Subject: [Ipoverib] please read: Clarification on GUID's universal/local bit

From: "H.K. Jerry Chu" <[email-masked]>
Date: Sun, 23 May 2004 12:22:08 -0700 (PDT)

A question was raised during the IESG review of the encapsulation
and multicast draft

http://www.ietf.org/internet-drafts/draft-ietf-ipoib-ip-over-infiniband-06.txt

regarding the use of GUID as an interface identifier.

IPv6 spec (RFC2373 and RFC3513) requires, when an interface identifier
is derived from an IEEE EUI-64 identifier, that the universal/local bit to
be inverted. The following is quoted from RFC3513:

"Modified EUI-64 format interface identifiers are formed by inverting
the "u" bit (universal/local bit in IEEE EUI-64 terminology) when
forming the interface identifier from IEEE EUI-64 identifiers.	In
the resulting Modified EUI-64 format the "u" bit is set to one (1) to
indicate global scope, and it is set to zero (0) to indicate local
scope."

IBA spec Vol1 Release 1.1 Nov 6, 2002, section 4.1 states

EUI-64: IEEE defined 64-bit identifier...

*	The universal/local bit in IEEE EUI-64 shall be set to one to
	indicate global scope or set to zero to indicate local scope.
	The manufacturer assigns an EUI-64 with global scope set. A SM
	may assign additional EUI-64 with local scope indicated.

According to Dan Cassiday, the IBTA LWG chair, the above paragraph
clearly implies that a GUID has the universal/local bit inverted already
from an EUI-64 identifier, and thus can be readily used as an IPv6
interface identifier.

I'd like to hear, especially from those IB hardware manufacturers,
if the above is consistent with your implementation. That is, the
GUIDs you provide will have universal/local bit set to 1.

Separately if you think the IBA spec should be made more clear above
the relation between GUID and EUI-64, you should submit your suggestion
to IBTA.

Thank you,

Jerry

IPoIB WG co-chair

[email-masked]
Sr. Staff Engineer
Solaris Networking & Security Technology
Sun Microsystems, Inc.
(650) 786-5146

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