[c-nsp] Multicast group but no traffic

[Vitkovský Adam]

Well talking multicast you need to specify what route (state) are you seeing as well as which PIM mode are you running across your WAN. 

So you see either just the (*,g) state -means the designated router for the LAN segment as displayed by the cmd: " sh ip pim int" (Nexus) has translated the IGMP membership reports(igmp joins) into PIM Joins and sent them towards the RP (would be good to know which of your routers is RP). 
You might actually be getting the stream if PIM is running in BIDIR or Dense mode -the stream can be checked via "sh ip mroute active". 

Or you see also the (s,g) state -means the RP has an active source for the previously requested group or has send a register message towards the source. 
In either case as the source starts to send traffic down the shared tree (*,g) this is how the Nexus will learn about the source of the source for the group and can join source tree by sending PIM Join towards the Source (s,g) state.  -the stream can be checked via "sh ip mroute active". 


adam
> -----Original Message-----
> From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
> Scott Voll
> Sent: Friday, May 09, 2014 9:38 PM
> To: Phil Mayers
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] Multicast group but no traffic
> 
> VLC Player with TTL 10.  Connected to 3560 to Nexus 55xx with Layer 3.
>  connection to 3845 over WAN to remote site, to 2911 to 2960 layer 2 switch.
> 
> I can see on Nexus, 3845 and 2911 the IP Mroute for the group I'm sending.
>  Via a packet capture I can see the multicast local to the Nexus on multiple
> vlan's
> 
> I can see on the 2960 the groups and interfaces.  But a wire capture on the
> local PC all I see is the join packets, no traffic.
> 
> Other ideas?
> 
> Scott
> 
> 
> On Fri, May 9, 2014 at 11:28 AM, Phil Mayers
> <p.mayers at imperial.ac.uk>wrote:
> 
> > On 09/05/2014 18:53, Scott Voll wrote:
> >
> >> I'm working on rolling out my Multicast across my WAN.
> >>
> >> I can see the Multicast group on the WAN router and I can see it on
> >> the switch interface, but I'm not getting the traffic.  What should I
> >> be looking at?
> >>
> >
> > That's a bit vague. John has made some good suggestions but you'd get
> > more specific answers if you can specify the topology in detail.
> >
> > How are you determining you're not "seeing" the traffic? No video at
> > receiver app? If so, check again with tcpdump/wireshark and look out
> > for software firewalls. That one catches me a lot - I always forget
> > iptables on my laptop :o(
> >
> > "sh ip mr active" and "sh ip mr count" are useful at L3 hops. L2 hops
> > are far harder to debug, unfortunately.
> >
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