From: Pun, Alec CL (Alec.CL.Pun@pccw.com)
Date: Tue Nov 04 2003 - 23:25:36 GMT-3
does that mean a PIM DR doesn't necessary to be the multicast forwarder that
sits along the SPT ?
alec
-----Original Message-----
From: Ozgur Guler (Garanti Teknoloji) [mailto:OzgurG@garanti.com.tr]
Sent: Wednesday, November 05, 2003 7:08 AM
To: bhescock
Cc: ccie2be; Group Study
Subject: RE: Multicast: Querier vs DR
in your case, simply
r2 will be the forwarder,
r3 ethernet is rpf ,so its OIL will be empty,
resulting in an SG state with a P flag.
i admit previous statement of DR in dense mode might be rather broad,
what i meant to say is placement of DR will not be a problem in Dense Mode.
it has actually no use in dense mode.
correct me if i am wrong.
Ozgur
-----Original Message-----
From: bhescock [mailto:bhescock@cisco.com]
Sent: Wednesday, November 05, 2003 12:21 AM
To: Ozgur Guler (Garanti Teknoloji)
Cc: ccie2be; Group Study
Subject: Re: Multicast: Querier vs DR
Ozgur,
Double-check it in the lab with the following topology (sparse or
sparse-dense with rp configured (no one should use
dense mode except in the lab / learning, not recommended)):
source
|
R1
|
R2 (10.1.1.1)
|--------------------receiver
R3 (10.1.1.2)
Just in case the diagram doesn't turn out, the receiver is on a shared
segment between R2 and R3. R2 is the one with the
connection back to the source. The DR is R3. Which router will forward the
traffic to the receiver and why?
Brian
"Ozgur Guler (Garanti Teknoloji)" wrote:
> 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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