[j-nsp] Multicast

[Rafal Szarecki (WA/EPO)]

Jee

be syte that your genetator send packet with TTL greater then 1. Many of aplication like this, including ping automaticaly sets TTL=1 for multuicas destination.

Coments in-line ...

> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net 
> [mailto:juniper-nsp-bounces at puck.nether.net]On Behalf Of Jee Kay
> Sent: Friday, July 15, 2005 12:53 PM
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] Multicast
> 
> 
> I've got a really strange problem with multicast between a pair of
> Junipers. The setup is as follows:
> 
> Traffic Generator -- Juniper1 -- Juniper2 -- Traffic Sink
> 
> The two Junipers see each other as PIM neighbours happily. Juniper1
> seems a PIM Join entry for the Sink, and the output of show pim join
> extensive and show multicast route says it is correctly forwarding the
> multicast traffic out towards Juniper2.
> 
> Juniper2, in turn, has a PIM Join entry correctly showing that traffic
> should be sent towards the sink, aswell as the appropriate IGMP Group
> entry. Show multicast route on this route says no route entries
> matched.
> 
> As far as I can tell from a sniffer between J1 and J2, the multicast
> traffic is genuinely appearing on the link, although a filter on the
> ingress interface on J2 doesn't seem to pick it up.

Are you sure that m-cast for propoer group is _constantly_ send from J1-->J2?
M-cast is "traffic driven" and use timeouts in hevy way, so even in PIM-SM, you can observe that few packet goes over link and then downstream-neighor prunes-out them...

 
> 
> Anyone have any ideas how to go about troubleshooting exactly what's
> happening here? It looks like all the individual components are
> working correctly but there is some key part missing that is causing
> J2 to receive the multicast but not realise that, despite the IGMP
> state, it needs forwarding on.
> 
> For the record, this is all PIM Sparse, J1 is the RP (set as local on
> J1, static on J2), I am using inet.2 for RPF checks (with the
> appropriate rib-groups to distribute OSPF into .0 and .2), have
> interface-routes set to distribute into both tables also. IGMP is
> enabled on all interfaces, version 2. Packet traces show that the sink
> is correctly using IGMPv2. PIM is also enabled on all interfaces, mode
> sparse. The RP address is a secondary IP on lo0 of J1. PIM and IGMP
> are disabled on fxp0.
> 

Check assert status on egress interfaces (J1-->J2 and J2--sink.). (sh pim grop join extensive, sh igmp group ext). I have some trubles with this on LR enviroment.

"configs" and sh "pim join ext" as well as "sh multicst route ext" will be usefull.


> Thanks in advance,
> Ras
> 
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net
> http://puck.nether.net/mailman/listinfo/juniper-nsp
>