Bug 513 – NSC stack loses packet tags

Bug 513 - NSC stack loses packet tags


Summary:	NSC stack loses packet tags

Status:	RESOLVED WONTFIX

Product:	ns-3
Classification:	Unclassified
Component:	internet
Version:	ns-3-dev
Hardware:	All All

Importance:	P5 normal
Assigned To:	Sam Jansen

URL:
Keywords:

Depends on:
Blocks:
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Reported:	2009-02-26 08:26 UTC by Gustavo J. A. M. Carneiro
Modified:	2011-05-18 13:36 UTC (History)
CC List:	1 user (show)

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Description Gustavo J. A. M. Carneiro 2009-02-26 08:26:42 UTC

I have no idea if this is feasible or practical to fix, but I noticed that once packets enter an NSC stack they get stripped of tags.  So, using tags to measure end-to-end delays is not possible when using NSC.

If this is technically impossible or impractical to fix, just mark it WONTFIX, but I had to ask :-)

Comment 1 Rajib Bhattacharjea 2009-02-26 12:52:22 UTC

Sam, can you comment on the feasibility?

Comment 2 Sam Jansen 2009-03-31 18:57:18 UTC

Hmm. Sorry for the late reply here...

I suspect this is fairly difficult to achieve, but not impossible.

The problem is that the actual packet tag data is going to be lost when you do the write() / send() into the stack, and you would then somehow need to match it up with the generated packets we get out of the fake Ethernet driver in the NSC stack.

So yeah, I think we could probably make it work, but:

a) it would be a bit of a hack

b) there would almost certainly be cases that didn't work too well

c) it would probably be a fair bit of work to get right

You can probably imagine I'm not volunteering right now ;)

I think it might be interesting as an experimental feature if somebody really cared, but it seems very low priority.