Subject: Adding back pruned oifs

From: "Vaishali Pandya" <[email-masked]>
Date: Wed, 20 Sep 2000 11:12:54 -0700

Hi,
 Can somebody explains how the following configuration will work?

                                    Snd-----R1-------R2--------R3-------Rcvr
                                                                     (RP)
If the Snd is sending data and the Rcvr goes away then each router will have
following entries:

R1- S,G with null oif

R3- No, S,G Entry

Now, if the Rcvr joins again, how does R1 recalculate oifs and start
forwarding data?

-Vaishali

---

From: Bill Fenner <[email-masked]>
Date: Wed, 20 Sep 2000 12:49:37 -0700

>                                    Snd-----R1-------R2--------R3-------Rcvr

I'm not sure where the RP is meant to be; I'll guess R2.  Make sure
you use a constant-width font when you draw ASCII art, or it will look
different on different displays.

>Now, if the Rcvr joins again, how does R1 recalculate oifs and start

The RP will have remembered that it sent a (S,G) prune for the sender,
and when it gets the (*,G) Join from R3 because the receiver joined
again, it will send an (S,G) Join towards R1.

If the RP weren't in the middle of the path, data would flow down the
(*,G) tree until R3 decided to switch to the shortest path tree; since
the RP is in the middle these paths are the same.

  Bill

---

From: Bill Fenner <[email-masked]>
Date: Wed, 20 Sep 2000 13:24:42 -0700

>RP is at R3. So, How join towards S will go out?  

>R3- No, S,G Entry   

The RP must remember any sources that it sent a prune towards, if it
doesn't want to cause large join latency.  If it fails to keep this state,
it will have to wait for R1 to send it a Null-Register which will remind
it of the presence of the source, which could be as long as 60 seconds.

  Bill

---

From: "Vaishali Pandya" <[email-masked]>
Date: Wed, 20 Sep 2000 13:16:20 -0700

-----Original Message-----
From: Bill Fenner [mailto:[email-masked]]
Sent: Wednesday, September 20, 2000 3:50 PM
To: Pandya, Vaishali [SC7:370:EXCH]
Cc: [email-masked]
Subject: Re: Adding back pruned oifs

  Bill

---

From: Bill Fenner <[email-masked]>
Date: Wed, 20 Sep 2000 16:30:55 -0700

>How long does the RP need to maintatin (Sp,G) information if no receivers
>join the RP?  

Until the source stops sending.  (The RP need not keep state at all if
unpredictably increased join latency is acceptable.)

>If RP fails to keep the (Sp,G) state, is RP supposed to create (S,G) state
>with the Null-Register msg?   

Whether the RP joins to the source immediately or just decapsulates
and forwards Register messages is a policy decision.  If the policy
says to join immediately, then yes, the Null-Register would create
(S,G) state.

  Bill

---

From: "Sri Kopalle" <[email-masked]>
Date: Wed, 20 Sep 2000 16:24:21 -0700

>>The RP must remember any sources that it sent a prune towards, if it
doesn't want to cause large join latency. 

>>If it fails to keep this state,

  Bill