Re: magma Digest, Vol 46, Issue 2

Hi Mark, thanks for the reply. But I still have a doubt, LMQC configured
on the Querier may not be same as QRV, Section 8.9 says that the default
value of LMQC is Robustness Variable, but if it is configured to some
non-default value then QRV and LMQC will be different. In that case
there will be a mismatch of LMQT between Querier and Non-Querier, isn't
it??

Thanks
Suvendu.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Mark Fine
Sent: Tuesday, May 27, 2008 10:56 PM
To: Rajib Karmakar
Cc: [email protected]
Subject: Re: [magma] magma Digest, Vol 46, Issue 2

Section 6.6.1 "Timer Updates" explains that timers are updated on the  
sending or receiving of a query. A non-querier does not update timers  
when it receives reports -- it updates timers when it receives group- 
specific or group-and-source-specific queries from the elected querier.

As alluded to, routers in a network (querier and non-queriers) can be  
configured with different LMQI and LMQC values, so having non-querier  
routers update timers when they receive reports will lead to  
inconsistent aging out of membership records. Rather, non-queriers  
should only update timers on reception of group-specific or group-and- 
source-specific queries -- LMQI and LMQC can be calculated from the  
queries Max Resp Code and QRV fields, respectively.

On May 26, 2008, at 10:13 PM, Rajib Karmakar wrote:

> There will be no variation in the behaboiur between a querier and  
> non-querier except that queiriers will send quieries. Both will  
> follow the IGMP router functionality.Whenever a router (Querier or  
> non-querier) recieves a report it should process it and do whatever  
> is required (setting the group-source state and updating timers) and  
> if it is a queroer then it will also send the queries whenever  
> required. So, in this scenario the non-querier will also update the  
> timer at the same time when the querier does. Also the value of LMQT  
> will be same as the value of LMQI is known to the non-quirer at the  
> time of Querier Election and all the systems in a IGMP network  
> should be configured with same Robustness value which is in terms  
> been used as LMQC.
>
> On Tue, May 27, 2008 at 12:30 AM, <[email protected]> wrote:
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> Today's Topics:
>
>   1. Re: Non-Querier behaviour on receiving grp specific or
>      grp-and-src specific queries (ravikumar vj)
>   2. Re: Non-Querier behaviour on receiving grp specific
>      orgrp-and-src specific queries (Suvendu Mozumdar)
>   3. Re: Non-Querier behaviour on receiving grp specific
>      orgrp-and-src specific queries (Bharat Joshi)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 25 May 2008 21:27:46 -0700 (PDT)
> From: ravikumar vj <[email protected]>
> Subject: Re: [magma] Non-Querier behaviour on receiving grp specific
>        or      grp-and-src specific queries
> To: [email protected]
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi Bharat,
>            Why the non-querier have to wait till it receives a grp  
> specific or grp-and-src specific query? Why cant the non-querier  
> update the timers on receiving the reports it-self.
>            As per given in the example when the Querier receives the  
> BLOCK (S1), he updates the timer of S1 to LMQT and sends a Grp-and- 
> src specific query for S1. Why can the non-qurier update the timer  
> of S1 to LMQT as well (and DONT send query), when he receives the  
> report. Why the non-querier have to wait till he receives the Grp- 
> and-src specific query to update his timers?
>
>  Thanks and Regards
>  Ravikumar V J
>
> Message: 1
> Date: Fri, 23 May 2008 01:25:57 -0700
> From: "Suvendu Mozumdar"
> Subject: [magma] Non-Querier behaviour on receiving grp specific or
> grp-and-src specific queries
> To:
> Message-ID:
> <4C3C777A1128A74BA27FECF4E421BCBE0261077F@IXCA-EXCHANGE.ixiacom.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi,
>
> I have an issue for which the RFC 3376 does not suggest anything.
> Lets say in a Lan there are two igmpv3 routers and one igmpv3 host
> present. Lets say Q1 is querier and Q2 is non-querier. Now Host1 sends
> include s1 for grp G1. Both Q1 and Q2 will have an entry in their
> respective database. Now Host1 sends a report block s1 for grp G1.  
> Q1 on
> receipt of this block report will start LMQT timer, set the source  
> timer
> of s1 to LMQT and start sending group and source specific queries for
> G1/s1. After LMQT expires Q1 will delete the entry of G1/s1 from its
> database. Now what will be the non-querier's behaviour. Will it also
> start LMQT, in that case Querier's LMQT and non-querier's LMQT  
> (which is
> LMQC*LMQI) may differ based on different LMQC values. Non-querier  
> comes
> to know about the querier's LMQI from the Max Response Code in the
> specific query pkt but what about querier's LMQC, non-querier has no  
> way
> to know about the querier's LMQI.
>
>
>
> Can anyone throw some light on this?
>
>
>
> Thanks
>
> Suvendu.
>
>
>
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> ------------------------------
>
> Message: 2
> Date: Fri, 23 May 2008 14:07:00 +0530
> From: Bharat Joshi
> Subject: Re: [magma] Non-Querier behaviour on receiving grp specific
> or grp-and-src specific queries
> To: Suvendu Mozumdar
> Cc: "[email protected]"
> Message-ID: <1211531820.22712.19.camel@magadha>
> Content-Type: text/plain; charset=
>
> Suvendu,
>
> >
> > I have an issue for which the RFC 3376 does not suggest anything.
> > Lets say in a Lan there are two igmpv3 routers and one igmpv3 host
> > present. Lets say Q1 is querier and Q2 is non-querier. Now Host1  
> sends
> > include s1 for grp G1. Both Q1 and Q2 will have an entry in their
> > respective database. Now Host1 sends a report block s1 for grp G1.  
> Q1
> > on receipt of this block report will start LMQT timer, set the  
> source
> > timer of s1 to LMQT and start sending group and source specific
> > queries for G1/s1. After LMQT expires Q1 will delete the entry of
> > G1/s1 from its database. Now what will be the non-querier's  
> behaviour.
> > Will it also start LMQT,
>
> Please look at section 6.6.1. When a non-querier receives a query, it
> reduces its corresponding timer to LMQT which can be derived from
> max-response code.
>
> > in that case Querier's LMQT and non-querier's LMQT (which is
> > LMQC*LMQI) may differ based on different LMQC values. Non-querier
> > comes to know about the querier's LMQI from the Max Response Code in
> > the specific query pkt but what about querier's LMQC, non-querier  
> has
> > no way to know about the querier's LMQI.
>
> Non-querier does not need to know LMQC as it is not required. LMQC is
> required for a querier to generate number of queries.
>
> Also most of the times, it is expected that all routers are configured
> with same values but things should still work if they are not.
>
> Hope this helps.
>
> Thanks,
> Bharat
>
>
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> End of magma Digest, Vol 46, Issue 1
> ************************************
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> ------------------------------
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> Message: 2
> Date: Sun, 25 May 2008 22:17:46 -0700
> From: "Suvendu Mozumdar" <[email protected]>
> Subject: Re: [magma] Non-Querier behaviour on receiving grp specific
>        orgrp-and-src specific queries
> To: "Bharat Joshi" <[email protected]>
> Cc: [email protected]
> Message-ID:
>
<4C3C777A1128A74BA27FECF4E421BCBE02693CEF@IXCA-EXCHANGE.ixiacom.com 
> >
> Content-Type: text/plain;       charset="us-ascii"
>
> Hi Bharat, please see inline :
>
> -----Original Message-----
> From: Bharat Joshi [mailto:[email protected]]
> Sent: Friday, May 23, 2008 2:07 PM
> To: Suvendu Mozumdar
> Cc: [email protected]
> Subject: Re: [magma] Non-Querier behaviour on receiving grp specific
> orgrp-and-src specific queries
>
> Suvendu,
>
> >
> >      I have an issue for which the RFC 3376 does not suggest  
> anything.
> > Lets say in a Lan there are two igmpv3 routers and one igmpv3 host
> > present. Lets say Q1 is querier and Q2 is non-querier. Now Host1  
> sends
> > include s1 for grp G1. Both Q1 and Q2 will have an entry in their
> > respective database. Now Host1 sends a report block s1 for grp G1.  
> Q1
> > on receipt of this block report will start LMQT timer, set the  
> source
> > timer of s1 to LMQT and start sending group and source specific
> > queries for G1/s1. After LMQT expires Q1 will delete the entry of
> > G1/s1 from its database. Now what will be the non-querier's  
> behaviour.
> > Will it also start LMQT,
>
> Please look at section 6.6.1. When a non-querier receives a query, it
> reduces its corresponding timer to LMQT which can be derived from
> max-response code.
> Suvendu : As per section 8.10, LMQT = LMQC*LMQI, I agree that LMQI is
> the max-response code in the specific query, but LMQC is configurable
> and MAY differ in querier and non-querier. That's where my doubt  
> arises.
>
> > in that case Querier's LMQT and non-querier's LMQT (which is
> > LMQC*LMQI) may differ based on different LMQC values. Non-querier
> > comes to know about the querier's LMQI from the Max Response Code in
> > the specific query pkt but what about querier's LMQC, non-querier  
> has
> > no way to know about the querier's LMQI.
>
> Non-querier does not need to know LMQC as it is not required. LMQC is
> required for a querier to generate number of queries.
> Suvendu : Not only that, LMQC is used in calculating LMQT, pl refer
> section 8.10.
>
> Also most of the times, it is expected that all routers are configured
> with same values but things should still work if they are not.
>
> Hope this helps.
>
> Thanks,
> Bharat
>
>
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> ------------------------------
>
> Message: 3
> Date: Mon, 26 May 2008 19:59:22 +0530
> From: Bharat Joshi <[email protected]>
> Subject: Re: [magma] Non-Querier behaviour on receiving grp specific
>        orgrp-and-src specific queries
> To: Suvendu Mozumdar <[email protected]>
> Cc: "[email protected]" <[email protected]>
> Message-ID:
>
<31D55C4D55BEED48A4459EB64567589A0B27DD9479@BLRKECMBX02.ad.infosys.com 
> >
>
> Content-Type: text/plain;       charset="us-ascii"
>
> Hi Suvendu,
>
> > >      I have an issue for which the RFC 3376 does not suggest  
> anything.
> > > Lets say in a Lan there are two igmpv3 routers and one igmpv3 host
> > > present. Lets say Q1 is querier and Q2 is non-querier. Now Host1  
> sends
> > > include s1 for grp G1. Both Q1 and Q2 will have an entry in their
> > > respective database. Now Host1 sends a report block s1 for grp  
> G1. Q1
> > > on receipt of this block report will start LMQT timer, set the  
> source
> > > timer of s1 to LMQT and start sending group and source specific
> > > queries for G1/s1. After LMQT expires Q1 will delete the entry of
> > > G1/s1 from its database. Now what will be the non-querier's  
> behaviour.
> > > Will it also start LMQT,
> >
> > Please look at section 6.6.1. When a non-querier receives a query,  
> it
> > reduces its corresponding timer to LMQT which can be derived from
> > max-response code.
> > Suvendu : As per section 8.10, LMQT = LMQC*LMQI, I agree that LMQI  
> is
> > the max-response code in the specific query, but LMQC is  
> configurable
> > and MAY differ in querier and non-querier. That's where my doubt  
> arises.
>
> Non-querier need not use LMQT in turn LMQC at all. They can simply  
> lower down their group/source timer to LMQI calculated based on Max- 
> Response-Code and they do it for each group/group-source specific  
> query.
>
> > > in that case Querier's LMQT and non-querier's LMQT (which is
> > > LMQC*LMQI) may differ based on different LMQC values. Non-querier
> > > comes to know about the querier's LMQI from the Max Response  
> Code in
> > > the specific query pkt but what about querier's LMQC, non- 
> querier has
> > > no way to know about the querier's LMQI.
> >
> > Non-querier does not need to know LMQC as it is not required. LMQC  
> is
> > required for a querier to generate number of queries.
> > Suvendu : Not only that, LMQC is used in calculating LMQT, pl refer
> > section 8.10.
>
> Please see above.
>
> Thanks,
> Bharat
>
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> Infosys has taken
> every reasonable precaution to minimize this risk, but is not liable  
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> you may sustain as a result of any virus in this e-mail. You should  
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> own virus checks before opening the e-mail or attachment. Infosys  
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