All things related to multicast

On Tue, 30 Nov 2004, Stig Venaas wrote:

> On Tue, Nov 30, 2004 at 11:11:36AM -0600, John Kristoff wrote:
> > On Tue, 30 Nov 2004 12:35:26 -0800 (PST)
> > 
> >  wrote:
> > 
> > > Setting DR priority will only set which router win's DR election - 
> > > overriding the normal IP-based election.
> > > 
> > > If you want faster DR failover, tweak down the PIM hello timers. 
> > > This is what is used for a candidate DR to determine that the elected 
> > > DR 
> > > is either alive or dead.
> > 
> > OK, thanks.  I guess that will have to do.  I thought that I might
> > be able to gracefully migrate the DR to another interface, which would
> > magically move PIM state by issuing the associated joins and prunes, but
> > I guess that is just asking for too much magic.  :-)
> 
> Right, so that is another question really. You want to migrate
> manually, while Shep is talking about automatic failover.
> 
> I must say I'm not sure myself what the answer to your question
> is. You're partly talking of failove for receivers. Note that it's
> not always the DR that is the last-hop router.

Doh.. correct. Sorry, I was stuck thinking of redundant/parrallel 
topologies.

Greg
 
> For sending, I think the new DR will immediately start sending PIM
> registers. Also for how people may receive from your sources along
> a SPT, it's the routing (RPF) that determines which of your routers
> it is rooted at, not which is the DR.
> 
> At least I think so. I should read the spec to be sure I don't
> embarass myself, but I don't have time for that right now.
> 
> Hopefully someone will correct me if I'm wrong.
> 
> Stig
>