RE: [ns] issues on ErrorModel AGAIN!

["Hong Bin Liao" <hbl@msrchina.research.microsoft.com>]

In the NS-2 implementation, error model is insert before the queue
module or the link module. For the insertion before the link module, if
a corrupted packet is immediately dropped and the resume handler of this
packet are invoked after a random period between 0 to (PacketSize/BW).
This means a corrupted packet consumes less bandwidth than a correct
packet. There is also another fatal issue for time continuous error
model, since a corrupted packet takes less flight time than a correct
packet, it cause more burst error than error model with bit, byte, etc
as the error unit.

-hongbin

> -----Original Message-----
> From: jahn-isi [mailto:jahn@ISI.EDU]
> Sent: Saturday, July 07, 2001 5:21 AM
> To: Hong Bin Liao
> Cc: ns-users@ISI.EDU
> Subject: RE: [ns] issues on ErrorModel AGAIN!
> 
> 
> I am not sure why there is a delay before notifying the packet
> corruption to the module called the error model. 
> 
> But, corrupted packets are immediately sent to the specified target
>  (which is a neigbor node's link layer or the next low layer 
> in wireless networks)
>  without any delay after scheduing the notification event 
> with some arbitrary
> delay.
> 
> You can see this flow by using a gdb debugger.
> -jahn
> 
> 
> 
> -----Original Message-----
> From: owner-ns-users@ISI.EDU 
> [mailto:owner-ns-users@ISI.EDU]On Behalf Of Hong Bin Liao
> Sent: Friday, July 06, 2001 6:01 PM
> To: NS-2, USERS (E-mail)
> Subject: [ns] issues on ErrorModel AGAIN!
> 
> 
> Hi, Folks
> 	I sent the following letter several days before. I got no answer
> for it. IMHO, it's very fatal issue on the correctness of model of the
> systems. Could anyone give me answer of it?
> 
> Hi, folks
> 	after reading the source code of errmodel.cc, I wonder why the
> resume handler should be delayed for a random period between 0 to
> (PacketSize/BW). why not this packet with error is delayed 
> for a period
> (PacketSize/BW)?
> 	The former cause more burst error when error unit is bit, byte
> or time (in two/multi state error model).
> 
> 
> HongBin L.
> 07/06/2001
> 
>