Subject: Re: SPT bit in (S,G) entry

From: Isidor Kouvelas <[email-masked]>
Date: Wed, 11 Apr 2001 09:27:04 -0700

"Jyotheeswara Rao Kurma" writes:
>Case 3 : At RP.
>
>I guess there is no damage to the functionality, even if we set SPT bit 
>after receiving the first Register packet, (i.e while creating the (S,G)
>entry itself.) Because RP must join the SP tree, if it has some 
>receives down the RP tree. 

This is not the case. The SPT bit must be set when native data packets
arrive. Setting the SPT bit is what triggers the RP to start sending
Register-Stop messages in response to registers.

thanks
I

---

From: "Jyotheeswara Rao Kurma" <[email-masked]>
Date: Thu, 12 Apr 2001 09:11:30 +0500

> Register-Stop messages in response to registers.

What I thought is , any way RP (because it has some receivers down the 
RP tree) is interested in forming SPT tree with the DR, so let RP send 
both register stop( which eliminates encapsulation and decapsulation 
overhead), and also (S,G) join towards DR . 

But (S,G) join is a hop-by-hop process, resulting in (S,G) states in 
all intermediate routers, whereas Register stop is a unicast to DR.

So, after receiving Register-Stop till the (S,G) joins comes to DR,
it will discard packets thus resulting in loss of some data.  

So, RP should not send Register-Stop till the SP Tree is formed.(i.e 
SPT bit is set.) if it has some receivers doen the Tree. And SPT bit  
is set only when native multicast packets starts arriving. Am I 
correct ?

register -stop should only be sent 

1. After  SP tree is formed with DR.
2. RP has no down stream receivers.

Thanks Kouvelas,
Jyotheesh