Re: [ipv6mib] Discontinuity timer for TCP-MIB counters

[Rajiv Raghunarayan <raraghun at cisco.com>]

Hi Juergen,

Thanks for the feedback. My comments inline.

Juergen Schoenwaelder wrote:
> > > > > > Rajiv Raghunarayan writes:
>
> Rajiv> The IESG review suggested that we provide a discontinuity timer
> Rajiv> for the counters in the mib - could be via sysUpTime or a new
> Rajiv> discontinuity object. But we state it either way. 
> Here are my 3 thoughs on this:
>
> 1) So far, sysUpTime has been used by the existing TCP-MIB objects.
>    Introducing a new discontinuity indicator now raises the question
>    whether doing so breaks existing implementations.
Yep. It would probably break implementations if 2) were to be an
incorrect assumption for any implementation. Else, I think we
shouldn't be affecting other implementations (but those case wouldn't
need a separate discontinuity indicator as well!)?

> 2) Personally, I doubt that there will be many implementations where
>    TCP can experience discontinuities that do not also affect other
>    parts of the networking stack or the whole system.
I suspected that, but wasn't sure.

> 3) I do see the problem that sysUpTime might be more frequently reset
>    as we like due to some other MIBs which do not use explicit
>    discontinuity indicators and experience more frequent
>    resets. However, the root of the problem is then really in those
>    MIBs, not in the TCP-MIB. (Sure, by introducing a discontinuity
>    indicator for the TCP-MIB we can protect against other misbehaving
>    MIBs - but is this going to set a precedence which at the end
>    requires a CLR that better every MIB module has at least one,
>    perhaps multiple discontinuity indicators?)
Agreed.

> In the case of the TCP-MIB, I believe 1) is the killing argument. To
> introduce a new discontinuity indicator changes the implicit semantics
> of existing objects and would require to introduce new objects, which
> I think is prohibitive.
>
> Conclusion: Spell out that sysUpTime is used as a discontinuity
> indicator for the counters.
I've modified the mib to indicate it - will submit the mib, if I do
not receive any arguments to the contrary in the next couple of days.

Thanks,
Rajiv.

> /js

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