Subject: [rbridge] Options MT Bit Question

From: "David Michael Bond" <[email-masked]>
Date: Wed, 2 Jun 2010 23:27:17 -0400

I just had a question behind the motivation for the MT bit in
draft-ietf-trill-rbridge-options-00.

Since each option type will define whether or not its mutable can't this
information be implicitly discovered from the options type? Is there any
reason for a transit rbridge that does not understand an ItoE option to
change a mutable option?

I am just curious whether this needs to be sent over the wire or if this
could be reserved for another purpose.
Thanks,
David

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From: Donald Eastlake <[email-masked]>
Date: Wed, 2 Jun 2010 23:52:20 -0400

The reason for the MT bit is so that you could practically define an
Ingress-to-Egress TRILL security option. Such an option should protect the
value of all immutable ItoE options but not any mutable values. Without the
MT bit, you would have to update the security option every time you added a
new ItoE option type.

Thanks,
Donald
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