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

Quite right, multicast ping on IOS is a weird beast to say at least.
You have very little control from which interface it goes out. A
router behind R1 is the way to go, or don't use ping at all.

Now, assert doesn't use only metric. It uses a "composite" value,
which in IOS is formed from AD and the actual metric.

The funny thing is, PIM assert is one of the two situations I can
think of where you could have metrics of different routing protocols
directly compared to make a decision about something.

--
Marko Milivojevic - CCIE #18427 (SP R&S)
Senior CCIE Instructor / Managing Partner - IPexpert
On Thu, Jan 24, 2013 at 7:44 AM, 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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