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



Hi Greg,

----- Original Message ----- 
From: "Greg Daley" <greg.daley@eng.monash.edu.au>
To: "Syam Madanapalli" <syam@samsung.com>
Cc: "Pekka Savola" <pekkas@netcore.fi>; <ipv6@ietf.org>; "Soohong Daniel
Park" <soohong.park@samsung.com>; <jinmei@isl.rdc.toshiba.co.jp>
Sent: Thursday, August 12, 2004 8:19 AM
Subject: 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
> than

Yep, I agree. Using the smaller MTU one will be more safer.
But  it may be efficient to use the advertised MTU
when the packet is destined for that particualr router because
these two routers might have connected to different networks
and the these routers may support different MTUs based on
their hardware capabilities.


>
> 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.

So you agree to maintain M/O flags per router basis and
R1:M | R2:M|...|Rn:M = 1 means DHCPv6 Server available
on the network?
Similarly for O flag.


>
> Greg
>
>


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