Subject: [mobile-ip] Mipv6 issue #175: MH Type space split?

From: Jari Arkko <[email-masked]>
Date: Fri, 29 Nov 2002 13:32:51 +0200

Thomas Narten asks about the MH Type space:

 > Does it make sense to split the option type space into ranges, where <
 > 128 means silently ignore, >=128 send back an error? This might be
 > useful in the future ...

I think we discussed this in the past. It appears that most things
we want to do can be done without an explicit error code. For instance,
when adding new security mechanisms beyond RR, a request message can
include an option, and if the peer supports this option, it will also
return an option in the response message. Both nodes will therefore
know whether the peer supported their options or not.

Of course, this might not be sufficient in all cases; for instance, if
there are options in the response message that the receiver HAS to
understand, currently we have no way of indicating it.

I guess this is a design tradeoff: we can add the range scheme and
related error code. Or, we can design our future extensions in a way
that this will not be a problem. I'm willing to do this either way,
but the current thinking is that we should rather keep the scheme simple
than make it work efficiently in all possible future scenarios.

Jari