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Re: [cf-dev] Problem while using Netem for benchmarking large-large post in Californium
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Hi Abhijan,
I have to admit that the blockwise support in Californium is not the best
maintained and understood area of functionality. We have even been thinking about
re-factoring support for "transparent" blockwise transfers out of Californium's
core stack and maybe into the CoapClient component only. However, I am still
interested in your test case, so it would be helpful to know what you are
actually trying to do and, most importantly, what version of Californium you are
using. If you think that what you experience is a bug, then you might also
consider creating an issue on GitHub [1].
[1] https.//github.com/eclipse/californium
--
Mit freundlichen Grüßen / Best regards
Kai Hudalla
Chief Software Architect
Bosch Software Innovations GmbH
Schöneberger Ufer 89-91
10785 Berlin
GERMANY
www.bosch-si.com
Registered office: Berlin, Register court: Amtsgericht Charlottenburg,
HRB 148411 B;
Executives: Dr.-Ing. Rainer Kallenbach, Michael Hahn
On Mo, 2016-10-17 at 12:39 +0530, Abhijan Bhattacharyya wrote:
> Dear list,
> We are trying to do some bench marking of a typical large-large post scenario
> under different bandwidth and losses. We are using Californium. However, we are
> experiencing an apparently bizarre problem.
>
> We are running the client and server in two VMs and routing the packets through
> a third VM. We are observing the exchanges in Wireshark at both client and
> server ends. The exchanges happen as usual. However, whenever we are
> incorporating loss in the 3rd VM we see the problem.
>
> We are using the following command for incorporating loss in the 3rd VM (this
> one is configured with 2 interfaces)
> sudo tc qdisc add dev eth0 root netem loss <n>%
>
> As soon as the loss is incorporated we see that after exchange of one or two
> blocks (or some time not even a single one) the exchange stalls and the client
> is getting Null pointer exception. Actually, the server is responding, but the
> client is not able to receive the packets and the application layer, rather
> than doing retransmits, is somehow crashing. Is Netem doing something with the
> state machine?
> If anyone has faced this problem or has any idea regarding this may please
> respond.
>
>
>
> Regards
> Abhijan Bhattacharyya
> Associate Consultant
> Scientist, Innovation Lab, Kolkata, India
> Tata Consultancy Services
> Mailto: abhijan.bhattacharyya@xxxxxxx
> Website: http://www.tcs.com
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