Re: Linux & draft-gont-6man-slaac-dns-config-issues

[Fernando Gont <[e-mail]>]

Hi, Jen,

On 03/25/2015 06:46 AM, Jen Linkova wrote:
> On Wed, Mar 25, 2015 at 12:12 AM, Fernando Gont <[e-mail]> wrote:
>> On 03/24/2015 12:24 PM, Jen Linkova wrote:
>>> On Tue, Mar 24, 2015 at 5:22 PM, Fernando Gont <[e-mail]> wrote:
>>>>> I agree that "<= 2x MaxRtrAdvInterval" limitation is way too strict
>>>>> and we SHOULD fix this.
>>
>> It is not a network misconfiguration. It's a bug in the spec.
> 
> Again, I totally agree that the lifetime value probably should not be
> limited to 2x MaxRtrAdvInterval
> and it should be fixed. However I strongly object updating RFC6106 with
> 'The default value of AdvRDNSSLifetime and AdvDNSSLLifetime MUST be at
> least 10*MaxRtrAdvInterval'.
> I think we shall remove "<2x MaxRtrAdvInterval" limitation in 6106, that's it.

Fair enough. Although there are two issues here:

1) Allowed bounds
2) Default value


For #1, removing the upper bound is good enough. But there's still #2.


> Bounding it to "> 10x MaxRtrAdvInterval" seems to be unnecessary overkill.
> 
> BTW most of the router implementations I've seen do allow specifying
> lifetime values > 2MaxRtrAdvInterval, so I do believe that in many
> cases the problem you are describing could be solved by properly
> configuring routers.

Yes. Thing here is that we should have:

1) Sane defaults
2) The spec should allow for configuring sane Lifetime values


>>> And yes, it might be equal to Router Lifetime, which might be
>>> significantly lower than 6000 sec (1 hr 40 mins) you are proposing.
>>
>> I think that the specific value that we use is the low-order bit (I can
>> certainly live with 6000 sec). The high order bit is that there is a
>> problem to be fixed.
> 
> I want be able to configure machines with lifetime much lower than
> 6000 secs, that's my problem with this draft.

Fair enough. But the *default* value should be something that actually
works, even if you don't know what you're doing.

Cheers,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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