[Nsi-wg] Topology virtualisation

[Freek Dijkstra]

Gigi Karmous-Edwards wrote:

> [...] during path computation I remove all non-GOLE domains from the global topology graph [...]

I am curious why you made this choice. Path computation can take any of these constraints into account:
- topology constraints (is there a connection?)
- technology constraints (is it compatible?)
- usage constraints (is it available?)
- policy constraints (may it be used?)

Looking at the Internet, BGP is only concerned with the first and last constraint (topology and policy). Let's assume for a moment that in optical networks these are also the most important constraints, then GOLE is much less relevant for path finding (only topology is relevant as it has no policy on its own) than an other domain (topology and policy to take into account). Based on that, I would argue that it is better to leave out the GOLEs and only take other domains into account.

Since you do the exact opposite (ignoring non-GOLEs), I presume you argue that other constraints are the ones that matter.

Given the other mails, I presume that you only look at topology constraints, ignoring policy, technology and usage constraints.

If so, I have two questions:
1. Is there a specific reason why you think that policy, technology and usage constraints can be ignored?
2. Why do you think that topology constraints can be ignored for non-GOLEs? Do you perhaps assume that non-GOLE topologies will never be connected to more than one or two GOLEs and never be connected to a non-GOLE directly? Is this true for larger backbone networks such as GEANT, NLR and Internet2 (I presume that Internet2 is connected to Pacific Wave, StarLight and MAN LAN).

Regards,
Freek