Re: [pim] [PIM-SM] UpstreamJPState, SwitchToSptDesire and re-join

[G G <pimmulticast at gmail.com>]

Hi Huajun,

Please see inline with #GG#

On Mon, Aug 3, 2009 at 6:51 AM, huajun Lee <bestleehj at gmail.com> wrote:

 Hi,

    At the DR, when one source sent (S,G)data  to  the DR(interface E1)

         

         follow the 4.4.1 on page 37

               DownstreamJPState(S,G, E1) =Join

               immediate_olist(S,G) and inherited_olist(S,G)  (+) E1

         So the UpstreamJPState(S,G,E1) = Join, then Send Join(S,G), 

         Does it lack some description for not doing Send  ? So dose it at RP when a Join(*,G) arrived.         

      

         Need DR  creat (*,G)state before creat(S,G)?

#GG# Normally DR does not create (*,G) unless it is RP for G. It creates (S,G) state only.

  

   At the 27th page of the rfc4601

        SwitchToSptDesired(S,G) return true once a single packet has been received for the source and group

    is that mean: (S,G)data can be received on the interface I ( I != RPF(S) )

#GG# Yes, till Last-Hop router switches to SPT,  (S, G) data can arrive on interface I (I != RPF(S)). I is the interface towards the RP for G and it may or may not be same as interface towards source.

 

  At page 42   4.4.2

       packet_arrives_on_rp_tunnel(pkt){

             }

  

       where do the RP re-join  SPT?

#GG# I think receipt of first register packet will lead to creation of (S, G) on RP and if JoinDesired(S,G) is TRUE at RP, it will propogate (S, G) join upstream towards Source DR.
and when data packet arrives at RP, it updates the SPT bit as per Update_SPTbit(S,G,iif).

 

Regards,
GG