Re: IGMP Router Group Membership state

Thanks a lot Bharath.

I have tried with an example to understand this entry in the table 6.4.2


Router State    Report Rec’d     New Router State     Action
------------    ------------     ----------------     -------

INCLUDE (A)        TO_EX (B)      EXCLUDE (A*B,B-A)    (B-A)=0

                                                      Delete (A-B)

                                                     Send Q(G,A*B)

                                                  Group Timer=GMI



Lets say that the router initially is in INCLUDE state for a group, with the
following sources.

10.10.10.10,  10.10.10.11, 10.10.10.12

Now it received a report "TO EXCLUDE 10.10.10.10"

So, as per the above entry, the router new state should be :

EXCLUDE (A*B,B-A).

So, the router new state is EXCLUDE, with the include list as A*B,

i.e 10.10.10.10, as this is the only one common in A and B.

And the exclude list is B-A, which is nothing but zero in this case.

So, the final state can be said as EXCLUDE nothing for the group (Exclude
list) with 10.10.10.10 requested for forwarding (Include List).

Please let me know whether the understanding is right.



Thanks,

RajaSekhar








On Mon, Jan 18, 2010 at 6:27 PM, Bharat Joshi <[email protected]>wrote:

> RajaSekhar,
>
>         I am not sure what you exactly mean by 'please explain on what is
> "EXCLUDE (A*B,B-A)". I understand that this does not look straight forward
> but if you do the calculation with a list of source and group address, you
> will see that this is just perfect. Same is true with the other rule. Please
> use a specific group-address and source address to check them out.
>
>        The sources in the include list are those which has been explicitly
> asked to be allowed. This is maintained so that a router can move from
> Exclude to Include mode as and when group-timer fires. Source in exclude
> list are simply not forwarded and is explicitly asked to be excluded by
> someone on LAN.
>
> Thanks,
> Bharat
> ________________________________________
> From: rajasekar bonthala [[email protected]]
> Sent: Monday, January 18, 2010 6:01 PM
> To: Bharat Joshi
> Cc: [email protected]; [email protected]
> Subject: Re: [magma] IGMP Router Group Membership state
>
> Bharat,
>
> Thanks a lot for the reply.
> In the first rule can you please explain on what is "EXCLUDE (A*B,B-A)" and
> what is the meaning of action of the router i.e :-
>
>  (B-A)=0
>  Delete (A-B)
>  Send Q(G,A*B)
>  Group Timer=GMI
>
> In the seconds rule can you explain me the meaning of "EXCLUDE (X+A,Y-A)"
> and "(A)=GMI
> "
>
> You said that in the exclude mode, it maintains two lists, one is the
> exclude list and the other is the include list. Is it that Exclude list to
> inform about the blocked sources and Include list to inform the sources from
> which the multicast packets are allowed. Am i correct.
>
> Thanks,
> RajaSekhar
>
> On Mon, Jan 18, 2010 at 5:31 PM, Bharat Joshi <[email protected]
> <mailto:[email protected]>> wrote:
> Raja,
>
>       When the To_Ex(A) is received, router will change its mode to
> EXCLUDE. In exclude mode, it maintains two list. Following rule will apply:
>
>
>       INCLUDE (A)    TO_EX (B)    EXCLUDE (A*B,B-A)       (B-A)=0
>
>       Delete (A-B)
>
>       Send Q(G,A*B)
>
>       Group Timer=GMI
>
>        Now when router generates group-source specific query and it gets a
> response with IS_INC(A). Following rule will apply:
>
>        EXCLUDE (X,Y)  IS_IN (A)     EXCLUDE (X+A,Y-A)        (A)=GMI
>
>       The state as per this will be EXCLUDE mode with source 'A' in Include
> list and exclude list will now be empty.
>
>       Now if the response does not come, state will be EXCLUDE (A*B,B-A)
> which is an empty include list and source 'A' in exclude list.
>
> Thanks,
> Bharat
> ________________________________________
> From: [email protected]<mailto:[email protected]> [
> [email protected]<mailto:[email protected]>] On Behalf Of
> rajasekar bonthala [[email protected]<mailto:
> [email protected]>]
> Sent: Monday, January 18, 2010 4:30 PM
> To: [email protected]<mailto:[email protected]>; [email protected]<mailto:
> [email protected]>
>  Subject: [magma] IGMP Router Group Membership state
>
> Hi All,
>
> Section 6.4.2 of RFC 3376 talks about on how should IGMP routers respond on
> receiving Filter Mode Change and Source List Change records.
>
> I do not get about what should be the action of the IGMP router in the
> following scenario.
>
> Router is in "INCLUDE A"  state. It receives a report "TO EXCLUDE A". Here,
> IGMP Router sends a Group and Source specific query for the source A group
> B.
>
> Let us say that IGMP Router receives a response "IS INCLUDE A".
>
> What should be the state of the IGMP Router before and after receiving
> response?
> What should be the state of the IGMP Router if it doesn't receive any
> response before the last member query time expires?
>
> In my IGMP Router I could see the state as below :
>
> BEFORE RESPONSE :
>
> atca-f120#show ip igmp groups detail
> Interface:      ge45
> Group:          224.0.6.130
> Uptime:         00:00:20
> Group mode:     Exclude (Expires: 00:06:22)
> Last reporter:  192.168.1.8
> Group source list: (R - Remote, M - SSM Mapping, S - Static)
> Include Source List :
>  Source Address  Uptime    v3 Exp    Fwd  Flags
>  10.10.10.10     00:00:20  00:00:27  Yes  R
>
>
>
>
> NO RESPONSE :
>
> atca-f120#show ip igmp groups detail
> Interface:      ge45
> Group:          224.0.6.130
> Uptime:         00:00:49
> Group mode:     Exclude (Expires: 00:05:53)
> Last reporter:  192.168.1.8
> Group source list: (R - Remote, M - SSM Mapping, S - Static)
> Exclude Source List :
>  Source Address  Uptime    v3 Exp    Fwd  Flags
>  10.10.10.10     00:00:49  stopped   No   R
>
>
> But could not interpret the above outputs. Can anyone help me.
>
> Thanks,
> RajaSekhar
>
>
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