[jbosscache-dev] Re: Anycast

[Manik Surtani]

On 5 Oct 2006, at 13:11, Bela Ban wrote:

>
>
> Manik Surtani wrote:
>> Not the way the RPCDispatcher in JGroups works.  I always pass in  
>> a List of buddies, and usually this list would have 1 element (if  
>> n=1).  Either way, even if n=3 in a 500 node cluster the multicast  
>> is inefficient.
>
> Not worse than TCP: in TCP, we send the *same message* 500 times,  
> one for each node. Everyone discards the message but the 3 who are  
> targetted.
>
> Not a big problem for now, because we usually have small clusters,  
> but something that need fixing in the future.
>
> How the transport delivers a message M to X members of a cluster of  
> size N (where X <= N) is left to the transport.
>
> TCP: here, the transport would probably simply send M to X members.
> UDP: if X is close to N --> multicast M and everyone whose not in  
> the target set X simply discards M. If X is small --> unicast to X
>

Precisely.  Re: UDP, this could even be configurable (i.e., the X:N  
ratio above which a MCAST is triggered)