Re: Multicast Data

Dear,
if you remember, the question was about loosing the fisrt packet or so.
How can be loosing the first minutes off the path ?
Anyhow, I understand the matter is confising at times. But I always
think that confusion comes fisrt and wisdom comes after!

As for the waiting times, those are actually related to the numbers
you see when you do a show ip mroute.

Feel free to ask if you need further assistance.
-Carlos

Kambiz Agahian @ 11/04/2010 23:46 -0300 dixit:
> Carlos/Tharin,
>
> Now it's getting a bit off the path...I reckon there is huge confusion here.
>
> Tharin,
> Stop learning and just hang on a sec mate.
>
> Carlos,
> Where do you get those timers from? 3-min waiting period etc. Please
> note that he is talking about a PIM-SM network with a (S,G) entry
> created on the closest router to your Multicast source...do you know
> what's going to happen to this entry if you're the first receiver and
> you're late (as you say...)?
>
> If you let me know what you mean by missing packets and waiting times
> I'll surely shed some light...
>
>
>
>
>
> --------------------------
> Kambiz Agahian
> CCIE (R&S)
> CCSI, WAASSE, RSSSE
> Technical Instructor
> CCBOOTCAMP - Cisco Learning Solutions Partner (CLSP)
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>
>
> -----Original Message-----
> From: Tharindu Rukshan Bamunuarachchi [mailto:btharindu_at_gmail.com]
> Sent: Sun 4/11/2010 6:51 PM
> To: Carlos G Mendioroz
> Cc: Kambiz Agahian; ccielab_at_groupstudy.com
> Subject: Re: Multicast Data
>
> hm ...
>
> okay, so if i join the tree after starting the show (e.g. after 20 seconds)
> ... as RP does not keep potential sources ... i wont receive multicast data
> until 3 minutes timeout.
>
> is it possible to minimize 3 minutes ...
> __
> tharindu rukshan
> blog.tharindu.info
>
>
>
> On Fri, Apr 9, 2010 at 5:28 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar> wrote:
>
>> I'd prefer you making the effort and ask what is that is unclear.
>> But there are lots of cases in multicast where things get fixed
>> after some timeout, and it happens to be 3 minutes by default.
>> The RP keeps no info on potential sources if there are no receivers
>> for a group, and will kill the registration attempt w/o joining in
>> that case.
>>
>> Makes sense ?
>>
>> Tharindu Rukshan Bamunuarachchi @ 9/04/2010 8:31 -0300 dixit:
>> > 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)
>> >>> Email: kagahian_at_ccbootcamp.com
>> >>> Toll Free: 877-654-2243
>> >>> International: +1-702-968-5100
>> >>> Skype: skype:ccbootcamp?call
>> >>> FAX: +1-702-446-8012
>> >>> YES! We take Cisco Learning Credits!
>> >>> Training And Remote Racks: http://www.ccbootcamp.com
>> >>> OEQ Voice Waiver: http://www.ccbootcamp.com/noeqvoice.html
>> >>> OEQ R&S Waiver: http://www.ccbootcamp.com/noeqrs.html
>> >>> OEQ Commercial: http://www.ccbootcamp.com/noeq.mpg
>> >>>
>> >>>
>> >>> -----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
>> >>>
>> >>>
>> >>> Blogs and organic groups at http://www.ccie.net
>> >>>
>> >>>
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> _______________________________________________________________________
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>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >> --
>> >> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>> >
>> >
>> > Blogs and organic groups at http://www.ccie.net
>> >
>> > _______________________________________________________________________
>> > Subscription information may be found at:
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>> >
>> >
>> >
>> >
>> >
>> >
>> >
>>
>> --
>> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina
>>
>

-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
Blogs and organic groups at http://www.ccie.net