[avahi] avahi scalability again

[Robin Perkins]

On 15/05/2009, at 10:56 PM, Lennart Poettering wrote:

> On Fri, 15.05.09 14:11, Olivier R-D (o.r-d at laposte.net) wrote:
>
> Heya,
>
>> I am wondering about using avahi (for service discovery ) for an
>> application, on one lan, but with potentially many computers (maybe  
>> 1000
>> ) and especially many services to publish (maybe 10000). Have some of
>> you tested avahi scalability at that level ?
>
> mDNS has not been designed for such networks.
>
> Apple did some scalability tests with mDNS. And IIRC they say it
> should work up 200 hosts or so. I never did similar tests for Avahi,
> but I'd assume that Avahi isn't too far off, given that we pass the
> Bonjour compat test.
>
> Lennart

Why so many services? If you are publishing that many services then  
surely you are misunderstanding how mDNS is meant to be used. The  
protocol is intended so that you find other hosts on the network using  
the same 'service', something usually common to many hosts eg. web  
traffic or ftp traffic. If it is for a custom application - then only  
the fact that that application is present needs to be advertised - not  
everything that the application can do.

Perhaps using sub-services may be more appropriate - for example I  
wrote a thing for BitTorrent where by each host finds each others by  
looking for _bittorrent._udp and then each individual torrent is a sub- 
service so that matching torrents could be found.

Rob