[Openais] Re: [Linux-cluster] new userland cman

[Lon Hohberger]

On Mon, 2005-10-03 at 08:10 +0100, Patrick Caulfield wrote:

> >>neutral
> >>-------
> >>- Always uses multicast (no broadcast). A default multicast address is supplied
> >>if none is given
> > 
> > 
> > If broadcast is important, which I guess it may be, we can pretty easily
> > add this support...
> > 
> 
> I was going to look into this but I doubt its really worth it. It's just any
> extra complication and will only apply to IPv4 anyway.

I think broadcast is quite important, actually - although I also think
that it should *not* be the default.

Multicast doesn't always work very well (in practice) on existing
networks, and works poorly (if at all) over things like crossover
ethernet cables and hub-based private networks.  You know, the cheap
stuff hackers use in their houses to play with cluster software ;)

Broadcast is far more likely to work out of the box in the above cases,
and isn't hard to implement (... actually, it's easier than multicast).

Also, IPv6 isn't what I'd call "mainstream" just yet, so supporting all
the hacks we can with IPv4 isn't necessarily a bad thing ;)

-- Lon