcl in   
>> folder ns-2.xx\tcl\lib. However, it is not so convenient to change   
>> the value of interval by modifying ns-default.tcl every time you   
>> test your code in different interval time. There is an alternative   
>> way to change the value of interval. You can change the value in   
>> your own .tcl code in the corresponding part of code of traffic you   
>> use. Obviously, this way facilitates your test.
>>   To find out what exact reason causes the error, using ddd or gdb   
>> to debug and track the code is very helpful.
>>   Regards,
>>
>>
>>
>> J GAO/Jianliang GAO
>> 2008-10-27
>>
>>
>>
>> 发件人： Mathiew Moussa
>> 发送时间： 2008-10-27 16:34:13
>> 收件人： ns-users at ISI.EDU
>> 抄送：
>> 主题： [ns] What is Packet Interval !!
>>
>>
>> Hi All ns-users,
>>
>> Does anyone know what "Packet Interval" in NS2 is and WHERE can when
>> change it.
>>
>> you see im using the SMAC and it was giving me an error "Couldn't
>> Schedule Timer" after i ran my TCL script .. I got an answer from one
>> of the guys that it might possibly have to do with the packet interval.
>>
>> Thanks in Advance.
>>
>> Mathiew
>>
>
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