From: Ramanpreet Singh (sikandar.raman@gmail.com)
Date: Wed Feb 25 2009 - 16:13:07 ARST
Nadeem,
What Pavel is saying make sense to me. here is the cisco doc
PIM Dense Mode (PIM-DM)
PIM-DM uses a push model to flood multicast traffic to every corner
of the network. This is a brute force method for delivering data to
the receivers but in certain applications this might be an efficient
mechanism if there are active receivers on every subnet in the
network.
PIM-DM initially floods multicast traffic throughout the network.
Routers that do not have any downstream neighbors prune back the
unwanted traffic. This process repeats every three minutes.
The flood and prune mechanism is how the routers accumulate their
state informationby receiving the data stream. These data streams
contain the source and group information so that downstream routers
can build up their multicast forwarding table. PIM-DM can only support
source trees(S,G) entries. It cannot be used to build a shared
distribution tree.
PIM Sparse Mode (PIM-SM)
PIM-SM uses a pull model to deliver multicast traffic. Only network
segments that have active receivers which have explicitly requested
the data will be forwarded the traffic. PIM-SM is defined in RFC 2362.
source:-http://www.cisco.com/en/US/tech/tk828/tech_brief09186a00800a4415.html
Thanks,
Raman
On 2/25/09, Nadeem Ansari <nadeem.ansari574@gmail.com> wrote:
> Hi Pavel,
>
> There are no terms called "Push" and "Pull" documented any where in RFC for
> PIM-SM :),It feels good for a person own understanding or to make terms
> simple
> Actually better if we called it as Explicit Join (Pull) and Implicit Join
> (Push), thats the basic buddy. :)
>
> Regards
> Nadeem
> On Wed, Feb 25, 2009 at 7:46 PM, Pavel Bykov <slidersv@gmail.com> wrote:
>
>> "Push" and "Pull" are correct terms.
>> "sparse-dense-mode" is not a PIM method, but an interface operating mode.
>> It's something different. A loose analogy would be enabling RIP and OSPF
>> on
>> the same interface - if there is no OSPF route, a RIP route would be used.
>>
>> Same for multicast. There is a "Sparse mode PIM" that uses pull model,
>> sometimes needs RP, but not always (extensions like SSM or concepts like
>> Phantom RP remove this need). It does not forcefully flood data - that's
>> what makes it PULL.
>>
>> Then there is "PIM dense mode" that pushes data - but again, it's a
>> multicast routing protocol, it is not an interface mode you are referring
>> to.
>>
>>
>> And Nadeem... I really hope you're kidding, otherwise you need to get back
>> to basics.
>>
>>
>> On Wed, Feb 25, 2009 at 2:14 PM, Modular <modulartx@gmail.com> wrote:
>>
>> > Anthony Sequeira had a list of example "open ended questions".... of of
>> > which was:
>> >
>> > "which multicast PIM method uses a push and pull approach"???
>> >
>> > What's the correct answer???
>> >
>> > "sparse-dense-mode" -Which technically can do both. (Based on whether
>> > the RP is known or not.
>> >
>> > "sparse-mode" -the source pushes to the RP, while the client pulls from
>> > the
>> > RP.
>> >
>> >
>> > Thanks,
>> > Mod...
>> >
>> >
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>> >
>> >
>> >
>> >
>> >
>> >
>>
>>
>> --
>> Pavel Bykov
>> ----------------
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