Subject: Sending Join/Prune Messages (Periodic)

From: "Mohit Talwar (Exchange)" <[email-masked]>
Date: Wed, 6 Oct 1999 15:32:46 -0700

Hi All,

A short question...

To give context, I quote from section 3.2.1...

---
   Periodic Join/Prune Messages:

   A router sends a periodic Join/Prune message to each distinct RPF
   neighbor associated with each (S,G), (*,G) and (*,*,RP) entry.
   Join/Prune messages are only sent if the RPF neighbor is a PIM
   neighbor.  A periodic Join/Prune message sent to a particular RPF
   neighbor is constructed as follows:

      1 Each router determines the RP for a (*,G) entry by using
        the hash function described. The RP address (with RPT and WC
        bits set) is included in the join list of a periodic Join/Prune
        message under the following conditions:

           1 The Join/Prune message is being sent to the RPF
             neighbor toward the RP for an active (*,G) or (*,*,RP)
             entry, and

           2 The outgoing interface list in the (*,G) or (*,*,RP)
             entry is non-NULL, or the router is the DR on the same
             interface as the RPF neighbor.
---

"...router is the DR on the same interface as the RPF neighbor."

Is this rule there to take care of the case when a DR finds that 
there are local receivers for a group on the RPF interface?  So 
the DR keeps the entry *active* till IGMP informs it that all local 
receivers have left the group.

Please let me know if I have misunderstood something.

Thanx,
Mohit.

---

From: [email-masked]
Date: Wed, 6 Oct 1999 15:45:19 -0700 (PDT)

> Please let me know if I have misunderstood something.

yes, this is correct.

- rusty