Re: [dtn] BPv7 node ID and node identity

[[e-mail]]

Hi, Brian.  A couple of answers, which may or may not be helpful:

1.	This is a recent change, responding to objections that disallowing
demuxes (for the dtn scheme) and non-zero service numbers (for the ipn
scheme) in the source node ID was unnecessarily restrictive - the identity
of the node could be accurately determined by inspection even if those rules
were violated.  The BPv7 specification has been revised to state that any
endpoint ID from which the identity of the node can be discerned without
consulting any other information source may serve as a node ID.  This is
sort of by definition - it's a string that identifies the node, so it's a
node ID, even if it contains some additional information that identifies a
particular endpoint in which that node is registered.  (Nodes have in fact
always been able to have multiple administrative endpoints, hence multiple
node ID strings, i.e., one for the dtn scheme and another for the ipn
scheme.)
2.	It is not required that a node be identifiable only by a single EID.
3.	The ID of an administrative endpoint of a node may always be used to
identify the node; such endpoints implicitly exist so long as the node
itself exists.  (That is, if and only if a node exists it is registered in
its administrative endpoint(s).)  Other EIDs may serve as node IDs as well -
in particular, they may be cited as the sources of bundles - but the
identified endpoints are not guaranteed to be in existence at any particular
moment.  (Nodes may register and unregister in other singleton endpoints at
will.)

 

Scott

 

From: dtn <[e-mail]> On Behalf Of Sipos, Brian J.
Sent: Friday, December 3, 2021 12:55 PM
To: [e-mail]
Subject: [dtn] BPv7 node ID and node identity

 

All,

After re-reading some of the to-be-RFC 9171 I realize that I had been making
an incorrect assumption for a long time: that the administrative endpoint ID
of a node is the same as its node ID. I see now that more technically that
EID can be the node ID but doesn't have to be. In that light I have some
deeper questions about a node and its node ID:

1.	Is it operational practice that the administrative EID is in fact
the node ID? Early examples that I read led me to expect this.
2.	Is it required that a node has only a single node ID at any
point-in-time? In many parts of the document (and other documents and
discussions) the phrasing is ". the node ID ." and not ". a node ID ." or
similar phrasing.
3.	Is it expected or required that a node ID be stable over time for a
node? If not, there seem to be operational issues related to how peers can
identify a node with a time-varying node ID. This is especially the case
with respect to node authentication and how an authority may grant
identifier use to a node.

 

These questions are coming up in the context of the "Node ID Validation"
document [1] and its assumptions that the answer to all the above questions
are "yes." There are definitely parts of that document which are ambiguous
or incorrect now that I see it with the perspective that a node ID is not
equivalent to the administrative EID.

 

Thanks for any clarification,

Brian S.

 

[1] https://www.ietf.org/archive/id/draft-ietf-acme-dtnnodeid-07.html