Re: globally unique identifiers for lightpaths?

[Ronald van der Pol <Ronald.vanderPol@xxxxxxxx>]

On Thu, Dec 06, 2007 at 19:26:29 +0100, Erik-Jan Bos wrote:

> Hi Ronald and Dave:
> 
> I too support the global naming of lightpath. As one of the "design
> criteria" I think it should adhere to the KISS principle as much as
> possible.

About KISS: you know I fully agree :-)

> Hence, I think that the system we come up with should:
> * Ensure uniqueness.

Two possibilities, I think:
- central repository
- random number

I prefer the latter.

> * Be maintenance free as much as possible (i.e. a name should not change
> when one of the characteristics of the lightpath changes).

Do you think the name should remain the same when the lightpath
is re-routed? That rules out an identifier which lists all
the GOLEs or all the local names in the path.

I am not sure. It is convenient to be able to deduct the topology
of a lightpath by looking at the name. If we do not do this, we
really need a good inter-domain monitoring system setup fast.
That system must provide domain and topology info for each lightpath.

> * Avoid any notion of a central authority or repository.
> * Be able to generate a name on the spot by an organization (i.e.
> without going back and forth with one or more peer organizations).

I agree. How about these options:
- generate a random number of X digits
	this will be a unique ID when X is large enough
- take the current time in UTC
	YYYYMMDDHHMMSS, e.g. 20071206200042
	It is highly unlikely that two lightpaths get created at the
	same second

I prefer the latter. I does not need a random number generator program.
Just look at your watch to create this number.

At the moment, my preferred ID would look like this:

YYYYMMDDHHMMSS-GOLE1-GOLE2

GOLE1 and GOLE2 are UN Location codes (http://www.unece.org/cefact/locode/)

Examples:
20071205200042-AMS-CHI
20071206070809-NYC-TYO

- it is easy to parse because it has a fixed format (22 bytes)
- the number YYYYMMDDHHMMSS ensures uniqueness, especially in combination
  with the two locodes
- it gives the egress and ingress GOLE and thus some kind of topology info

	rvdp