Re: RPF Query!!!!!!!!!!

I just answered how your loop will form here if there is no RPF.
Multicast will always take the same path as the unicast traffic from
client to the source would take, only in the opposite direction.

So, if your source was behind R1 and client behind R3, the traffic
will go S-->R1--{fa0/1)-->R2-->R3.

--
Marko Milivojevic - CCIE #18427
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On Thu, Nov 18, 2010 at 14:39, CCIE KID <eliteccie_at_gmail.com> wrote:
> It will take both the paths or else which path the multicast packet wll take
> to reach the source
> it cant take two paths
> which path it will take
>
>
> On Thu, Nov 18, 2010 at 8:05 PM, Marko Milivojevic <markom_at_ipexpert.com>wrote:
>
>> It would be reflected back to R1.
>>
>> --
>> Marko Milivojevic - CCIE #18427
>> Senior Technical Instructor - IPexpert
>>
>> FREE CCIE training: http://bit.ly/vLecture
>>
>> Mailto: markom_at_ipexpert.com
>> Telephone: +1.810.326.1444
>> Web: http://www.ipexpert.com/
>>
>> On Thu, Nov 18, 2010 at 14:33, CCIE KID <eliteccie_at_gmail.com> wrote:
>> > ok marko i understood ur point
>> > So in ur scenario in the full mesh topology the loop happens
>> > wat about this scenario
>> >
>> > B  B  B s0/1
>> > R1--------------------R2----------------------R3-
>> > B | B fa0/1 B  B  B  B  B  B  B  B  B  B  B |
>> > B | B  B  B  B  B  B  B  B  B  B  B  B |
>> > B | B  B  B  B  B  B  B  B  B  B  B  B |
>> > B |-------------------------|
>> >
>> >
>> > In this scenario if in IGP there are two routes which R2 can reach R1
>> > thorugh serial and fastetherent
>> > In this case wat would be the multicast path
>> > which path it would take if the packet comes from two paths
>> >
>> >
>> > On Thu, Nov 18, 2010 at 7:54 PM, Marko Milivojevic <markom_at_ipexpert.com>
>> > wrote:
>> >>
>> >> There is no RPF in that scenario and that's what would happen.
>> >> However, with RPF, when each of the routers receives copy of the
>> >> traffic from non-RPF interface, it will drop it.
>> >>
>> >> --
>> >> Marko Milivojevic - CCIE #18427
>> >> Senior Technical Instructor - IPexpert
>> >>
>> >> FREE CCIE training: http://bit.ly/vLecture
>> >>
>> >> Mailto: markom_at_ipexpert.com
>> >> Telephone: +1.810.326.1444
>> >> Web: http://www.ipexpert.com/
>> >>
>> >> On Thu, Nov 18, 2010 at 14:21, CCIE KID <eliteccie_at_gmail.com> wrote:
>> >> > No marko can u be little more clear
>> >> > wat is ur scenario deals wid RPF
>> >> >
>> >> >
>> >> > On Thu, Nov 18, 2010 at 7:47 PM, Marko Milivojevic <
>> markom_at_ipexpert.com>
>> >> > wrote:
>> >> >>
>> >> >> A---B
>> >> >> | X |
>> >> >> C---D
>> >> >>
>> >> >> So, we have full mesh of connections between A, B, C and D. Source is
>> >> >> attached to A. Source sends packet, A replicates it to B, C and D. C
>> >> >> replicates the packet to B and D (B and D receive their 2nd copy of
>> >> >> the same traffic). When B receives this traffic for C it replicates
>> it
>> >> >> to D (3rd copy), and back to A. A replicates it back to C, D... etc
>> >> >> etc etc. You get the idea?
>> >> >>
>> >> >> --
>> >> >> Marko Milivojevic - CCIE #18427
>> >> >> Senior Technical Instructor - IPexpert
>> >> >>
>> >> >> FREE CCIE training: http://bit.ly/vLecture
>> >> >>
>> >> >> Mailto: markom_at_ipexpert.com
>> >> >> Telephone: +1.810.326.1444
>> >> >> Web: http://www.ipexpert.com/
>> >> >>
>> >> >> On Thu, Nov 18, 2010 at 14:10, CCIE KID <eliteccie_at_gmail.com> wrote:
>> >> >> > Hey i know the RPF check happens every time when a multicast packet
>> >> >> > comes to
>> >> >> > router to check whether the same interface can be used to reach the
>> >> >> > source
>> >> >> > of the multicast feed.Why does this has been done?? To avoid
>> >> >> > loops!!!!
>> >> >> > *WHy
>> >> >> > RPF check is mandatory for a multicast packet*?
>> >> >> > If to avoid loops Can u give me a classic case of loop formation in
>> >> >> > multicasting when RPF is not present
>> >> >> >
>> >> >> >
>> >> >> > --
>> >> >> > With Warmest Regards,
>> >> >> >
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>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >
>> >> >
>> >> >
>> >> > --
>> >> > With Warmest Regards,
>> >> >
>> >> > CCIE KID
>> >> > IN PURSUIT OF CCIE
>> >> >
>> >
>> >
>> >
>> > --
>> > With Warmest Regards,
>> >
>> > CCIE KID
>> > IN PURSUIT OF CCIE
>> >
>>
>
>
>
> --
> With Warmest Regards,
>
> CCIE KID
> IN PURSUIT OF CCIE
>
>
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