Archive for March, 2012

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 will be sending to multicast group 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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Basic MPLS

March 5, 2012 8 comments

I would like to share a basic MPLS configuration example where I will explain how MPLS works and what are the different steps in order to configure it. This example is not related to MPLS layer 3 VPNs, this is just going to be the basic underlying logic of how an MPLS tunnel on its own works so I will neither talk about VRF nor MP-BGP which is the VPNv4 address family in order to exchange the customer routes and the MPLS VPN labels.

 Let´s consider the following topology:

PE routers R2 and R4
P router: R3
CE routers R1 and R5

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