Hello,
At OGF 33 in Lyon we discussed the potential problem that
urn:ogf:network identifiers are somewhat volatile.
The IETF requires that URN must never be re-assigned or re-used. The
currently proposed syntax (and prior practice) uses domain names to
identify the organisation that assigned a URN. Domain names may be
re-assigned, so there is a risk that URNs in the proposed syntax may be
re-assigned or re-used.
I personally consider identifier collisions unlikely, but possible in
archives with historic measurement data.
The participants in the OGF 33 discussion generally agreed that we
should look into fixing this.
The usual solution to prevent identifier collisions is to set up a
registry that assigns prefixes. E.g. IANA has a registry for URN
namespaces, ICANN for top level domain names, CNRI has a registry for
the Handle system, etc.
Most of the discussion was aimed how to create a registry within the
OGF. A few possible identifiers that identify the organisation that
assigns URNs were discussed:
- DNS name - the current syntax. e.g. "sara.nl"
- organisation name - e.g. "SARA"
- DNS + version - e.g. "sara.nl:1"
- DNS + year - e.g. "sara.nl:2011"
I personally hope it is possible to re-use an existing registry, so that
the OGF does not need to create a registry on its own. Examples of
current registries are AS-numbers and DNS.
- DNS can be used, but is consider volatile. (RFC 3406 explicitly
states that domain names "makes a poor URN namespace in practice")
- AS-number do not work, since not all organisations that want to
assign urn:ogf:network identifiers have a AS number (e.g. many
Dutch universities do not have their own AS number as they only
have one upstream provider, SURFnet).
Of the above examples,
- organisation name - e.g. "SARA"
- DNS + version - e.g. "sara.nl:1"
require a new registry within the OGF
- DNS name - e.g. "sara.nl"
is considered volatile
I claim that using a domain name + year
1) is not volatile
2) does not require a new registry within the OGF
A domain name is volatile because it can be reassigned. However, a
domain name is typically not re-assigned within a year (if only because
registration fees are usually paid per year, not per month). Hence, the
combination of year and domain name is a unique identifier for an
organisation.
Hence, I propose the following syntax for urn:ogf:network identifiers
(in ABFR format):
"urn:ogf:network:" DOMAINNAME ":" ASSIGNINGYEAR ":" SNSS
where
DOMAINNAME = a FQDN that is administratively owned by the organisation
that assigns the URN
ASSIGNINGYEAR = year (gregorian calendar) whent he URN is first
assigned (note that once a URN is assigned, this number does not change
for that URN.)
SNSS = subnamespace specific string. The remainder of the URN that
only has meaning for the assigning organisation and should not be
interpreted by other organisations.
Regards,
Freek
