From: Harindha Fernando (pottaharry@gmail.com)
Date: Tue Jul 08 2008 - 07:33:14 ART
I checked on the lab
show ip multicast
will give u the fallback mode
224.0.1.40 and 224.0.1.39 is for auto-rp rp announce and rp discovery
(mapping agent), it will be in dense mode if you have configured IP PIM
SM-DM but if you have only PIM SM configured on interface then you need ip
pim autorp listener to allow autorp packets to cross sparse mode interfaces.
On Tue, Jul 8, 2008 at 9:46 AM, Joseph Brunner <joe@affirmedsystems.com>
wrote:
> Where did you read that?
>
> even with all sparse-mode interfaces, check 224.0.1.40 and any other group
> with no rp...
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Harindha Fernando
> Sent: Tuesday, July 08, 2008 2:39 AM
> To: John
> Cc: Learn Cisco; ccielab@groupstudy.com
> Subject: Re: Multicast Features
>
> Hi,
>
> If you have configured all the interfaces to PIM-SM then fallback mode will
> be sparse , if you have at least one interface with SM-DM then
> fallback mode will be Dense, by putting no ip pim dm-fallback
> guaranties that fallback will be in Sparse mode.
>
> Rgds,
> Harri
>
> On Tue, Jul 8, 2008 at 3:31 AM, John <jgarrison1@austin.rr.com> wrote:
>
> > spt-threshhold is for source tree. The default is 0 kbs, which means
> that
> > anything over 0 kbs will go to a source tree. no ip pim-dm fallback is
> to
> > prevent, at least sparse-dense mode from falling back to dense mode for
> > unknown groups. In the docs I've seen it used in sparse mode and
> sometimes
> > not. I'm still trying to find a definitive answer on that. Ill probably
> > end up labbing it on friday and then I'll know for sure.
> >
> >
> >
> > "The mind is like a parachute it works best when it's open"
> > ----- Original Message ----- From: "Learn Cisco" <cisco.learn@yahoo.com>
> > To: <ccielab@groupstudy.com>
> > Cc: <cisco.learn@yahoo.com>
> > Sent: Monday, July 07, 2008 5:27 PM
> > Subject: Multicast Features
> >
> >
> >
> > hi, i'm trying to get a better grasp on multicast topics. any feedback
> to
> >> the following questions would be much appreciated:
> >>
> >> 1.) was wondering if anyone can help differentiate between the use of
> "ip
> >> pim spt-threshold infinity" and "no ip pim dm-fallback". they both seem
> to
> >> prevent sparse-dense-mode and/or sparse-mode pim from reverting back to
> a
> >> sourced-tree / shortest-path tree unless I'm missing something.
> >>
> >> 2.) would "ip pim accept-rp auto-rp" be needed along with one of the
> cmds
> >> above to ensure no spt paths form?
> >>
> >> 3.) when would "ip pim accept-rp x.x.x.x x" be used? i guess if i get a
> >> question/requirement that states to have a device accept join/prune
> messages
> >> for an rp i'd know to use this feature, but it seems as though their
> might
> >> be more to this thing???
> >>
> >> 4.) "ip pim autorp listener" is the feature to use when desiring to use
> >> sparse-mode along with auto-rp, right? (without statically assigning
> the
> rp
> >> mapping on all sparse-mode devices)
> >>
> >> thanks in advance for any input,
> >>
> >>
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