[zeromq-dev] Limited UDP Message Size

[Greg Young]

This is correct ... Some things may not accept/forward it.

Beyond that its common for things to get *added to it* thus you want to be
below. Consider a case where its being wrapped (tunneling is a good
example).

Over the internet the maximum completely safe size is even smaller
around 500-600 bytes :O You can usually get above this but +- 1k is about
the limit.


On Sun, Jan 12, 2020 at 4:42 PM Stephan Opfer <opfer at vs.uni-kassel.de>
wrote:

> Ah okay. I read some posts about MTU and fragmentation. So in theory
> 2^16= 65536 Bytes should be possible, but not all nodes will accept such
> large UDP packets and support the fragmentation of it?
>
> FYI: My use case is that of a local network (IOT + Autonomous Robots) and
> increasing the size would help me. :)
> On 12.01.20 13:25, Doron Somech wrote:
>
> We can increase it to around 65,000 bytes, however, large UDP packets
> would probably be dropped when traveling outside your local area network.
> The safe size for the UDP packet to travel outside of the local area
> network is around 500 bytes.
> If you do want to use large UDP packets on your local area network you
> might want to increase the network MTU (jumbo frames) for better delivery.
>
> For example, some AWS instances support 9001 bytes MTU for inter-instance
> communication.
>
>
> On Fri, Jan 10, 2020 at 3:25 PM Stephan Opfer <opfer at vs.uni-kassel.de>
> wrote:
>
>> Hi all,
>>
>> since 2016 there is this issue
>> (https://github.com/zeromq/libzmq/issues/2009) about some limitations of
>> the udp_engine in libzmq.
>>
>> Is it possible that someone at least will increase the "#define
>> MAX_UDP_MSG 8192" in libzmq/src/udp_engine.hpp to some reasonable value?
>> For example "ZMQ_MAX_MSGSZ" from the zmq context option, which is MAX_INT.
>>
>> Maybe, someone could spare some time at the Hackathon... ;-)
>>
>> Greetings,
>>
>>    Stephan
>>
>> --
>> Distributed Systems Research Group
>> Stephan Opfer  T. +49 561 804-6279  F. +49 561 804-6277
>> Univ. Kassel,  FB 16,  Wilhelmshöher Allee 73,  D-34121 Kassel
>> WWW: http://www.uni-kassel.de/go/vs_stephan-opfer/
>>
>> _______________________________________________
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>>
>
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>
> --
> Distributed Systems Research Group
> Stephan Opfer  T. +49 561 804-6279  F. +49 561 804-6277
> Univ. Kassel,  FB 16,  Wilhelmshöher Allee 73,  D-34121 Kassel
> WWW: http://www.uni-kassel.de/go/vs_stephan-opfer/
>
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>


-- 
Studying for the Turing test
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