Subject: [mobile-ip] Mobile Routers: Why is P bit needed?

From: "T.J. Kniveton" <[email-masked]>
Date: Fri, 10 Aug 2001 10:34:56 +0100

There is one question I had on the Mobile Networks draft which I thought
would be better suited for the list than the meeting:

What is the need for a Prefix Scope Registration bit? I can not think of
a case where a MR would have to include a Prefix Scope extension on a BU
and wouldn't want it to be processed. Isn't the inclusion of said
extension, or not, tantamount to indicating its presence with the P bit?

-TJ

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From: Alexandru Petrescu <[email-masked]>
Date: 12 Aug 2001 09:44:06 +0200

"T.J. Kniveton" <[email-masked]> writes:
> What is the need for a Prefix Scope Registration bit? I can not
> think of a case where a MR would have to include a Prefix Scope
> extension on a BU and wouldn't want it to be processed. Isn't the
> inclusion of said extension, or not, tantamount to indicating its
> presence with the P bit?

I think yes, having a Mobile Network Prefix Sub-Option type set aside
as a distinctive value eliminates the need for the P bit.  Moreover, I
think it's better to extend the BU first with specific sub-options and
to touch the Reservd field as late as possible.

Other parts of the draft rely a lot on this P bit, but I think the P
bit could simply be deduced from the presence of the respective
sub-option type.

Alex

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From: Thierry Ernst <[email-masked]>
Date: Mon, 13 Aug 2001 17:18:29 +0200

> extension, or not, tantamount to indicating its presence with the P bit?

May be the 'P' bit is not needed.    I put it there as an indication for
the receiver to check if a Mobile Network Prefix sub-option is needed or
not.

Thierry.

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