WiFi Assert error : cond="now - m_lastRx.start <= GetSifs()

[George]

Hello,

Please see the attached back traces for the WiFi assert ocuring in channel-access-manager.cc.

This error occurs more often when I try to simulate networks with 20+ stations. Using 11.ax WiFi standard with Indoor mixed office channel.

Did anyone encountered this error? I would really appreciate some help with this since it prevents me to further continue my research.

Thank you.

best regards,

George

[Tommaso Pecorella]

Hi,

if you believe it's a bug please report it in our tracker (https://gitlab.com/nsnam/ns-3-dev/-/issues). Moreover, an example script showing the error would be helpful in tracking down the issue.

T.

[George]

Hi Tom,

There is also an error that occurs at high(compared to what I usually simulate) number of STAs in the channel access manager. I have to replicated again in --gdb.

Regarding support for these possible bugs, where you would like me to send the code I'm using?

Thank you!

best regards,

George

[Tommaso Pecorella]

Please report any bug in our tracker - it's far easier, and include (if possible) a script to show it.

Thanks

[George]

Sure, I will send those details in the tracker. Thank you.

[Xueqing Zhou]

Hi George, I met the same problem. Just with 5 STA. Did you find some way to solve it? Thanks!

assert failed. cond="now - m_lastRx.start <= GetSifs()", +4.096188681s 3 file=/home/ubuntu/ns-3-dev/src/wifi/model/channel-access-manager.cc, line=685
terminate called without an active exception

[George]

No, I have not solved the problem.
I have opened an issue on the bug tracker but have not received a response yet. 
You can follow updates here:

https://gitlab.com/nsnam/ns-3-dev/-/issues/862

[George]

Hi Tommaso,

I have opened an issue here :https://gitlab.com/nsnam/ns-3-dev/-/issues/862

However, I added a .txt that can be copied and pasted that will run the necessary repositories and the given example. Do you think that is too much and I should aim to replicate the error in some other way? Thank you!

[igs...@gmail.com]

"assert failed. cond="now - m_lastRx.start <= GetSifs()", +92.003919739s 7 file=../src/wifi/model/channel-access-manager.cc, line=685"

Receiving the same error while trying to use 802.11n MAC in  Adhoc mode in a MANET scenario of 40 nodes.
In fact, the above 'assert failed'  event occurs while trying to increase simultaneous traffic flows from different sources and sinks.

I mean, if the number of traffic flow is set as 2 - the simulation works good.

If we increase the number of traffic flow is set as 3 - the simulation breaks with the above message. (but strangely, sometimes it is working good if the traffic flow is set as 4)

I have tested it with ns3.37. I may try the same with the latest dev version of ns-3 and report again.

Charles Pandian.

[Tommaso Pecorella]

Hi Charles,

yes, testing on ns-3-dev is important, as we might have already fixed the bug. If it's not fixed, any way to narrow it is welcome - and by "narrow it" I mean the smallest possible simulation, with the less modules used as possible.

Thanks !

[igs...@gmail.com]

Update :

As mentioned by Tommaso Pecorella, the issue automatically resolved while using dev version of ns-3.
Thank you,  Tommaso.

Charles Pandian

[Tommaso Pecorella]

Hi Charles,

I'm happy that the issue is fixed in ns-3-dev. Shall we close the issue in the tracker?

Thanks

[Charles Pandian]

Shall we close the issue in the tracker?

Yes. 

Charles Pandian,

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[George]

Hello,

I am sorry for the confusion. The issue I have opened (if you're talking about this issue https://gitlab.com/nsnam/ns-3-dev/-/issues/862) initially contained the above assert but now I have resumed the issue to a main assert that was more consistent. 
The aseert "now - m_lastRx.start <= GetSifs()  I managed to fix/or make it not happen by using lower values for BE_MaxAmpduSize and BE_MaxAmsduSize.

However, the issue now after I edited the post, only refers to an Assert from the MAC layer that happens when a Re-association request is done but there is no BSSID returned...I have attached a script that runs the WiFi simulation scenario with the error occurring there. So please do not close that issue. 

Thank you!

[George]

I am new to this way of working with open-source simulators and sharing this sort of issue with the community. 
In the future, I will aim to always resume to only one bug that I get whenever I open an issue so I don't create any sort of confusions again. 

[Tommaso Pecorella]

Hi,

well, two issues might be related, so it's ok to "chain" them. However, it is far simpler (and more effective) to work on them one at a time.

Anyway, thanks for reporting this, it's important to have feedbacks !

[igs...@gmail.com]

Again, got same assertion failure while using 802.11n with AODV protocol (with 30 ad hoc  nodes and with 5 simultaneous traffic flows)

NS_ASSERT failed, cond="mpdu->IsQueued()", +86.154441728s 26 file=../src/wifi/model/qos-txop.cc, line=671

Just Informing.

Charles Pandian

[Tom Henderson]

Is there an easy way to configure existing example programs to reproduce
this assert?  If not, can you provide a test program to reproduce?

- Tom