[zeromq-dev] PGM: multiple listener behavior?

[Steven McCoy]

On 7 August 2012 13:33, Stuart Levy <salevy at illinois.edu> wrote:

>  Thanks - could you explain a bit more?   In the
> PUB+SUB-on-same-port-on-same-host situation Pierre described - which
> applies to me too - *all* NAKs will be lost, not just some small fraction
> of them, if the SUB socket gets opened before PUB, IIUC.   Does that imply
> that recovery can never happen, regardless of rate limiting, etc.?   I
> don't want the loss of a single multicast packet to mean that the whole
> system will need to be restarted...
>

With multiple senders on the same host on the same PGM session only the
first will receive NAKs due to unicast routing.  It's an OS and protocol
design feature.

I believe with 0MQ only one PGM publisher should ever be active on the
network: a bus topology is not supported by the 0MQ socket.  This is
probably the more pertinent issue that voids a lot of the previous
discussion.


>
> If so, then I don't see how I can use zeromq multicast to create a barrier
> primitive - that I'd be better off just doing all the low-level networking
> myself.  That's a pity, if true.
>

Need a bit more clarification on what you are looking for?  Atomic
multicast?  I think there was a brief mention about this previously.

-- 
Steve-o
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