Subject: RE: [pim] doubt regard RP absence in the network

From: "[email-masked]" <[email-masked]>
Date: Tue, 17 Dec 2002 23:05:02 -0500 (EST)

Hi,
If you would see the macros pim_include(S, G) and pim_include(*, G). 
They have a procedure through which the oifs can have a state established. 
If iam correct it is through local_receiver_include, local_receiver_exclude mechanisms but with some other constraints also.
I will narrow my doubt now, will local_receive_include(S, G, I) for a  particular source be true if I receive a IGMPv2 Join?
Logically seeing it should be valid for all sources. And hence packet flow should be there even when the RP is unavailable.

The answer to question on what basis the (S, G) entry would be deleted ( or (S, G) state goes to NI state)  may be like this.
In the same way as local_receiver_include(S, G, I) is processed on (S, G) local_receiver_exclude(S, G, I) also should be processed for an IGMPv2 Leave.

Iam sorry for any mistakes in the answers above.

T & R
Rajesh Nataraja

 --- On Tue 12/17, Uma C  wrote:From: Uma C [mailto: [email-masked]]To: [email-masked]     Cc: [email-masked], [email-masked]: Tue, 17 Dec 2002 21:48:17 +0530Subject: RE: [pim] doubt regard RP absence in the network

Hello 
Jags
 
When 
there is no RP information -
1. 
(*,G) entry would surely get deleted. Outgoing interface in that (*,G) and 
(S,G) also gets deleted. So how are the packets still flowing 
?
2. If 
the (*,G) entry alone gets deleted because of the RP information not present and 
when the receiver leave the group, will the (S,G) entry get deleted ?. If yes 
how ? On what basis will this (S,G) entry get deleted.
I 
guess the entries at SPT built routers would get deleted only 
when source of the multicast packet stops sending 
packets.
 
I feel 
that, when the (*,G) entry gets deleted, (S,G) entry also would be deleted and 
there want be a case in which multicast packets will be flowing. Well I haven't 
thought about SSM case.

Pl 
correct me if I am in wrong in my understanding.
 
Thanks 
& Regards
C.Uma

  -----Original Message-----From: [email-masked] 
  [mailto:[email-masked]]On Behalf Of Rajamanickam 
  jaganbabuSent: Tuesday, December 17, 2002 8:38 PMTo: 
  [email-masked]; [email-masked]: Re: [pim] doubt 
  regard RP absence in the network
  Hi rajesh, 
    If the receiver and the source has the Source Path Tree established 
  (i.e if we have (S,G) entry in the Multicast forwarding table), then 
  irrespective of the RP information availability, the multicast packet will be 
  forwarded. 
    I hope the above information will help you, if i have understood 
  your question correctly. 
  Regards, 
  Jags 
   "[email-masked]"  
  wrote: 
  Hi,I 
    have the following doubt,If there is no RP in the network or all the 
    RPs expire in the network. Can there be packet forwarding activity in a 
    PIM-SM (only) domain. In clear my doubt is can the receivers switched over 
    to the packet forwarding via SPT still continue to receive the data packets 
    even if there is not RP information with him.thanks in 
    advancerajesh,

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---

From: "Uma C" <[email-masked]>
Date: Wed, 18 Dec 2002 13:55:47 +0530

Hello Rajesh

Pl find my comments inlined with the tag <UMA>.

In the case of SSM, I agree with what you had said. But in SM, I don't think
(S,G) entry would be present when (*,G) entries are getting deleted.

Regards
C. Uma

  -----Original Message-----
  From: [email-masked] [mailto:[email-masked]]On
Behalf Of [email-masked]
  Sent: Wednesday, December 18, 2002 9:35 AM
  To: [email-masked]
  Subject: RE: [pim] doubt regard RP absence in the network

  Hi, If you would see the macros pim_include(S, G) and pim_include(*, G).
They have a procedure through which the oifs can have a state established.
If iam correct it is through local_receiver_include, local_receiver_exclude
mechanisms but with some other constraints also. I will narrow my doubt now,
will local_receive_include(S, G, I) for a particular source be true if I
receive a IGMPv2 Join?
  [Uma C]  local_receive_include(S, G, I) for a particular source would be
true if IGMPv2 Join is received and successful in (*,G) entry creation, not
otherwise in the case of SM.
  ==========

  Logically seeing it should be valid for all sources. And hence packet flow
should be there even when the RP is unavailable. The answer to question on
what basis the (S, G) entry would be deleted ( or (S, G) state goes to NI
state) may be like this.
  In the same way as local_receiver_include(S, G, I) is processed on (S, G)
local_receiver_exclude(S, G, I) also should be processed for an IGMPv2
Leave.
  [Uma C] The interface "I" connected to the receiver gets added up to (S,G)
only through (*,G). So when the (*.G) entry is deleted, the Interface would
be deleted from (S,G) also.
  If there is no (*,G) entry nor RP information, and as you had said when
(S,G,I) can process the IGMP Leave, can (S,G) add the interface "I" when an
IGMPv2 Join comes.

  I think in the case of SSM what you had mentioned is applicable. But in
SM, without RP, packet flow should not happen. Anyway when the RP
information is got, the multicast tree is rebuilt.

  Logically seeing, this can never happen in real time until someone is
playing around. If thats the case, packets loss should be fine. Pl correct
me if I am wrong.
  ============

  Iam sorry for any mistakes in the answers above.
  [Uma C] "Making mistake is human being's privilege". I also proved this
many times :-)

  T & R Rajesh Nataraja

  --- On Tue 12/17, Uma C < [email-masked] > wrote:
  From: Uma C [mailto: [email-masked]]
  To: [email-masked]
  Cc: [email-masked], [email-masked]
  Date: Tue, 17 Dec 2002 21:48:17 +0530
  Subject: RE: [pim] doubt regard RP absence in the network

  Hello Jags

  When there is no RP information -
  1. (*,G) entry would surely get deleted. Outgoing interface in that (*,G)
and (S,G) also gets deleted. So how are the packets still flowing ?
  2. If the (*,G) entry alone gets deleted because of the RP information not
present and when the receiver leave the group, will the (S,G) entry get
deleted ?. If yes how ? On what basis will this (S,G) entry get deleted.
  I guess the entries at SPT built routers would get deleted only when
source of the multicast packet stops sending packets.

  I feel that, when the (*,G) entry gets deleted, (S,G) entry also would be
deleted and there want be a case in which multicast packets will be flowing.
Well I haven't thought about SSM case.

  Pl correct me if I am in wrong in my understanding.

  Thanks & Regards
  C.Uma

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