Re: Fw: How can I calculate the packet loss of one flow(session) on the run timeRe: Re: [ns] packet loss!

[Brian Lee Bowers <bowersb@lanl.gov>]

On Thursday 21 June 2001 12:57, liu yong wrote:
> Hi,
>   How can I calculate the packet loss of one flow(session) on the
> running time.I know I can get this information by proprocesstion
> the trace file.My problem is how to know it in the running
> time.Thank for your help.

Several methods come to mind for determining number of packets lost 
for a flow:

1)  parse the trace file.  This is fairly simple with Perl.  
Depending on how much of the information you need, the regular 
expressions can get a little nasty looking, but they aren't difficult.

2)  modify the sender to output the information you need.  This isn't 
quite precise, because you have to assume that any packet 
retransmitted was lost.  With two way traffic, a retransmission might 
mean that the packet was lost, the ACK was lost, or simply that the 
sender timed out the packet.

3)  modify the sender to include a "persistent" variable.  The 
variable is used to count the number of retransmissions made by the 
sender.  You can then use a "record" function (see Greis's tutorial 
for an example) to get the number of retransmissions per your own 
time granularity.  After you get the number of packets dropped, you 
can reset the variable.

-- 
Brian Lee Bowers	|	RADIANT Team
bowersb@lanl.gov	|	Los Alamos National Laboratory