[Nsi-wg] Some thoughts on STP

[Jeff W. Boote]

Agree completely.

jeff

On Apr 14, 2011, at 8:15 AM, Jeroen van der Ham wrote:

> Hello,
> 
> Please allow me to bundle my feedback on the identifier scheme
> discussion. A short summary of the issue as I see them currently:
> There needs to be a globally unique identifier for Service Termination
> Points. This id does not have to be related to a point in a network
> topology, but the local NSA must be able to map an STP id to a service
> and/or endpoint in the network.
> 
> One possible solution: "The identifier can be just a string"
> I would strongly argue against this line of thought. Strings are not
> simple objects. There is a very valid reason why the definition of urn
> identifiers for OGF (and NML) takes up half a dozen pages. The
> construction and equality of strings is not trivial to define and should
> not be underestimated.
> 
> I am very much in favor of urn-style identifiers similar in style to
> what GLIF is using currently, using
> urn:<identifier>:<network-name>:<localpart>.
> 
> The <identifier> is the urn namespace, most easily is to use a
> subnamespace of the ogf, urn:ogf:nsi: springs to mind.
> The advantage of this is that it is easy to set up, constraints on
> content and equality are already provided and reasonably clear to users.
> 
> The <network-name> can be the DNS namespace that the NSA represents.
> This also allows you to use a simple out-of-band verification of the NSA
> using DNS TXT records or something.
> 
> The <localpart> can then be defined by the local NSA itself, and it has
> complete freedom to define this within the confines of the urn syntax
> limits as described for the namespace.
> 
> The whole system allows for a very simple scheme that makes it
> immediately obvious what the identifier is for, and easily ensures
> global uniqueness. Knowing the purpose of the identifier is important
> because these will probably be used in many different contexts, as they
> are used as advertisement of the service.
> 
> The identifiers may become a bit long, but given the fact that the NSI
> protocol seems to converge on XML as a dataformat, I do not feel that
> string-lengths is a problem.
> 
> One last point on VLAN identification:
> I have seen some examples where the VLAN number is part of the
> identifier. There is also an argument for STPs to not map to the network
> topology so as to avoid a problem with 4095 different labels.
> As far as I know right now NML will not create labels for endpoints for
> each different VLAN, wavelength, timeslot or whatever. This should
> become a property of the object the identifier identifies, not part of
> the identifier itself.
> 
> Jeroen.
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