Subject: Re: PIM-Sm: Assert message for (S,G) when (S,G) state is "Noinfo"

From: Bill Fenner <[email-masked]>
Date: Tue, 15 May 2001 19:00:24 -0700

>So, in the implementation, we need to maintain a (S,G)
>entry if we lost the assert for (S,G), even if "Local
>membership(S,G) state" and "PIM(S,G) Join/Prune state"
>are "non info". clarify me if i am wrong.

Yes, you need to store the (S,G) Assert Winner state somewhere.

  Bill

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From: muthireddy ramakoteswararao <[email-masked]>
Date: Thu, 17 May 2001 10:22:35 -0700 (PDT)

Hi, 
 I have two doubts in the section 4.5.5 of new PIM-SM
draft.

(1)It has been mentioned that, when the (S,G,I) Assert
state is "Noinfo", AssertWinner( S,G,I) is NULL.
 If so, AssertWinner(S,G,I) !=me is TRUE in this state
and  lost_assert(S,G,rpt,I) becomes true in the "else"
part of this macro. This makes this interface to be
removed from the "inherited_olist(S,G,Rpt)". 
  Why should we remove this interface even when no
other router is willing to forward on this LAN.

(2) There are default values defined
for"AssertWinner(S,G,I)" and 
"AssertWinnerMetric(S,G,I)". But, there are no defined
defaults for "AssertWinner(*,G,I)", which has been
used in the "lost_assert(*,G,I)" macro.

Thanks,
-Ramko.

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From: "Srikanth Kumar" <[email-masked]>
Date: Tue, 22 May 2001 07:42:16 -0400

Hi,
PIM is supposed to query the  MRIB to determine its RPF information.
Question 1:
what are the components of the MRIB, and how is the RPF computed?
There are two schools of thought here:
1. MRIB should only contain MBGP routes marked multicast only; unicast +
multicast; static (multicast) routes.
Confusion: Unless unicast routes within AS are a part of MRIB, RPF
information for sources within AS will not exist.

2. The second method of computing RPF is via a decision process where
admin weights are given to unicast routes, MBGP routes, and static
routes, and the route with the best admin weight is chosen.
Confusion: This seems to defeat the purpose of having MRIBs- Doesn't an
MRIB exist so that the multicast and unicast topologies could be
non-congruent?

Thanks in advance.
Srikanth Kumar/

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From: "Hal Sandick" <[email-masked]>
Date: Tue, 22 May 2001 10:22:33 -0400

Srikanth,

First, the mrib is a logical construct. How it is realized is an
implementation decision.  You might have one monolithic unicast and
multicast routing table with entries marked to indicate their respective
multicast capabilities. I've worked on one like this.  You could have a mrib
that contains multicast only routes and a rib that contains unicast and
unicast/multicast routes.  The mrib would be searched first.  If there was
no hit in the mrib,  the unicast rib would be searched (doing the
appropriate checks of course).  I've worked on one of these too.  There are
other variations on these themes.

So, without appropriate checks (e.g. multicast capability)  "2)" is
definitely wrong.

Hope this helps.

Regards,

Hal