Re: pim assert and DR.. Is it really just metric?

This is an expected behavior for this topology.

Since R4 is the inly client R2 and R3 know of at all, only a DR will send PIM join ip the tree for the traffic coming from R5. You will not observe any PIM asserts, as there is no duplicate traffic.

When R1 is acting as a source it doesn't care about any joins and sends traffic out all PIM enabled interfaces, hence the duplicate traffic on R3 and R4.

It you want to observe assert in this topology, you'll need clients on R2's and R3's interfaces other than the shared one. In other words, you need to make sure they both have. Copy of the traffic.

--
Marko Milivojevic - CCIE #18427 (SP R&S)
Senior CCIE Instructor - IPexpert
:: This message was sent from a mobile device. I apologize for errors and brevity. ::
On Jan 24, 2013, at 21:08, ccie99999 <ccie99999_at_gmail.com> wrote:
> Thanks for your reply guys.
> 
> As Brian suggested I put a R5 behind R1 so topology is:
> 
> R5-R1-(R2/R3)-R4
> 
> R1 is rp (statically defined everywhere)
> R5 is source via phisical interface
> R4 is client on phisical interface face to R2/R3
> R2/R3 are in multiaccess network
> 
> strange enough now that whenever I source traffic from R1 (with ping to
> 239.1.1.1) I got reply and I see an assert message/election (like yesterday
> R2 loses:)
> PIM(0): Assert metric to source 10.0.13.1 is [0/0]
> PIM(0): We lose, our metric [110/20]
> 
> whenever I ping from R5 I have replies but I don't see any assert
> messages.. (starting from clean situation: clear ip mrout * etc)
> This is not the first time I see this behavior in my lab.
> Is there any particular reason?
> 
> thanks
> 
> 
> 
> 
> On Thu, Jan 24, 2013 at 3:44 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:
> 
>> Your issue is that R3 is not asserting for 1.1.1.1, it's asserting for
>> 10.0.13.1:
>> 
>> *Jan 24 08:22:17.631: PIM(0): Received v2 Assert on FastEthernet1/1 from
>> 10.0.234.3
>> *Jan 24 08:22:17.635: PIM(0): Assert metric to source 10.0.13.1 is [0/0]
>> *Jan 24 08:22:17.639: PIM(0): We lose, our metric [110/2]
>> *Jan 24 08:22:17.639: PIM(0): Prune FastEthernet1/1/239.1.1.1 from (
>> 10.0.13.1/32, 239.1.1.1)
>> 
>> R3 advertises [0/0] because 10.0.13.1 is on the directly connected link,
>> hence a metric and distance of zero.
>> 
>> Look at the "show ip mroute 239.1.1.1" on R2, R3, and R4 and see what the
>> (S,G) entry is.  Based on this debug I'm going to say that it is
>> (10.0.13.1, 239.1.1.1), and not the (1.1.1.1, 239.1.1.1) that you're trying
>> to generate.  The reason why is that R1 isn't really sourcing the traffic
>> from 1.1.1.1 even though you tell it to in your ping.  A better test would
>> be to put another router behind R1 and source the traffic from that
>> interface.
>> 
>> Let me know how it works out.
>> 
>> 
>> 
>> HTH,
>> 
>> Brian McGahan, CCIE #8593 (R&S/SP/Security)
>> bmcgahan_at_INE.com
>> 
>> Internetwork Expert, Inc.
>> http://www.INE.com
>> 
>> 
>> 
>> -----Original Message-----
>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
>> ccie99999
>> Sent: Thursday, January 24, 2013 4:10 AM
>> To: Cisco certification
>> Subject: pim assert and DR.. Is it really just metric?
>> 
>> guys, I've just spent the night trying to figure out what the hell was
>> happening with my multicast lab and a specific task of my wb.
>> 
>> I've asked some help here and there and another kind ccie candidate tried
>> to help me.
>> To make the story short and easy, everything started from a basic lab
>> where I was trying to look at the assert message and where we have seen
>> some unexpected behavior.
>> 
>> I would like to have some opinion on this. Everything is explained on this
>> blog post just written  http://mellowd.co.uk/ccie/?p=3250
>> 
>> If someone could take a look it would be nice.
>> 
>> thanks for your help.
>> 
>> 
>> --
>> @ccie99999
>> https://twitter.com/ccie99999
>> 
>> 
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> 
> 
> -- 
> @ccie99999
> https://twitter.com/ccie99999
> 
> 
> Blogs and organic groups at http://www.ccie.net
> 
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