Subject: RFC2461(bis): normativeness of protocol constants

From: Pekka Savola <[email-masked]>
Date: Sat, 23 Dec 2006 17:36:12 +0200 (EET)

Hi,

Speaking of RFC 2461(bis), some time ago I noticed the following 
behaviour with a popular router implementation (a support case is open 
on this): for forwarded packets, it takes up to 24 hours (in recent 
software versions, up to 20 minutes) for the hardware forwarding to 
notice that an IP address moved from one link-layer address to another 
on the same link if unsolicited NAs (section 7.2.6, only an 
optimization; few host implementations seem to send these) are not 
sent by the hosts.

My reading of the spec is that this is not compliant with RFC2461, 
where protocol constants are REACHABLE_TIME (30s) and 
DELAY_FIRST_PROBE_TIME (5s) -- unreachability detection could take 
about 35 times longer than the spec.

However, the spec doesn't say whether the defined protocol constants 
are normative, and this could be explicitly stated if that's deemed a 
necessary addition.

Any thoughts?

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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From: Brian Haberman <[email-masked]>
Date: Thu, 28 Dec 2006 09:04:37 -0500

Pekka Savola wrote:
> optimization; few host implementations seem to send these) are not sent
> by the hosts.
> 
> My reading of the spec is that this is not compliant with RFC2461, where
> protocol constants are REACHABLE_TIME (30s) and DELAY_FIRST_PROBE_TIME
> (5s) -- unreachability detection could take about 35 times longer than
> the spec.
> 
> However, the spec doesn't say whether the defined protocol constants are
> normative, and this could be explicitly stated if that's deemed a
> necessary addition.
> 
> Any thoughts?
> 

Given that 2461 (and 2461bis) are DS, I would find it very disturbing if
implementers did not treat the entire document as normative.  In order
to be compliant with a spec (any spec), an implementation MUST adhere to
all aspects including protocol constants.  Otherwise, how would we ever
have interoperability?  I do not see any benefit in having any
specification state *which* components of the document are normative.

Regards,
Brian