https://songkou.github.io/tags/pim/Recent content in PIM on Council of ElrondHugoenMon, 20 Nov 2023 12:00:00 +0800https://songkou.github.io/posts/pim-sparse-mode-detailed/Mon, 20 Nov 2023 12:00:00 +0800https://songkou.github.io/posts/pim-sparse-mode-detailed/<p>A step-by-step walk through the PIM Sparse Mode (PIM-SM) control plane — from a receiver&rsquo;s IGMP report through shared-tree construction, source registration, the native source tree, and the optional shortest-path-tree switchover — then how to make the Rendezvous Point redundant with Anycast RP. For the Designated Router versus Assert election and multicast-ECMP behavior, see the companion post <a href="https://songkou.github.io/posts/pim-dr-assert-multicast-ecmp/">PIM DR, Assert, and Multicast ECMP</a>.</p> <h2 id="1-overview">1. Overview</h2> <p>Protocol Independent Multicast Sparse Mode (PIM-SM) builds multicast distribution trees only where receivers explicitly request traffic. It is intended for networks where multicast receivers are sparsely distributed.</p>https://songkou.github.io/posts/pim-dr-assert-multicast-ecmp/Sat, 11 Nov 2023 12:00:00 +0800https://songkou.github.io/posts/pim-dr-assert-multicast-ecmp/<p>Several questions come up whenever two PIM routers share a receiver VLAN over equal-cost paths: if the <strong>DR</strong> and the <strong>Assert winner</strong> are different routers, which one forwards the multicast? Does a single stream ever spread its packets across both paths? If you change nothing, do 500 streams split evenly across the two routers—or does that take configuration? And what changes if the switch becomes a Layer 3 router? This post works through each, with the underlying PIM mechanics and a clear line between what the standards mandate and what is vendor-specific.</p>