how i add deadline information to one flow?

[Huangchengyuan Ryan]

I want to simulate a application attached dealine,and use tcp protocol. What i want to analyse is whether a flow can be completed in a required deadline added by the application.

So how i can add deadline information to a packet, is there a similar example i can refer to ? 

[Tommaso Pecorella]

Hi,

TCP is a strem protocol. The application is (and must be) transparent to what is sent by TCP (the TCP packet size and so on).

As a consequence, there's a huge logical issue in what you are asking. Clarify yourself, come out with an acceptable idea and then feel free to ask.

Have fun,

T.

[Huangchengyuan Ryan]

Thanks for your reply!

Actually, i plan to add a deadline information,such as 50ms, to the tcp option.It minuses as time go by.When the deadline goes down to zero,the flow is marked as failure.However,i am new to ns3.I am not sure it is feasible, is there a similar example i can refer to ?

在 2015年5月7日星期四 UTC+8下午1:16:57，Tommaso Pecorella写道：

[Tommaso Pecorella]

Hi,

perhaps it's a language issue. However, as you explained it, it's not feasible. It's not an ns-3 limitation, it's that you'll never be able to implement such a thing for real (in ns-3 or in a linux kernel).

I know where you want to go. It's the (infamous) streaming over TCP problem. The point is: streaming over TCP is a blasphemy per-se. However, if someone wants to still be damned for the eternity (be my guest), you have to adapt yourself to the situation. TCP is end-to-end, intermediate nodes will not read it (or its options). Well, they shouldn't at least.

Deadlines: 50ms (as an example) means nothing. Nodes doesn't share a common clock in real systems. Timeout are way more complex.

Summarizing: first design your system such as it could be implemented in a real network. At that point you'll be able to simulate it.

Have fun,

T.