Re: Multicast Data

bit unclear about last point .... please clarify further if you can ....
__
btharindu.blogspot.com

On Fri, Apr 9, 2010 at 4:01 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar> wrote:

> Adding to that that has been said:
> -yes, you can loose first, second, third... any, cause Mcast runs
> over UDP and there are no L4 delivery warranties. Actually, there
> are very few L7 protocols that have assured delivery over mcast.
>
> -registration does not stop when S (source router) receives join from
> RP, so there can be many packets going unicast to RP.
> RP tells S to stop registration after it receives direct mcast from S,
> so no packets lost in between.
>
> -sending can start before receivers have joined the RP, in which case
> the RP will stop registration w/o joining the source. Then you it will
> start a slow "flapping", trying to register every 3 mins, and being
> call to silence untill a receiver shows up.
>
> I guess you can loose up to 3 minutes of the show if nobody was
> listening and you are late to the start :)
>
> -Carlos
>
>
>
> Kambiz Agahian @ 9/04/2010 3:44 -0300 dixit:
> > Hi Tharin,
> >
> > Good point!
> > First off, I'm hoping that my interpretation of your question is correct
> > anyway correct me if your question if not exactly this but actually the
> > problem is that almost all resources (including most pages on cisco.comand
> > juniper.com as well as the RFC!) focus on the "second" action taken by
> the RP
> > after receiving the registration request! and the first (but the less
> > important action) is somehow ignored (or underestimated)....
> >
> > Here is the process (briefly):
> >
> > Your Windows 2003 Media server starts sending the Multicast packets of
> (analog
> > term : broadcasting) "The Family guy". The first Mcast packets hit their
> > gateway and the DR of that segment tries to get a hold of the RP to kick
> off
> > the registration process. You know the encapsulation process (the actual
> mcast
> > content inside a unicast packet - right?) so the RP gets the first
> capsule and
> > "extracts" the multicast content. At this stage the RP has to take two
> > actions:
> >
> > 1- It sends the extracted Multicast packet down the tree based on the
> (*,G).
> > Where did you get that from? my Visa client had talked to his DR and his
> DR to
> > his upstream then to his upstream...all the way up to the RP to indicate
> his
> > interest. So before getting the first packet (the capsule) as you
> mentioned
> > the RP does know that I'm waiting to watch Quagmire (there is a receiver
> down
> > there). In fact the (*,G) is on the RP waiting for the source to come up.
> >
> > 2- The RP then tries to join the group and now everyone knows what's
> gonna
> > happen afterwards...I save some key strokes.
> >
> > Well, as you see (the first action), even the first packet (probably the
> first
> > frame of the Fox ad!) is delivered by the RP to (*,G) to ensure nothing's
> > going to be missed.
> >
> > HTH
> >
> >
> >
> >
> > Kambiz Agahian
> > CCIE (R&S)
> > CCSI, WAASSE, RSSSE
> > Technical Instructor
> > CCBOOTCAMP - Cisco Learning Solutions Partner (CLSP)
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> >
> >
> > -----Original Message-----
> > From: nobody_at_groupstudy.com on behalf of Tharindu Rukshan Bamunuarachchi
> > Sent: Thu 4/8/2010 10:04 PM
> > To: ccielab_at_groupstudy.com
> > Subject: Multicast Data
> >
> > hi Experts,
> >
> > In sparse-mode, AFAIK first packet is forwarded to RP as unicast. (In
> > Register Unicast process).
> >
> > Is there any possibility to lose first packet without being delivered to
> > destination. (assuming destination is already subcribed to multicast
> tree)?
> >
> >
> > __
> > btharindu.blogspot.com
> >
> >
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> >
> >
>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina

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Received on Fri Apr 09 2010 - 17:01:36 ART