From: Ozgur Guler (Garanti Teknoloji) (OzgurG@garanti.com.tr)
Date: Tue Nov 04 2003 - 16:53:26 GMT-3
DR role depends if we have the PIM Dense-Mode or PIM Sparse mode.
in Dense mode DR is simply the forwarder.
Dense mode has the Assert Mechanism to elect the DR/Forwarder.
DR Role in sparse-mode is more important.
in sparse mode DR sends the RP-Join/Prunes,register messages towards RP.
Since router will switch to SPT after receiving the first multicast packet,
forwarding router will switch to what you see in the RPF neighbor of the S,G state.
Ozgur
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
bhescock
Sent: Tuesday, November 04, 2003 6:08 PM
To: ccie2be
Cc: Group Study
Subject: Re: Multicast: Querier vs DR
If the other router on the network isn't running pim then this router could be both the DR and IGMP querier. You can
also set the DR priority in newer code as well. However, just because a router is the DR doesn't mean it's the one
that will forward the multicast traffic toward a receiver. The DR only forwards the multicast traffic as a
tiebreaker. I'll leave it up to everyone to figure what the determining factor is to forward the multicast as
homework... ;-)
Brian
ccie2be wrote:
> Thanks for getting back to me.
>
> That being the case, how is it ever possible that both functions, DR and
> Querier, would be on the same router if there's another router on the same
> ethernet? Does it depend on which version of IGMP is running or which mode
> of PIM, Dense or Sparse?
>
> ----- Original Message -----
> From: "bhescock" <bhescock@cisco.com>
> To: "ccie2be" <ccie2be@nyc.rr.com>
> Sent: Tuesday, November 04, 2003 10:27 AM
> Subject: Re: Multicast: Querier vs DR
>
> > DR is the highest ip address on that network, Querier is the lowest ip
> address on that network.
> >
> > ccie2be wrote:
> >
> > > Hi group,
> > >
> > > I'm trying to understand the situation that exists when there are
> multiple PIM
> > > routers on a common Ethernet:
> > >
> > > R1 R2
> > > | |
> > > -----------------
> > > host host
> > >
> > > I know that sometimes the same router will be both the DR and the
> Querier but
> > > at other times these functions will be on different routers.
> > >
> > > Can someone help me out and explain when these functions will be on the
> same
> > > router and when they won't?
> > >
> > > Thanks in advance.
> > >
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