Re: [Netslices] Reliability & Availability in NetSling
Stewart Bryant <stewart.bryant@gmail.com> Mon, 14 August 2017 08:51 UTC
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To: "qiangli (D)" <qiangli3@huawei.com>, "netslices@ietf.org" <netslices@ietf.org>
Cc: Liang Geng | 耿亮 <gengliang@chinamobile.com>, 'Pedro Martinez-Julia' <pedro@nict.go.jp>
References: <06C389826B926F48A557D5DB5A54C4ED2A5743F7@dggemi509-mbs.china.huawei.com> <TY1PR06MB0928FED40F8D136737C6036187880@TY1PR06MB0928.apcprd06.prod.outlook.com> <20170810044200.GB1828@spectre> <17a7e36c-21c7-93ef-8058-573019280dfc@gmail.com> <06C389826B926F48A557D5DB5A54C4ED2A5745E2@dggemi509-mbs.china.huawei.com> <af0cd20c-5747-31bf-cdc7-6af146bf2a87@gmail.com> <06C389826B926F48A557D5DB5A54C4ED2A579B55@dggemi509-mbs.china.huawei.com>
From: Stewart Bryant <stewart.bryant@gmail.com>
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Date: Mon, 14 Aug 2017 09:51:23 +0100
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Subject: Re: [Netslices] Reliability & Availability in NetSling
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Well, we do need a definition to point to even if we reuse an existing definition. That way we all have a common understanding of the term and can provide a common explanation to the tenants. - Stewart On 14/08/2017 04:53, qiangli (D) wrote: > > Hi Stewart and All, > > Thank you for your suggestion. According to your information, it seems > that the words “reliability” is more suitable for the context of > network slicing with SLA guarantee. > > As Liang mentioned, industrial verticals and other partners have > different views on “reliability”. Even within IETF, different WGs may > have different understandings. A standardized definition of > “reliability” in NetSlicing scope is quite necessary IMHO, then NS > service provider can further classify the “reliability” and adopt the > appropriateimplementation technology accordingly. I would like to know > your opinion on this, and do we need to define the slicing specific > “reliability”? > > Best regards, > > Cristina QIANG > > *From:*Stewart Bryant [mailto:stewart.bryant@gmail.com] > *Sent:* Friday, August 11, 2017 4:26 PM > *To:* qiangli (D); netslices@ietf.org > *Subject:* Re: [Netslices] Reliability & Availability in NetSling > > From a tenant's perspective, which arguably is the most important > perspective the key characteristics of interest is surely "The Mean > Time Between Failures (MTBF) to maintain a defined QOS requirement." > together with the duration of those periods. > > With that information you can the viability of your application over > the slice, and the impact on your business. > > - Stewart > > On 11/08/2017 08:47, qiangli (D) wrote: > > Hi All, > > The phrase “working as expected” inspired me. For a network slice, > what people expect is not only the stable working > probability/time, but also the guaranteed SLA. > > Try to consider from tenant’s perspective, I would be very > concerned about how much the promised SLA could really be > achieved. I am not sure which one (availability/reliability) this > concept should belong to according to ITU’s definitions. > > Best regards, > > Cristina QIANG > > *From:*Netslices [mailto:netslices-bounces@ietf.org] *On Behalf Of > *Stewart Bryant > *Sent:* Thursday, August 10, 2017 5:58 PM > *To:* netslices@ietf.org <mailto:netslices@ietf.org> > *Subject:* Re: [Netslices] Reliability & Availability in NetSling > > > In general at IETF we associate reliable with the probability of > packet delivery, and a reliable transport protocol is one that > retries (at a cost of delay) until the packet is delivered or > other factors intervene. Availability tends to refer to the > ability of the network to receive packets for attempted delivery. > > I looked for a formal definition in IPPM which is the WG that is > concerned with measuring such things but could not find a definition. > > From the ITU we can find: > > *Term* : availability (performance) > > *Definition* : The ability of an item to be in a state to perform > a required function under given conditions at a given instant of > time or over a given time interval, assuming that the required > external resources are provided. > NOTE 1 –This ability depends on the combined aspects of the > reliability performance, the maintainability performance and the > maintenance support performance. > NOTE 2 –Required external resources, other than maintenance > resources do not affect the availability performance of the item. > > *Term* : reliability (performance) > > *Definition* : The ability of an item to perform a required > function under given conditions for a given time interval. > NOTE 1 –It is generally assumed that the item is in a state to > perform this required function at the beginning of the time interval. > NOTE 2 –Generally, reliability performance is quantified using > appropriate measures. In some applications, these measures include > an expression of reliability performance as a probability, which > is also called reliability. > > > or > > *Term* : reliability characteristic > > *Definition* : The Mean Time Between Failures (MTBF) to maintain a > defined QOS requirement. > > > - Stewart > > On 10/08/2017 05:42, Pedro Martinez-Julia wrote: > > Dear all, > > I personally think it is better to use the industrial > definitions but, > > being purist, we can find important differences between them. > While > > availability is the probability for a system to work as > expected in some > > period of time (99.999% of time), reliability is a broader > term that > > refers to the different situations in which a system will be > able to > > overcome without breaking. In some cases, the latter can > incorporate the > > former, but not in all of them. > > For network slicing we can keep the definition commonly used > by industry > > with the necessary details to make clear the aspects that > differentiate > > them. I would keep "working as expected for some period of > time" related > > to availability and "resistant to disparate situations" to > reliability. > > Regards, > > Pedro > > On Thu, Aug 10, 2017 at 02:44:09AM +0000, GENG Liang wrote: > > Hi Cristina, > > Interestingly we were discussing this confusion with few > industrial partners recently. In telecommunication > language we normally use "Reliability" to refer the > probability a network is stably run (i.e. 99.999% of > time). This is also regarded as network "Availability". > However, "Reliability" in industrial verticals is more > comprehensive - including not only network availability > parameter but also mechanics, electricity etc. > > Personally I think, network slicing is still looking at > network regime where I believe Reliability means the > percentage of time a connection is available. But we you > sell this concept to industrial verticals, they may think > differently. > > ________________________________ > > Liang GENG > > China Mobile Research Institute > > From: qiangli (D)<mailto:qiangli3@huawei.com> > <mailto:qiangli3@huawei.com> > > Date: 2017-08-10 10:04 > > To: netslices@ietf.org > <mailto:netslices@ietf.org><mailto:netslices@ietf.org> > <mailto:netslices@ietf.org> > > Subject: [Netslices] Reliability & Availability in NetSling > > Hi All, > > I was confused when I was reading some NetSlicing related > materials. It seems that “Reliability”supported by Netslicing refers to the probability that a > network slice could work stably, or other similar metrics. > But, shouldn’t this be the defination of “Availability”? Then what does reliability mean in NetSlicing? > > Best regards, > > Cristina QIANG > > _______________________________________________ > > Netslices mailing list > > Netslices@ietf.org <mailto:Netslices@ietf.org> > > https://www.ietf.org/mailman/listinfo/netslices >
- [Netslices] Reliability & Availability in NetSling qiangli (D)
- Re: [Netslices] Reliability & Availability in Net… GENG Liang
- Re: [Netslices] Reliability & Availability in Net… Pedro Martinez-Julia
- Re: [Netslices] Reliability & Availability in Net… Stewart Bryant
- Re: [Netslices] Reliability & Availability in Net… qiangli (D)
- Re: [Netslices] Reliability & Availability in Net… Stewart Bryant
- Re: [Netslices] Reliability & Availability in Net… qiangli (D)
- Re: [Netslices] Reliability & Availability in Net… Stewart Bryant