From: David Lonnie (david.lonnie@gmail.com)
Date: Fri Jul 11 2008 - 13:52:01 ART
Hey.Jason:
yes.you are right.ip pim dm-fallback only works in ip pim sparse-dense mode.
Thanks very much.
This is in DocCD command reference.
Command Default
PIM dense mode fallback is enabled. That is, a multicast group in the
absence of rendezvous point (RP) information will fall to dense
mode,regardless of the interface mode configuration.
And this is in DocCD configuration guid
Step 14
no ip pim dm-fallback
Example:
Router(config)# no ip pim dm-fallback
(Optional) Prevents PIM dense mode fallback.
Configure this command on all routers in a PIM sparse-mode domain.
I have confused with this for a couple of days.
Thanks again.
David
On Sat, Jul 12, 2008 at 12:39 AM, Jason Madsen <madsen.jason@gmail.com>
wrote:
> here's some device output of a device using sparse-mode and then
> sparse-dense-mode with completely default settings:
>
> R0#sho run | s pim
> ip pim sparse-mode
> ip pim sparse-mode
> ip pim sparse-mode
> R0#sho ip multi
> Multicast Routing: enabled
> Multicast Multipath: disabled
> Multicast Route limit: No limit
> Multicast Triggered RPF check: enabled
> *Multicast Fallback group mode: Sparse
> *R0#
>
> R0#sho run | s pim
> ip pim sparse-dense-mode
> ip pim sparse-dense-mode
> ip pim sparse-dense-mode
> R0#sho ip multi
> Multicast Routing: enabled
> Multicast Multipath: disabled
> Multicast Route limit: No limit
> Multicast Triggered RPF check: enabled
> *Multicast Fallback group mode: Dense*
> R0#
>
> Jason
>
> On Fri, Jul 11, 2008 at 10:27 AM, Jason Madsen <madsen.jason@gmail.com>
> wrote:
>
>> I think DM fallback is just for sparse-dense-mode, right?
>>
>> On Fri, Jul 11, 2008 at 10:23 AM, David Lonnie <david.lonnie@gmail.com>
>> wrote:
>>
>>> Hi,experts:
>>> So,is the following conclusion right?
>>>
>>> In a multicast domain,all routers configured with "ip pim
>>> sparse-mode",without RP,C-RP,RP-agent and "ip pim autorp lisntener"
command.
>>> There is nothing different from ip pim dense-mode", is it? because ip pim
>>> dm-fall is enable by default,and will fallback to dense-mode regardless
of
>>> the interface mode configuration.
>>>
>>> correct my if i am wrong.i am really confused.
>>>
>>>
>>> Thanks in advance.
>>>
>>>
>>> On Sat, Jul 12, 2008 at 12:06 AM, Jason Madsen <madsen.jason@gmail.com>
>>> wrote:
>>>
>>>> I believe auto-rp listener uses dense mode only to contact the RP and
>>>> Mapping Agent groups (224.0.0.39 and .40), while DM Fallback allows
>>>> Dense mode (source to client) operation in the event of no RP.
>>>>
>>>> Jason
>>>>
>>>> On Fri, Jul 11, 2008 at 9:54 AM, David Lonnie <david.lonnie@gmail.com>
>>>> wrote:
>>>>
>>>>> Hi,experts:
>>>>> I am confused with these 2 commands.
>>>>> ip pim dm-fallback is enable by default.and it means,it will fallback
>>>>> to
>>>>> dense-mode,regardless of interface mode configuration.
>>>>> if this is right.so why need to configure ip pim autorp listener when
>>>>> using
>>>>> sparse-mode?
>>>>>
>>>>> anybody can clarify for me?
>>>>>
>>>>>
>>>>> Thanks in advance.
>>>>>
>>>>>
>>>>> David
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ip pim autorp listener
>>>>>
>>>>> To cause IP multicast traffic for the two Auto-RP groups 224.0.1.39and
>>>>> 224.0.1.40 to be Protocol Independent Multicast (PIM) dense mode
>>>>> flooded
>>>>> across interfaces operating in PIM sparse mode, use the ip pim autorp
>>>>> listener command in global configuration mode. To disable this feature,
>>>>> use
>>>>> the *no* form of this command.
>>>>>
>>>>> ip pim dm-fallback
>>>>>
>>>>> To enable Protocol Independent Multicast (PIM) dense mode (DM)
>>>>> fallback, use
>>>>> the *ip pim dm-fallback* command in global configuration mode. To
>>>>> prevent
>>>>> PIM dense mode fallback and to block all multicast traffic for groups
>>>>> not
>>>>> specifically configured, use the *no* form of this command.
>>>>>
>>>>> *ip pim dm-fallback *
>>>>>
>>>>> *no ip pim dm-fallback *
>>>>> Syntax Description
>>>>>
>>>>> This command has no arguments or keywords.
>>>>> Command Default
>>>>>
>>>>> PIM dense mode fallback is enabled. That is, a multicast group in the
>>>>> absence of rendezvous point (RP) information will fall to dense mode,
>>>>> regardless of the interface mode configuration.
>>>>>
>>>>>
>>>>> _______________________________________________________________________
>>>>> Subscription information may be found at:
>>>>> http://www.groupstudy.com/list/CCIELab.html
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