IGMP Snooping and VLC player

[Music] so I was having some fun with VLC and VLC for many of you who used it as a it's to do everything - Oh plays music and it also does multi casting and I was playing with the multi casting option I went to the wizard for streaming and transcoding I said sure I want to stream my content to the network in my home I said next I picked a file I like to send out I said next I said I want to be UDP multicast go ahead and use this group to 24 1.2.3 looks good and then it says do you want to transcode it no Paula sent it as it is and then I clicked on the encapsulation format which is defaults to this for the default settings I had click on next I can name it the TTL how many router hops it'll go over and then local play black yes or no and then click Next gives me a confirmation and then it goes for it now check this out multicast is a lot of fun however this multicast address once it's set into your network in a switched environment what is your switch going to do with that I guess the first question to ask is what exactly is the layer 2 address associated with that so I got out a protocol analyzer and I looked at it I get the VLC stuff out of the way the destination multicast address for that multicast group of 224 1.2 to 3 is right here it's 0 1 0 0 5 e no shock there multicast and then 0 1 0 2 0 3 now what's the switch my dear switch here what's it gonna do when it receives that frame on a port let's say it's coming in from another network which it was in my case it's being forwarded through a multicast router it's being put in this port was the switch gonna do with it well the switch is gonna say I don't know where that destination MAC address lives by default I'm just gonna forward it to every other port because it's an unknown and unfortunately that is wasted bandwidth so everybody's gonna receive those bits every day everybody's gonna look at the layer 2 frames and only the members of that group will then continue to D in caps like that wouldn't it be great if there was a way we could train the switch to get smart and say you know what pay attention to the multicast group and only forward those multicast frames to the devices who are participating in multicast meaning they're either there a pin device they've sent register messages or they've sent member messages with IGMP make sure you pay attention to all that snoop in on that eavesdrop and don't waste people's bandwidth and time who don't need the bits and that's exactly what the feature of igmp snooping does for a living so here's what I did let me bring in a switch now this is not the same switch this is a 48 port 35 60 and here we have looks like a 1 2 3 4 5 6 12 port well maybe 13 port 3560 a small one power over ethernet so on my switch what is this I said well let me see how hard it is to enable this igmp snooping and have this guy start getting smart and it wasn't very hard at all in fact all I do is go to global config and type in IP a GMP snooping enter and then I had to turn on the feature for VLAN 1 that's where all my stuff is that's it doctor that shows over that's it though what this is doing now my switch is now gonna start filtering and not bother sending multicast traffic to ports that don't have any need for it so just that alone this is gonna eavesdrop it's gonna figure out where my router running PIM are it's gonna figure out where my clients who sent a G&P messages in the network and I can verify that with a couple quick show commands me to show IP a GMP snooping and then we'll we can start with that one that's good and then we could do a question mark and see if there's other options here there's groups and they bring this over a little bit further to the right or to the left so you can see as weather says it shows me I've got 2 24 1.2.3 2 25 2004 to 3 and 2 26 4 top 5.3 and here's the ports involved if I want to see which of those devices are routers I could do a show I pee igmp snooping let's look at the question mark again am router that'll do it and that's gonna show me my two devices I do have two routers on VLAN one they're both doing multicast routing and that would mean that this port 21 has joined three separate groups so that's why he's showing up so my switch in this case this 48 ports which is now filtering on ports that don't need the multicast data and forwarding where it needs to and that my friends is how you set up a GMP snooping [Music] [Applause] [Music]

Channel: Keith Barker

Views: 90,076

Keywords: multicast, VLC, IGMP snooping, cisco, keith6783

Id: 5Ovh9dUsAWU

Length: 5min 20sec (320 seconds)

Published: Wed Jul 18 2012