Subject: register supression and register stop

From: "Jyotheeswara Rao Kurma" <[email-masked]>
Date: Wed, 16 May 2001 17:30:47 +0500

Hi All :

  When RP won't send a Register Stop in response to a null register 
message from DR ? Or RP should send always register stop in response to 
a null register message ? Should RP check for anything when it receives 
a null register message, for an (S,G) for which it has some state ? or 
RP will blindly send a register stop in response to a null register 
message (if it has some (S,G) state )?

My Understanding is this:

  RP must send a register stop message in response to a null register 
message if it has (S,G) state. No need of of any other checks, like 
have any downstream receivers or not ? Because RP having/not having any 
downstream receivers, doesn't effect register stop, in any case RP has 
to send. Because 

1. if don't have any down stream receivers down the RP tree, he has to 
send register stop, before/after sending (S,G) prune. because not 
interested in receiving traffic to this group.

2. If it has any receivers , it has to send register stop, because 
encapsulation is an overhead.

If RP always sends register stop messgae, then why DR cann't assume 
that RP will send a register stop ? Is the probing mechanism that is 
described in the draft really affecting anything ? 

If RP's SPT bit of (S,G) is not set , then it shouldn't send a register 
stop message. Actually this cace shouldn't happen , because DR will 
send null registers, only after RST time after it receives register 
stop message . So who can meanwhile set the SPT bit to FALSE ?

what my question is :

what condtions will/will not let RP to send register stop messages in 
response to a null register message ? Moreover, I feel it will be good, 
if RP can send multiple(atleast not one) register stops in respose to a 
null register, to DR, because what happens if that single register stop 
is lost ? what happens if the null register messgae from DR didn't 
reach RP itself in the first palce ? again register encapsulation will 
start ?  As this encapsulation is an overhead I guess, we should 
consider into account the packet loss atleast to some extent ? 

Thanks in advance,
Jyotheesh

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