[j-nsp] Multicast

[Julian Cowley]

On 15 Jul 2005, at 01:03, Pablo Varela wrote:
> On NANOG 27 there was a presentation called "A Methodology for
> Troubleshooting Interdomain IP Multicast" that presents a methodology
> that looks very throrough.
>
> Unfortunately I don't have the RUL but it shouldn't be too hard to  
> find.

Yes, I have to attest this presents a very straightforward way to  
troubleshooting multicast.  We've used it here successfully to fix  
our own multicast feed through Sprint.

http://www.nanog.org/mtg-0302/ppt/caron.pdf

> Pablo
>
> On Fri, 15 Jul 2005 11:53:23 +0100, "Jee Kay" <jeekay at gmail.com> said:
>
>> 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.
>>
>> 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.
>>
>> Thanks in advance,
>> Ras
>>
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>>
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