Re: [magma] Query on querier version in IGMPv3

Hi Bharat,

              The first part is applicable to a router which has v3 but has
been configured as v2.

               The 'reselection' part was an answer for when the router
should revert back to the configured higher query version. This will
be done when transmitting general query. After that if it receives v2/v1
query then it will lower the version again. Even if you take the new timer
approach, problem is that how do you control sequence of queries from
routers? Say, after timer expiry version is changed and v3 GQ is sent. V2
non-querier does not understand v3 query so it sends v2 GQ.

                Section 7.3.1 says that it is an administrative
responsibility. Excerpt is given below:
"If any older versions of IGMP are present on routers, the querier
     MUST use the lowest version of IGMP present on the network.  This
     must be administratively assured; routers that desire to be
     compatible with IGMPv1 and IGMPv2 MUST have a configuration option
     to act in IGMPv1 or IGMPv2 compatibility modes."

Thanks,
Indranil

On Mon, Jul 19, 2010 at 1:45 PM, Bharat Joshi <bharat_joshi@infosys.com>wrote:

> Indranil,
>
>     Ok. But RFC 3376 clearly says that a router should lower its version to
> the lowest version of query heard on a network.
>
>     One thing I did not get in your reply is 'Let the v2 updates's it
> querier timer from v3 query...'. While second part of this statement is
> clear, I am not sure about the first part. A version 2 querier may/may not
> support V3 so things won't work any way and there will be multiple number of
> queries on network which may not be desirable.
>
>     Another thing I did not understand is the last sentence. What do you
> mean by 'reselection can happen after every general query'? I think RFC 3376
> suggested this to avoid multiple queries on a network. If a router do what
> is suggested in RFC 3376, at least there will be only one query in the
> network.
>
>     I checked couple of open-source implementation and it seems none of
> them store this information and always use the highest configured version to
> send out an IGMP query. Not sure if there was any specific reason for not
> doing this.
>
> Regards,
> Bharat
> ________________________________________
> From: Indranil Bhattacharya [myselfindranil@gmail.com]
> Sent: Monday, July 19, 2010 1:43 PM
> To: Bharat Joshi
> Cc: magma@ietf.org
> Subject: Re: [magma] Query on querier version in IGMPv3
>
> Hi Bharat,
>
>              Do not lower the querier version. Let the v2 updates's it
> querier timer from v3 query or let it use it's configured query interval.
> Otherwise, the reselection can happen after every General query.
>
> Thanks,
> Indranil
>
>  On Mon, Jul 19, 2010 at 10:39 AM, Bharat Joshi <bharat_joshi@infosys.com
> <mailto:bharat_joshi@infosys.com>> wrote:
> Hi All,
>
>     I was re-reading RFC 3376 for handling compatibility for lower version
> of querier.
>
>     In section 7.3.1, it is mentioned that a querier configured to run in
> V3 mode
>     should lower its version when it sees a lower version query on the same
>     network. From that time onwards, a router should send the lower version
>     queries.
>
>     Now the question is, when this router should revert back to its
> configured higher
>     version? The text in section 7.3.1 or elsewhere does not talk about
> this.
>
>     Should a timer 'lower_version_querier' be started and updated as and
> when lower
>     version queries are removed? Please note this is not same as
> other-querier-present
>     timer.
>
>     Can someone, who has implemented IGMPv3, let me know how this
> particular case
>     has been handled in their implementation?
>
> Regards,
> Bharat
> **************** CAUTION - Disclaimer *****************
> This e-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended
> solely
> for the use of the addressee(s). If you are not the intended recipient,
> please
> notify the sender by e-mail and delete the original message. Further, you
> are not
> to copy, disclose, or distribute this e-mail or its contents to any other
> person and
> any such actions are unlawful. This e-mail may contain viruses. Infosys has
> taken
> every reasonable precaution to minimize this risk, but is not liable for
> any damage
> you may sustain as a result of any virus in this e-mail. You should carry
> out your
> own virus checks before opening the e-mail or attachment. Infosys reserves
> the
> right to monitor and review the content of all messages sent to or from
> this e-mail
> address. Messages sent to or from this e-mail address may be stored on the
> Infosys e-mail system.
> ***INFOSYS******** End of Disclaimer ********INFOSYS***
> _______________________________________________
> magma mailing list
> magma@ietf.org<mailto:magma@ietf.org>
>  https://www.ietf.org/mailman/listinfo/magma
>
>