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Re: comments on draft-daniel-ipv6-ra-mo-flags-00.txt

Hi Syam,

Syam Madanapalli wrote:
> ----- Original Message ----- 
> From: "Pekka Savola" <pekkas@netcore.fi>
> To: "Syam Madanapalli" <syam@samsung.com>
> Cc: <jinmei@isl.rdc.toshiba.co.jp>; <ipv6@ietf.org>; "Soohong Daniel Park"
> <soohong.park@samsung.com>
> Sent: Wednesday, August 11, 2004 2:20 AM
> Subject: Re: comments on draft-daniel-ipv6-ra-mo-flags-00.txt
>>On Tue, 10 Aug 2004, Syam Madanapalli wrote:
>>>M/O flags indicate the avaialbility of the respective service, so if
>>>a router advertises the M/O flags bits ON, I think we should OFF
>>>them if and only if the same router advertises again to OFF. It is
>>>administartor problem if one advertises with bits ON, and other
>>>router with bits OFF.
>>How do you propose the host keeps track of which router advertised
>>which bits?  This kind of tracking is not done at the moment.
> True, this requires one needs maintain the M/O flags information per router
> basis. And this leads to implementation complexity. But I think this method
> provides robust implemention. I am not sure how people are managing if
> two different routers on same link advertises two different Link MTU. I
> think the problem could be similar in both the cases.

Indeed it is similar.

When you have trusted routers with differing configurations,
you have to make a decision what configuration to undertake.

For MTU, it's clear that you need to take the smallest
(most restrictive) value advertised.  This is because
choice of a higher MTU is likely to have worse effects

For DHC it's not the same choice, although it requires similar
decision path.  In DHC, any M or O flag set indicates that
there is a DHC server available (albeit it may provide
only limited function).

In this case, the host can use a DHC server if any of the trusted
routers advertises this capability.  In this case,
the scenario is least restrictive, rather than most restrictive.

Certainly the routers should advertise consistent values,
but the hosts should make reasonable decisions even if
the routers disagree.


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