[pim] Re: BSM: is it bidir or ASM

[John Zwiebel <jzwiebel at cisco.com>]

FWIW:

This can be "fixed" at the BSR.  For a group range that has more
than one RP being advertised, if any RP is a bidir RP, the bidir
flag MUST be set for the multicast group range in the BSM.

(or you could go the other way and make it ASM (PIM-SM) if you
really wish.  point being, we need one or the other.)

Also, if the 'offending' RP is deconfigured (ie the group range
is suppose to be ASM but the RP is misconfigured to be bidir,
then the C-RP message removing that RP will immediately remove
it from the RP cache and should also trigger a BSM with the correct
bidir flag -- off -- so the network gets "fixed" right away and there
shouldn't be a need to timeout any RP on the clients)


On May 8, 2006, at 3:29 PM, John Zwiebel wrote:

> On May 8, 2006, at 12:59 PM, Stig Venaas wrote:
>
> > Based on the feedback
>
>
> Here's a new bug for you Stig.
>
> What if you have two C-RPs both advertising the same group range, but
> one is bidir and one is ASM?
>
> Since the RP address is a subset of the encoded group range, you have
> to pick one or the other.
>
> And the BSR has to recognize this and either reject the C-RP from the
> bidir or asm RP or make the great leap of faith and choose whether the
> group is bidir or ASM for itself.
>
> (Oh, of course, one could weasel out of it and say it was a  
> misconfiguration)
>
> 3.6 talks about whether or not a given router can support bidir and  
> asm
>
> but there are no other references that describe which one has  
> priority.
>
> Can I suggest bidir should always win.  :-)

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