Subject: RE: MIPv6 and ND value changes

From: "Bound, Jim" <[email-masked]>
Date: Mon, 18 Nov 2002 23:56:22 -0500

> > http://www.piuha.net/~jarkko/publications/mipv6/issues/issue79.txt

I just want to point out that Francis and Vlad in the above both are
implemetors not rubber neckers and both work in IPv6 WG and MIPv6 WG so
the expertise is in both groups (Thomas this is one example why I think
IPv6 WG is covered).  Same for Brian Haley, Carl Williams, Alper
Yegin....etc etc.
So lets not at least be under the illusion that MIPv6 does not have IPv6
WG expertise that is simply bogus.

/jim

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From: Francis Dupont <[email-masked]>
Date: Tue, 19 Nov 2002 18:14:36 +0100

implemetors ...

=> as my name occurs in this thread where my opinion is nicely represented
by Erik, I often asked that the ND discussion was moved from the MIP list
to the IPng/IPv6 list.
About some points, IMHO the fast RA is not a good idea because its impact
on a regular network can be very high. I can summarize this in RAs are
not good beacons. But for instance the R bit (i.e., put the router address
in place of the prefix) is a good thing, and not only in the MIPv6 context.

Regards

[email-masked]

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From: Vijay Devarapalli <[email-masked]>
Date: Tue, 19 Nov 2002 09:47:21 -0800

Francis,

> on a regular network can be very high. I can summarize this in RAs are

MIPv6 does not say router should send RAs more frequently. it 
just says access routers SHOULD be configurable to send RAs 
more frequently. this is to be used in the absense of any L2 
help.

Vijay

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From: Francis Dupont <[email-masked]>
Date: Tue, 19 Nov 2002 19:38:03 +0100

more frequently.

=> We know this is translated in many minds in the first statement...
And this doesn't change the argument that RAs are poor beacons.

   this is to be used in the absense of any L2 help.
   
=> this shows the function is to beacon.

Regards

PS: my purpose is not to contribute to this thread!

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From: Erik Nordmark <[email-masked]>
Date: Wed, 20 Nov 2002 21:48:00 +0100 (CET)

> more frequently. this is to be used in the absense of any L2 

Vijay,

One part of the problem I see is that your last sentence above doesn't
appear in the draft. Getting the applicability of the frequent unsolicited
RAs stated is important.
Doing this in a short separate draft doesn't have to delay the mipv6
spec, but working out the text before the mipv6 spec get last called
will add delay as far as I can tell.

  Erik

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From: Vijay Devarapalli <[email-masked]>
Date: Wed, 20 Nov 2002 13:31:00 -0800

> will add delay as far as I can tell.

Hi Erik,

the applicability of frequent RAs can be specified in 1 sentence.
"if you have a bandwidth constrained link, dont depend on frequent 
RAs for movement detection". do we need a separate spec for this?

Vijay

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From: Richard Nelson <[email-masked]>
Date: Thu, 21 Nov 2002 11:42:30 +0000

The draft covers this quite well near the end of section 7.5.  It talks
specifically about low bandwidth networks which maybe could be expanded
to include any network where L2 support is available, but I think the
intent is pretty clear.  

Richard.

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From: Michael Thomas <[email-masked]>
Date: Wed, 20 Nov 2002 18:02:19 -0800 (PST)

So I listened to this argument for a very long
time (too long) yesterday wondering what on earth
the big deal was. I still don't get it. If people
want to dial up the ND rate, it only hurts their
link. There's no greater internet impact that I
can see. If it's taking up too much bandwidth, a
sniffer would show it pretty quickly and you turn
the knob down, so wo cares?

That said, I do think this is a pretty poor
substitute for L2 information which probably
should be making its way up the driver. 

	  Mike

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From: Francis Dupont <[email-masked]>
Date: Thu, 21 Nov 2002 15:18:31 +0100

=> I agree but I have a concern to get this in an unclear spec,
i.e., as a network manager, I'd not like to get request to put
silly RA timing because it is written somewhere.

=> 100% agree

Regards

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From: Charlie Perkins <[email-masked]>
Date: Thu, 21 Nov 2002 07:25:27 -0800

Hello Francis,

Francis Dupont wrote:

> I agree but I have a concern to get this in an unclear spec,

We certainly don't want an unclear specification.  And, if a
network manager needs to support mobile nodes on any
local domains, that network manager needs in many circumstances
to have the information that running more frequent advertisements
is advisable.

Can you suggest a way to make the specification more clear?

>    should be making its way up the driver.

It is well known for many years that using layer-2 information
makes for better movement detection.

However, when that option is not available, our experience and
that of many others shows that the faster beaconing is effective
and can be applied without any surprises.

There have been numerous papers published about this, which
led to the appropriate specification for Mobile IPv4.  The situation
for Mobile IPv6 is not any different.

Regards,
Charlie P.

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From: Francis Dupont <[email-masked]>
Date: Thu, 21 Nov 2002 23:30:51 +0100

=> I don't want to use frequent RAs on my network because there is
an 802.11 AP on it (APs are L2 bridges).

=> last chance solutions should be marked and never get more than
a MAY.

=> another concern is RAs are bad beacons...

=> I'd really like to get a spec without surprise applicable
in my fast Ethernet LAN with 5 routers, 50 hosts and 2 APs.
BTW there are 3 prefixes on it (multi-homed between two ISPs).

Regards

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From: Charlie Perkins <[email-masked]>
Date: Thu, 21 Nov 2002 19:10:32 -0800

>  => last chance solutions should be marked and never get more than

Indeed, the frequency parameter is tunable.  There is no specification
that one HAS to use the advertisement as a beacon.  You should only
do this if it is suitable for your networks.  You MAY use the fast rate,
you are not in any way mandated to do so.

Regards,
Charlie P.