Re: [pim] [MBONED] IGMPv3 backward compatibility issue killing SSM

[Hitoshi Asaeda <[e-mail]>]

Hi Stig,

I’m fine with the following additions.
Thanks.

Regards,

Hitoshi


> On Apr 17, 2024, at 1:08, Stig Venaas <[e-mail]> wrote:
> 
> Hi Brian
> 
> This looks great to me, but I would like to hear from people that
> raise this issue to see if they are OK.
> Toerless, Lenny, Nick, Hitoshi (and others), does this look good to
> you? Can we proceed with the publication?
> 
> Thanks,
> Stig
> 
> 
> On Tue, Apr 16, 2024 at 5:31 AM Brian Haberman <[e-mail]> wrote:
>> 
>> Hi Stig,
>>      Thanks for the clarification...
>> 
>> I am curious if the following two additions would address this issue
>> without delaying the advancement of the documents to Internet Standard.
>> 
>> 1. In Section 7.2.1 - Add this to the last paragraph : "It is
>> recommended that implementers provide a configuration option to disable
>> use of Host Compatibility Mode to allow networks to operate only in SSM
>> mode. This configuration option should be disabled by default."
>> 
>> 2. In Section 7.3.1 - Add an additional bullet : "It is recommended that
>> implementers provide a configuration option to disable use of
>> compatibility mode to allow networks to operate only in SSM mode. This
>> configuration option should be disabled by default."
>> 
>> Regards,
>> Brian
>> 
>> On 4/8/24 5:26 PM, Stig Venaas wrote:
>>> Hi Brian
>>> 
>>> I don't think changing defaults would be sufficient. My concern (and I
>>> think that is what others are concerned about as well) is that hosts
>>> and routers fall back to older versions when there is an older version
>>> querier, as specified in 7.2.1 and 7.3.1. Regardless of the default,
>>> it says that they must change mode or fall back.
>>> 
>>> I think we need some text where we RECOMMEND that hosts and routers
>>> have a knob that disables compatibility mode and makes the host/router
>>> always operate in IGMPv3 mode. This should of course be off by default
>>> (fall back as usual). I'm happy if there is a more lightweight
>>> approach that I'm not seeing.
>>> 
>>> Regards,
>>> Stig
>>> 
>>> On Tue, Apr 2, 2024 at 12:10 PM Brian Haberman <[e-mail]> wrote:
>>>> 
>>>> Hi Hitoshi,
>>>> 
>>>> On 3/20/24 10:01 PM, Hitoshi Asaeda wrote:
>>>>> 
>>>>> I thought what we need to clarify in DS IGMPv3/MLDv2 RFCs is that, as Brian mentioned, we can simply add recommended default settings for the compatibility mode variables. That’s all, I thought.
>>>>> 
>>>>> But you remind me of the following four situations.
>>>>> 
>>>>> 1. querier = SSM capable, forwarder = SSM capable -> no fallback
>>>>> 2. querier = SSM capable, forwarder = non-SSM capable -> fallback
>>>>> 3. querier = non-SSM capable, forwarder = SSM capable -> no fallback (and SSM capable router must become (replace) querier?)
>>>>> 4. querier = non-SSM capable, forwarder = non-SSM capable -> fallback
>>>>> 
>>>>> I wonder how above 2 and 3 are clearly considered in some RFCs?
>>>> 
>>>> Which RFCs are you worried about? I think 3376 and 3376bis cover this in
>>>> section 7.3 with discussion of the compatibility mode and group
>>>> compatibility mode variables. We would augment that discussion with a
>>>> recommendation that those compatibility mode variables default to IGMPv3
>>>> mode.
>>>> 
>>>> Table 9 in section 7.2.1 already indicates that hosts default to IGMPv3
>>>> mode. We need to indicate a similar default in section 7.3.1.
>>>> 
>>>> Regards,
>>>> Brian
>>>> 
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