Peoples,
I understand the usefulness of having a release command from a networking
Jerry, If you have maintenance, the resources are unavailable. This is either scheduled and system should not book resources in that time, or forced by situation which is a failure for NSI (cancel/reroute/reprovision). This must be simple. There is a lot of questions from non-NSI people on what is the release and what is it purpose. The only case I can imagine is when the link is shared by provisioned and best effort traffic, so releasing connection can speed up best-effort, no-guaranteed traffic for a while. Reprovisioning will decrease the bandwidth for best-effort traffic without much damage. How likely is that to happen? Is the regular IP traffic so high we need to clear on-demand connections whenever possible? If I booked the resources, I am paying for them despite of the fact I am using them currently or not. Release gives some flexibility and may have some use cases, but IMHO for sake of simplicity we should make it optional or get rid of it at all. Best regards Radek ----------------------------------------------------------- Radek Krzywania e-mail: radek.krzywania@man.poznan.pl phone: +48 61 850 2526 Network R&D Poznan Supercomputing and Networking Center Noskowskiego 12/14 61-704 Poznan Poland -----Original Message----- From: nsi-wg-bounces@ogf.org [mailto:nsi-wg-bounces@ogf.org] On Behalf Of Jerry Sobieski Sent: Thursday, February 28, 2013 12:14 AM To: John MacAuley Cc: nsi-wg@ogf.org Group Subject: Re: [Nsi-wg] Release command Hi John - I know a number of implementations that have not implemented the Modify() command - and probably won't either. So lets remove it also. If you really want to simplify the protocol and SMs, get rid of Modify. :-) but seriously... Use cases and historical context: Many connections will be in service over weeks, months or years. The idea is to be able to drop the circuit from its "in service" state without releasing the reserved resources back to the available pool and risk those resources being allocated to other Connections. The potential for new reservations locking out or substantially changing the existing reservation was deemed unacceptable. The circuit could be re-provisioned as long as it was still within the reservation window. The use case would be for periodic maintenance where the circuit would be affected but where the interruption is expected and should not constitute an error. Another use case can be where the reserved resources in one domain for a connection need to be modified (say a link is upgraded from 10 G to 100 G) - but the upstream or downstream domain resources should not be released back to the availability pool. When the circuit data plane is broken there is no way to guaranty the privacy or security or reliability of user data - the Release enables the user to halt traffic and allow the circuit to be fiddled with.... The other domains should not generate alarms or otherwise act as if the connection is fully functional - but its not an error either. Release is not just a cosmetic command. I do not think there was an intention to modify the circuit as-built characteristics during a release - Indeed, I think the intent was to simply communicate to all NSAs in the tree that the data plane can be interupted without causing an "outage" or triggering alarms all up and down the path. So while we probably did not document in sufficient detail what the user would experience as result of a release and re-provision, the sentiment was that the circuit would be "essentially" the same after reprovisioning. (e.g. "The expected performance characteristics should be the same before and after a Release.") I do recall the discussion where we stipulated that the data flow *should* be actively blocked during a Release since to admit user data without confirmation that all segments were in service would pose a security and reliability flaw to the performance guarantees. However, I do not think anything about curtailing the flow at ingress made it into the spec. A) Why is this difficult to implement? B) To my recollection, the Release() was never considered an "optional" primitive in terms of implementation, just that it could be skipped in the life cycle protocol sequence thus allowing an active circuit to go directly to a Cancel state without passing through Released. (This means only that the protocol can skip the Release action in cases where it is not needed - not that it is an optional primitive in an NSI CS implementation.) So if it is not implemented I would consider it an incomplete implementation. C) What behaviour are you thinking the Release is or is not doing? Or doing incorrectly? This seems like a new proposal when we are trying to curtail any additional changes - particularly major changes which I think this is. I think we should retain the Release() primitive in its current form for v2. WE can revisit the issue in v3 ? just my thoughts.. Jerry On 2/27/13 12:38 PM, John MacAuley wrote: perspective, but I know a number of implementations are not supporting it at the moment (and some have no intention of supporting it). With my new "lets make the state machine as simple as possible attitude" I started to wonder what is the customer use case for this command? Chin had one where someone wanted to keep their reservation, but wanted to free up bandwidth for others to use. This is an interesting use case, but not the behaviour of the current command as documented. Removal of this command can significantly simplify the protocol and state machine.
Would it be possible for people to provide their customer use cases for
this command? I am wondering if it is truly needed, or perhaps, we have the incorrect behaviour defined.
Thank you, John _______________________________________________ nsi-wg mailing list nsi-wg@ogf.org https://www.ogf.org/mailman/listinfo/nsi-wg
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