RE: (*,G) entries upstream of the RP in sparse mode

Hi,

  Exactly and if i remember correctly this is outlined in PIM-SM RFC.

Regards,
Cristian.
>
>
>
>---- Original Message ----
>From: bob_at_bobsinclair.net
>To: o.neghina_at_gmail.com, ccielab_at_groupstudy.com,
>comserv_at_groupstudy.com
>Subject: RE: (*,G) entries upstream of the RP in sparse mode
>Date: Sat, 21 Aug 2010 11:45:09 -0400
>
>>Hello Ovidiu,
>>
>>In sparse mode in Cisco IOS the (*,G) entry is created when:
>>
>> 1. a router receives an IGMP membership report from a client or a
>>PIM join message from a downstream router
>> 2. a multicast stream is detected and (S,G) state must be created
>>
>>The exception is source specific multicast, in which no (*,G) state
>is
>>maintained.
>>
>>As you suggest, the (*,G) shared tree is not used to distribute
>traffic
>>between the source and the RP and is unnecessary.
>>
>>The (*,G) entry is not used to distribute traffic in dense mode; it
>is
>>simply a parent data structure for the (S,G), so I do not believe it
>is
>>related to dense mode fallback.
>>
>>HTH,
>>
>>Bob Sinclair CCIE 10427 CCSI 30427
>>CIERS2 Online Instructor
>>www.tinyurl.com/ciers2online
>>
>>> -----Original Message-----
>>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
>Behalf Of
>>> Ovidiu Neghina
>>> Sent: Saturday, August 21, 2010 6:46 AM
>>> To: Cisco certification; Cisco certification
>>> Subject: (*,G) entries upstream of the RP in sparse mode
>>>
>>> Hi
>>> I have a short question.
>>> we have a sparse mode scenario with static RP - R3 with this
>topology
>>> from antonio soares lab:
>>> http://ccie18473.net/dynamips/dynamips.htm#pim-sm
>>> Topology is : Source-R1-R2-R3-R4-R5-Receiver
>>> Why do we have on R1, and R2 (*,G ) entries when sending traffic
>from
>>> the source ? I know that is normal to have it dowstream of the RP
>but
>>> i don't understand whey we have it upstream of the RP ? Is it for
>>> dense mode fallback ?
>>>
>>> R1#sh ip mroute 224.1.1.1
>>> (*, 224.1.1.1), 00:00:26/stopped, RP 3.3.3.3, flags: SPF
>>> Incoming interface: Serial1/1, RPF nbr 12.12.12.2
>>> Outgoing interface list: Null
>>> (10.10.10.1, 224.1.1.1), 00:00:26/00:03:28, flags: FT
>>> Incoming interface: FastEthernet0/0, RPF nbr 0.0.0.0
>>> Outgoing interface list:
>>> Serial1/1, Forward/Sparse, 00:00:26/00:03:04
>>>
>>> br
>>> Ovidiu
>>>
>>>
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Received on Sat Aug 21 2010 - 19:24:51 ART