Category Multicast

This is the capstone. If you have worked through the previous articles, you now know how every multicast protocol operates at the packet level. You can configure PIM, troubleshoot RPF failures, & set up any RP mechanism. But knowing how…

This article is different from the others. I am not going to teach you a protocol from scratch. Instead, I am going to hand you a broken network & ask you to fix it. Five different multicast failures, all pre-staged…

If you have been following this series, you now understand multicast deeply at a campus & enterprise level. Now let us talk about where multicast takes on a completely different role — the Data Center. In a modern DC fabric…

Let me tell you about the single most frustrating multicast troubleshooting session I ever had. It was a campus network running IPTV for about 200 rooms, PIM-SM, RP properly configured, IGMP groups all healthy. Everything worked perfectly from one source,…

If PIM Sparse Mode is the engine of multicast, the RP is the steering wheel. Get the RP wrong & your entire multicast domain collapses — new receivers cannot join, new sources cannot register, & the only thing that keeps…

If there is one protocol you absolutely must understand inside-out to call yourself a multicast engineer, it is PIM Sparse Mode. This is the protocol running behind every IPTV deployment, every Bloomberg market data feed, every Webex multicast stream, &…

I remember the first time I configured PIM Dense Mode in a lab. I thought it would be the simple, straightforward option — no RP to deal with, no rendezvous point shenanigans, just “send traffic everywhere & let routers sort…

If I had a dollar for every time someone told me “multicast is working, so what is the problem?” while their access switch was flooding multicast traffic out every single port like a broadcast storm, I could probably retire. The…

Here is something that catches a lot of engineers off-guard. They configure PIM, set up the RP, multicast “works,” & they move on. Then six months later, a receiver stops getting traffic & nobody can figure out why. Nine times…

Let me tell you something that took me an embarrassing amount of time to truly appreciate early in my career. I understood multicast conceptually  “send once, deliver to many”  but I never actually saw unicast fail until I sat in…