Reviewer 1.: There appears to be too much reliance on ref. [12] which may be available to the general audience. It is better to summarize main results in this paper as much as possible.

Authors' comment:
 Summarized the main results in abstract. 
 

Review 2.: 
	1. The authors need to mention the space and time complexity of thier 
           hybrid simulator to give an idea on the cost and compare against 
           existing similar simulators.

Authors' comment:
This is our current research and we hope to publish our findings at an
appropriate venue.

	2. The authors need to use the simulator to provide news insights on 
           TCP behaviour that other simulatores (such as ns-2) fail to show.

Authors' comment:
The reviewer has made an important observation. However, due to lack of space, 
we were not able to comment/give any analytical treatment of our work.


// other comments.
//
	3. The motivation for this work is not explicit or made strong. How 
           does the suggested simulation model differ from the existing. The 
           authors have mentioned that the new simulator include the effects 
           of propagation, etc....
	4. But they need to mention the significance of the new features added 
           in the new hybrid simulator. This will help to make the contribution 
           of this paper clearer.

Authors' comment:
    We have added main results, which also give motivation and a summary of
    our contributions in the abstract section, to incorporate this comment.

Review 3.: 
	1. The paper lacks originality.
	It makes minor modification to perform the hybrid simulation based on 
	reference [10] by introducing a time-stepped approach in reference [8,9]
	2. The model described in section III does not explicitly clarify the 
 	contribution of the authors and the related work.

	3. Some of the important claims need to be justified. For example,
 	   In the last paragraph of section I, the authors claims the 
           contribution of the paper are:
		1. Explicitly model the propagation delay.
		   However, the model described in section III does not show 
                   the difference through formula (3)-(5). Compared with 
                   formula (7)-(9)

Authors' comment:
The reviewer has made an interesting comment. In our approach, we take a 
fixed-time step at the end of which we recompute sources and queues. Unlike
Bohacek's work (where propagation delays are implicit - modeled by the
simulation environment *not* by the model itself), we have done this 
explicitely - by recomputation of variables at the end of time-step. Hence
the term explicitly model of propagation delay - since our model addresses
it. 

		2. Provide a more mathematically accurate hybrid system model 
                   of the TCP protocol.
	4. In reference [10], Bohacek already considered the bandwidth of the 
           out-bound link, arrival rate and departure rate. Queue size is just 
           used to easily classify the states. Why formula (9) is more accurate
 	   than Bohacek’s approach? Still needs further discussion.

Author's comment:
Due to lack of space, we have not been able to showcase the entire
mathematical model.

	5. There are also some reference errors. For example, In the last 
        paragraph of section I, the reference [11] does not contain any work 
        of Bohacek, et. al.
Author's comment:
The reference 11 is for hybrid systems reference, and not Bohacek's work.
In the same section there is a reference for Bohacek's work, [10].


Review 4.:
	1. Paper is very hard to read by non specialists.

Authors' comments:
Since we have used hybrid systems (mix of continuous and discrete), we
have to provide the mathematical formulation of our approach to
describe the novel aspects. This probably makes the paper a bit
difficult for non specialists.