Subject: sending of register stop message

From: "bhavesh pathak" <[email-masked]>
Date: Tue, 12 Oct 1999 21:30:07 PDT

Dear everybody,

In following configaration I am not able to understand when
RP will be able to send Register stop message to A?

>
>   --------  |
>   |Source|  |  1-----2 1-----2 1----2  1------2    |   ----------
>   |Host  |--+---| A |---| B |---|RP|----| C  |-----+---| Receiver|
>   --------  |   -----   -----   ----    ------     |   | Host2   |
>   ------->  |      ---------->  ------------->         -----------
>Data packet|      Register      forward
>             |                     decapsulated
>             |                     data packet
>
>
In the above situation A sends register message to RP for
(S,G)entry with RP bit set.
At this time A will have :
      (S,G) entry with iif = A1, oif = NULL(??) Registering bit set

Say RP has already existing (*,G) entry.
When RP receives Register,
- it will update iif to RP1 interface.
- it will send Join/Prune message towards A with (S,G) having RPT
  and WC bit clear.
- it will create (S,G) entry, copy oif from (*,G) entry with SPT bit
   clear.

When A receives Join/Prune :
- it will update oif to A2,
- will start sending data unencapsulated to RP and also encapsulted
   in RP message.

When RP receives unencapsulated data:
- it will find that (S,G) register message and unencapsulated data
   are coming on the same interface. So, it will not set SPT bit.
   This situation will persist for ever.

   So, it will not (NEVER) send register-stop message?

with regards,
bhavesh

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---

From: Pavlin Ivanov Radoslavov <[email-masked]>
Date: Tue, 12 Oct 1999 22:08:41 -0700

> - it will update iif to RP1 interface.

The (*,G) entry iif is never updated. The (*,G) entry in the RP will
always have iif=register_vif. Only the (S,G) entry iif can change.

Pavlin

---

From: [email-masked]
Date: Tue, 12 Oct 1999 22:02:28 -0700 (PDT)

>    This situation will persist for ever.

while the register may arrive on the same interface as the native
packet, the unicast register shouldn't be thought of as arriving on
the physical interface because it may not.

off-the-top-o-my-head i don't think there is a problem setting the spt 
on the RP since it's RPF(src) and RPF(RP) are indeed different :).
and hence the subsequent arrival of a register will invoke a regstop.

- rusty

---

From: helmy <[email-masked]>
Date: Tue, 12 Oct 1999 23:39:21 -0700 (PDT)

>    This situation will persist for ever.

No, the register decapsulation S,G entry will have an incoming interface
of the virtual interface (register vif), which indicates that the packet
was encapsulated in registers. When the native data arrives at the RP it
will match on the iif towards the Source, and not match on the register
vif.
	In short, there are ways to distinguish between decapsulated
registers and native data. For more info about the implementation details
you should probably look at the implementation document in
catarina.usc.edu/pim

Regards,
-A