[zeromq-dev] UDP support

Martin Sustrik sustrik at 250bpm.com
Mon Feb 1 15:25:05 CET 2010


> I have tried to set the transmission rate with zmq_setsockopt(). But 
> there must something be wrong in the docs ... when I specify the opt 
> length with sizeof(uint64_t) the zmq_setsockopt() call returns an error 
> value. sizeof(int) is working ...

Strange. The code tests the optlen for equlity with sizeof (int64_t). 
I'll have a look at this.

> that means also that the multicast 
> example isn't correct. You should also correct the examples of the 
> connection string in the docs of zmq_udp ... the first colon must be a 
> semicolon.

Which multicast example? The one on the website


seems to be OK.

> However ... why do I have to wait 10sec at the site of the sender before 
> I can call e.g. zmq_msg_close?

Because of rate limiting, see below.

> IMHO .. there must be a limitation in the PGM protocol. It seems so that 
> it can't handle a burst of messages if the overall volume is more then 
> ~100kB. Under this level all is working well and really fast. No 
> problems with the tcp transmission!

Hm. Are you sure the multicast is what you want? Rate limiting is pretty 
important for multicast transports. Otherwise you would just overload 
the network. Given the one-to-many nature of the transmission TCP-like 
congestion control is not an option.


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