ip pim sparse-dense-mode

Answered Question
Jun 11th, 2007

Exactly what does this do?

ip pim sparse-dense-mode

Can someone point me to the link that would have the best documentation on these cisco commands.

Thanks!

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Correct Answer by ariela about 6 years 10 months ago

Hi,

The 'ip pim sparse-dense mode' command enables PIM to operate in sparse or dense mode, depending on the multicast group. When you enable sparse-dense mode, the interface is treated as dense mode if the multicast group is in dense mode. If the group is in sparse mode, the interface is treated in sparse mode. You must have a rendezvous point (RP) if the interface is in sparse-dense mode and you want to treat the group as a sparse group.

The RP could be configured:

- manually (ip pim rp-address)

- dinamically with AutoRP (Cisco solution, it works in sparse-dense mode, or in sparse-mode with 'autorp listener' feature)

- dinamically with BSR code (standard, it works in sparse mode)

for more informations:

http://www.cisco.com/en/US/tech/tk828/technologies_white_paper09186a00800d6b63.shtml

HTH

Andrea

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Correct Answer
ariela Mon, 06/11/2007 - 06:45

Hi,

The 'ip pim sparse-dense mode' command enables PIM to operate in sparse or dense mode, depending on the multicast group. When you enable sparse-dense mode, the interface is treated as dense mode if the multicast group is in dense mode. If the group is in sparse mode, the interface is treated in sparse mode. You must have a rendezvous point (RP) if the interface is in sparse-dense mode and you want to treat the group as a sparse group.

The RP could be configured:

- manually (ip pim rp-address)

- dinamically with AutoRP (Cisco solution, it works in sparse-dense mode, or in sparse-mode with 'autorp listener' feature)

- dinamically with BSR code (standard, it works in sparse mode)

for more informations:

http://www.cisco.com/en/US/tech/tk828/technologies_white_paper09186a00800d6b63.shtml

HTH

Andrea

satish6541 Wed, 12/18/2013 - 03:37

Hi ,

My question regarding Pim sparse-dense mode is , when an RP configuration is not available for a particular group, it would be using pim dense-mode. What if an RP is configured for that particular group when there is a multicast route available(through dense-mode) ,Is the route calculation done again using Sparse mode?

Also if a particular group is configured with RP and route is calculated using Sparse mode , what if the RP address is deleted , should the switch  revert back to dense mode states ?

Thanks & Regards,

Sebastian Fernandez Wed, 12/18/2013 - 05:42

Hi Mohan,

If the mroute is already populated through a dense mode and new RP is configured, there is no change made to the existing mroute until it times out. Any dense group traffic will flow through dense mroute, no convergence will occur unless mroute is cleared.

Rgds,

satish6541 Tue, 01/14/2014 - 20:08

Hi Sebastian,

Thanks for your reply. From some materials, I was able to understand that Sparse-dense mode is mainly used with Auto-RP, wherein all the groups are considered DM at first, and when the RP is know in all routers, it converges for Sparse Mode.

My question here is, how does sparse-dense mode behave in case of dynamic RP configuration with BSR routers.

There will be a time delay in the network before the RP is spread across all the routers from the BSR. To be exact some routers will have RP configuration , and some may not have. How will this scenario span out ? some routers may act as SM and some as DM for a specific group. Wouldnt this lead to misbehaviour in the network ?

Thanks & Regards, 

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Posted June 11, 2007 at 5:59 AM
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