Subject: [mobile-ip] MH type field

From: Brian Haley <[email-masked]>
Date: Thu, 25 Jul 2002 17:37:41 -0400

I was wondering why the MH type field (Section 6.1.1, draft 18) was 16 bits
and not 8 bits.  I couldn't find any other IPv6 header that had a type larger
than 8 bits, and I don't think we'll ever have 65535 types.  Should this be
changed to 8 bits for type and 8 bits reserved?  This also saves a nthos()
for those of us on certain-endian machines, not that 3 assembly instructions
is buying me anything :)

-Brian

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From: Jari Arkko <[email-masked]>
Date: Fri, 26 Jul 2002 15:24:41 +0300

> for those of us on certain-endian machines, not that 3 assembly instructions

8 bits looks sufficient now. OTOH I don't think the 8 bit reserved field
buys very much either. And there are some protocols in the Internet
where 8 bits looked initially sufficient but proved later to be insufficient.
Mobility is an interesting subject to many folks. Will 256 values cover
all the xMIP extensions that we might need in the future? Yeah, you could
also say that it's a terrible thought that we'd need so much complexity
that 10-15 values wouldn't do...

By the way, if you switch statements in the code are in network byte
order, you'll save the 3 instructions ;-)

My gut feeling is that we should keep the current format, unless
someone has strong arguments otherwise.

Jari