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Posts Tagged ‘multicast’

Basic Multicast part 2 – PIM Sparse Mode – Static RP

August 5, 2012 4 comments

This is the second part of my previous topic about Multicast. This time I will demonstrate how PIM Sparse Mode works based on the same topology as the previous post.

Let´s consider the following topology:

Source: The multicast source 150.1.0.4 will be sending to multicast group 239.10.10.10 which is part of the administratively scoped addresses assigned by IANA which is for use in private multicast domains, much like the IP unicast range defined in RFC 1918.

 RP: The RP is R4 with IP: 4.4.4.4

 IGP: The IGP used is EIGRP

 Platform/IOS: Cisco 2691/12.4(15)T11 Adv IP services

 As PIM Sparse Mode is a much wider topic than PIM Dense Mode I will start to talk about PIM Sparse Mode with static RP, than Auto-RP, Auto-RP listener and finally PIM BSR.

PIM Sparse Mode is based on the “pull model” or “explicit join” which use a combination of both a shared tree and a source-based tree. The RP is making the connection between the shared-tree (tree build down the Multicast receivers) and the source-based tree (tree built up to the source).

PIM Sparse Mode uses (*,G) entries to forward Multicast traffic unlike PIM Dense Mode. So the key difference between PIM Sparse Mode and PIM Dense Mode is that PIM Sparse Mode the forwarding state in the router is set up as a result of an explicit “join” where in PIM DM (PIM Dense Mode) the forwarding state is set up upon arrival of multicast traffic.

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Basic Multicast part 1 – PIM Dense Mode

March 16, 2012 14 comments

I would like to share some basic Multicast examples. As this topic is quite wide I will make different posts. This first post will talk about PIM Dense Mode. The next post will cover topics such as PIM Sparse Mode, Auto-RP and PIM BSR.

 Let´s consider the following topology:

Source: The multicast source 150.1.0.4 will be sending to multicast group 239.10.10.10 which is part of the administratively scoped addresses assigned by IANA which is for use in private multicast domains, much like the IP unicast range defined in RFC 1918.

IGP: The IGP used is EIGRP

Platform/IOS: Cisco 2691/12.4(15)T11 Adv IP services

 Let ´s start with Dense Mode. PIM Dense Mode is based on the “push” or “implicit join” model where Multicast traffic is flooded throughout the entire multicast domain without the receivers needing to join the specific multicast group being flooded. So PIM Dense Mode is not really scalable and is only suitable for small multicast implementations. The reason of that is the flooding and the (S,G) state creation for every source/group.

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