Re: IGMP Non Querier - Querier Transition

Hi RajaSekhar,

                     When a non-qurier becomes a querier, it should always
use configured query interval and in absense of a configured value default
should be used.

Thanks,
Indranil
On Tue, Nov 10, 2009 at 12:28 PM, rajasekar bonthala <
[email protected]> wrote:

> RFC 3376 says that IGMP Non-Querier should adopt the robustness and Query
> interval from the Querier.
> Those sections are pasted below for reference.
>
> 4.1.6. QRV (Querier’s Robustness Variable)
>
> If non-zero, the QRV field contains the [Robustness Variable] value
>
> used by the querier, i.e., the sender of the Query. If the querier’s
>
> [Robustness Variable] exceeds 7, the maximum value of the QRV field,
>
> the QRV is set to zero. Routers adopt the QRV value from the most
>
> recently received Query as their own [Robustness Variable] value,
>
> unless that most recently received QRV was zero, in which case the
>
> receivers use the default [Robustness Variable] value specified in
>
> section 8.1 or a statically configured value.
>
> 4.1.7. QQIC (Querier’s Query Interval Code)
>
> The Querier’s Query Interval Code field specifies the [Query
>
> Interval] used by the querier. The actual interval, called the
>
> Querier’s Query Interval (QQI), is represented in units of seconds
>
> and is derived from the Querier’s Query Interval Code as follows:
>
> If QQIC < 128, QQI = QQIC
>
> If QQIC >= 128, QQIC represents a floating-point value as follows:
>
> 0 1 2 3 4 5 6 7
>
> +-+-+-+-+-+-+-+-+
>
> |1| exp | mant |
>
> +-+-+-+-+-+-+-+-+
>
> QQI = (mant | 0x10) << (exp + 3)
>
> Multicast routers that are not the current querier adopt the QQI
>
> value from the most recently received Query as their own [Query
>
> Interval] value, unless that most recently received QQI was zero, in
>
> which case the receiving routers use the default [Query Interval]
> value specified in section 8.2.
>
>
>
>
> The above sections says that these values need to adopted as their own
> values.
> But the RFC does not explain on whether the Non-Querier should continue
> with the adopted values,when transitions to Querier state (if the existing
> querier is down due to any reason).
>
> Can any one please clarify me on this.
>
> Thanks,
> RajaSekhar
>
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>

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