Lecture 7 - Introduction to PIM Sparse Mode

This is the seventh video of a complete lecture series on IP Multicast and its implementation on both IOS and Junos routers with a focus on CCIE and JNCIE candidate requirements.

In this video we discuss the following topics:

- What is PIM Sparse Mode(Protocol Independent Multicast)
- How does PIM-SM (PIM Sparse Mode) compare to PIM-DM
- How PIM-DM (PIM Dense Mode) uses the pull or explicit-join model
- How do the sources and receivers spawn (S,G) and (*,G) states (SPT, RPT) on FHRs (First Hop Routers) and LHRs (Last Hop Routers)
- What is a Rendezvous Point (RP)
- What functions does an RP (Rendezvous Point) serve in a PIM-SM (PIM Sparse Mode) network
- How do the LHRs build the RPT (Shared Tree) to the RP (Rendezvous Point) via (*,G) Join/Prune message (PIM Join used)
- How do the FHRs inform the RP (Rendezvous Point) about active sources (Active Source Signaling) via PIM Register messages
- How the RP (Rendezvous Point) initiates an on-demand (S,G) SPT Join to the FHRs
- How the PIM Register message is unicast in nature and how it affects the MHRs(Middle Hop Routers)
- How does the RP (Rendezvous Point) bring IP multicast traffic from the FHR (and the sources) to the LHR (and the receivers)
- The IP Multicast states, along with RPF, IIF and OIL interfaces at each state of PIM Sparse Mode Signaling
- The final flow of the IP Multicast traffic with a focus on the (S,G) SPT tree, the (*,G) RPT or Shared Tree and the job of the RP to connect the (S,G) to the (*,G)

[dgfdfgdhggfrh]

The blog doesn't seem to exist anymore but if anybody is maintaining this channel I just want them to know this series incredibly well done and the teacher is excellent.

[jamesdouitsis]

Real great job with explaining the concepts! If only profs taught like you do

[techevangelist]

Great content. Good to have a basic understanding of mcast and sparse mode before watching the video. Then, this video will take you to the next level. Thanks for the upload.

[miguelsegurap]

First serie about Multicast worth watching. Thank you very much for dedicating your time to make videos like this one. Well explained!!

[grimus]

Watched this after reading a guide for a cert. Have to say this was fantastic, very well presented and easy to understand, thank you!

[MGQ]

Great Lectures!!! Great for refreshing for CCIE exam preps.

[sulgawn]

you are the best when it comes to multicasting, I loved the lecture, you made it so simple, can you please make some videos on IPv6 also

[inakundoO]

Super usefull video! Thank you very much for this. When watching your video I came out with the doubt about how R1 knows who the RP is (cause it needs to know the RP's IPto send the unicast message) but I found it quickly doing a google search (All routers are either pre-configured with the RP’s address or can earn it dynamically through Auto-RP or the BSR protocol) By now I will go with the fact all the routers are pre-configured with RP's address. Thanks again!

[lovkeshsharma]

Awesome, this is Well simplified and easily digestible information.

[MS-xqeg]

This is the best series ever. Multicast seemed like black magic before. I know this is an older series, but would you be interested in making videos about bidir, ssm, anycast rp, msdp an so on?

[angelcornelio]

This is a fantastic tutorial organized and very well presented. I am wondering if the presentation slides are available for download.

[apresskidougal]

Really well put together lecture thank you for all your hard work.

[sulgawn]

well presented, too good flow and very well articulated

[VikasGupta-fndb]

Great work .... highly appreciated ...

[andriaginting]

Thanks for your explanation, i have question, why R5 didn't send IGMP register to RP ? why RP much prefer to use R6 as best path to RX ? thanks

[haritar]

"Time to grow up, you're not a normal router anymore". XD
P.S. Great lecture!

[gouthamkondapavuluru]

What if r7 wants to join the multicast tree. It's metric directly to FHR looks shorter than via RP

[mikecondon]

Love this series.

Quick question. Do interfaces remain in the OIL indefinitely after receiving the initial PIM Join? or do downstream routers need to send PIM Joins on a regular interval as a sort of 'keep alive' to remain in the OIL?

[dkoxperiakoziukov]

Thanks for the good explanation.
May I ask you a question?
I have a streamer running on my router OS embedded. The stream is coming over the udp to the multicast address.
When I route the stream to my internal router interface (where PC is connected) VLC is successfully connecting and playing video.
But I need to stream outside and when I rout the stream to the external interface I see the multicast traffic running (with tcpdump), but my VLC on my local PC doesn't connect anymore.
My provider told me they had IGMP and PIM set and running.
Unfortunately I cant check the stream as I have no other available PC. And the VLC on the smartphone doesn't support udp routing.
What I misunderstood? What am I doing wrong?

[yveslouis]

Awesome, thank you - however I would expected the presenter to go a bit further elaborating on SPT switchover - this is when the LHR has the capability to switch to the shortest path Tree and bypass the RP (if the traffic rate hits the threshold set) - building a new branch of the source tree (S, G) SPT. In the example given, there is no shortest path between FHR and LHR, maybe something to update - just a personal thought