Hi Shraddha, Authors, et al., I apologize if my question has already been discussed. The unit for the maximum link delay in the draft is a microsecond. There is a group of services that require a highly accurate bounded delay. Have you considered using a nanosecond as the unit for the link delay?
Regards, Greg On Wed, May 19, 2021 at 9:17 PM Shraddha Hegde <shraddha= 40juniper....@dmarc.ietf.org> wrote: > Hi Pengshaofu, > > > > Pls see inline.. > > > > > > Juniper Business Use Only > > *From:* peng.sha...@zte.com.cn <peng.sha...@zte.com.cn> > *Sent:* Thursday, May 20, 2021 7:26 AM > *To:* Shraddha Hegde <shrad...@juniper.net> > *Cc:* acee=40cisco....@dmarc.ietf.org; lsr@ietf.org; > draft-hegde-lsr-flex-algo-bw-...@ietf.org > *Subject:* Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-hegde-lsr-flex-algo-bw-con-02 > > > > *[External Email. Be cautious of content]* > > > > > > Hi Shraddha, > > > > Thanks. Actually, I don't really want to define other metric types. > > Let's go back to the bandwidth-metric related to bandwidth capability. My > worry is that bandwidth-metric (whether it is automatically calculated or > manually configured) is not cumulative in nature, > > <Shraddha> Yes that is correct. > > which is different from IGP default metric/TE metric/delay metric, > > > > so that SPF based on bandwidth-metric may get an unexpected path (see the > example of the original mail). > > Can more text be added in the draft to describe why this can work ? > > <Shraddha> Knowing that metric derived inversely from the link bandwidth > is not additive in nature, should set the expectation right. I can add some > text in this regard. > > > > Regards, > > PSF > > > > > > 原始邮件 > > *发件人：*ShraddhaHegde > > *收件人：*彭少富10053815; > > *抄送人：* > acee=40cisco....@dmarc.ietf.org;lsr@ietf.org;draft-hegde-lsr-flex-algo-bw-...@ietf.org > ; > > *日* *期* *：*2021年05月18日 13:01 > > *主* *题* *：**RE: Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-hegde-lsr-flex-algo-bw-con-02* > > Hi Pengshaofu, > > > > If an operator wants to configure any other metric type draft provides a > mechanism with generic metric. > > Generic metric allows any standard or user-defined type metric to be > configured. > > The draft allows for any computing application such as Flex-algo, CSPF etc > to make use of the > > Metric. The intention of the draft is that for a particular computation > same metric-type is used > > throughout the network. If that is not clear, I’ll add some text in the > draft. > > > > Using a combination of different metrics for a single computation would > need significant change to SPF algorithm and it is not in the scope of the > draft "Flexible Algorithms: Bandwidth, Delay, Metrics and Constraints". > > > > Hope that clarifies. > > > > Rgds > > Shraddha > > > > > > Juniper Business Use Only > > *From:* peng.sha...@zte.com.cn <peng.sha...@zte.com.cn> > *Sent:* Monday, May 17, 2021 12:49 PM > *To:* Shraddha Hegde <shrad...@juniper.net> > *Cc:* acee=40cisco....@dmarc.ietf.org; lsr@ietf.org; > draft-hegde-lsr-flex-algo-bw-...@ietf.org > *Subject:* Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-hegde-lsr-flex-algo-bw-con-02 > > > > *[External Email. Be cautious of content]* > > > > > > Hi Shraddha, > > > > The two methods of automatic generation of BW-metric introduced in the > draft are also likely to be the method of manual configuration of BW-metric > by operators. Operators can certainly manually configure any BW-metric he > wants to configure. > > However, the manually configured BW-metric cannot deviate from the actual > bandwidth capacity of the link, otherwise it could be any other names such > as BX-metric. > > For manual assignment, the problem may still exist We can find an example > that the accumulated bandwidth-metric on the path may offset the manually > increased bandwidth-metric of links on the path. > > Combination of bandwidth attribute of link and other metric that is > cumulative may be another co-exist way to completely address this issue. > > > > Regards, > > PSF > > > > > > > > > > 原始邮件 > > *发件人：*ShraddhaHegde > > *收件人：*彭少富10053815; > > *抄送人：* > acee=40cisco....@dmarc.ietf.org;lsr@ietf.org;draft-hegde-lsr-flex-algo-bw-...@ietf.org > ; > > *日* *期* *：*2021年05月17日 12:15 > > *主* *题* *：**RE: Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-hegde-lsr-flex-algo-bw-con-02* > > Hi Pengshaofu, > > > > I was suggesting to manually assign bandwidth metric which will override > the automatic metric calculation > > as described in the draft section 5. Physically adding more fiber/capacity > is not a feasible solution. > > > > Rgds > > Shraddha > > > > > > Juniper Business Use Only > > *From:* peng.sha...@zte.com.cn <peng.sha...@zte.com.cn> > *Sent:* Monday, May 17, 2021 7:40 AM > *To:* Shraddha Hegde <shrad...@juniper.net> > *Cc:* acee=40cisco....@dmarc.ietf.org; lsr@ietf.org; > draft-hegde-lsr-flex-algo-bw-...@ietf.org > *Subject:* Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-hegde-lsr-flex-algo-bw-con-02 > > > > *[External Email. Be cautious of content]* > > > > > > Hi Shraddha, > > > > Thanks for your rely. > > So it seems that the scheme may lead to the selection of links with less > bandwidth. To address this point, the method as you described to assign > more bandwidth to high bandwidth links seems not always possible, e.g, > adding more fiber ? > > Can this point can be addressed by combination of bandwidth attribute of > link and other metric that is cumulative ? IMO, bandwidth is not cumulative. > > > > Regards > > PSF > > > > 原始邮件 > > *发件人：*ShraddhaHegde > > *收件人：*彭少富10053815; > > *抄送人：* > acee=40cisco....@dmarc.ietf.org;lsr@ietf.org;draft-hegde-lsr-flex-algo-bw-...@ietf.org > ; > > *日* *期* *：*2021年05月13日 21:01 > > *主* *题* *：**RE: Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-hegde-lsr-flex-algo-bw-con-02* > > Hi Peng shaofu, > > > > As per the draft, if automatic metric calculation with reference bandwidth > method is used to calculate the metric > > Then as per your example s->D path will be chosen since metric is 10. > > Lets say operator wants to choose S->X1->X2-àX10->D path then operator > can manually assign higher bandwidth > > Metric on S->D link which will ensure S->D path is not the least cost path. > > > > Rgds > > Shraddha > > > > > > Juniper Business Use Only > > *From:* peng.sha...@zte.com.cn <peng.sha...@zte.com.cn> > *Sent:* Thursday, May 13, 2021 1:05 PM > *To:* peng.sha...@zte.com.cn > *Cc:* acee=40cisco....@dmarc.ietf.org; lsr@ietf.org; > draft-hegde-lsr-flex-algo-bw-...@ietf.org > *Subject:* Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-hegde-lsr-flex-algo-bw-con-02 > > > > *[External Email. Be cautious of content]* > > > > > > Sorry for spelling mistakens in the previous email. > > updated text: > > > > > > Hi WG, > > > > I have a little doubt about the scheme described in this document. > > See the following example: > > > > S ---- X1 ----- X2 ---- ... ... ----- X10 ----- D > > \----------------------------------------------/ > > > > Suppose the links in S---X1---X2...---D have the same bandwidth 10G, and > the link S-D has bandwidth 1G. > > Suppose that we select "reference bandwidth = 100G", then, > > each link in S---X1---X2...---D will have the same bandwidth-metric 10 > (i.e., 100/10) > > link S-D will have a bandwidth-metric 100 (i.e., 100/1) > > > > So flex-algo path from S to D based on bandwidth-metric will be S-D, > not S---X1---X2...---D, because the later has a large cumulative > bandwitdh-metric (i.e., 11*10). > > But our expect path should not be S-D, but S---X1---X2...---D, as it has > large bandwidth. > > Do I misunderstand anything ? > > > > Regards, > > PSF > > > > > > > > > > *发件人：*AceeLindem(acee) > > *收件人：*lsr@ietf.org; > > *抄送人：*draft-hegde-lsr-flex-algo-bw-...@ietf.org; > > *日* *期* *：*2021年05月13日 05:49 > > *主* *题* *：**[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: > Bandwidth, Delay, Metrics and Constraints" - > draft-hegde-lsr-flex-algo-bw-con-02* > > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr > <https://urldefense.com/v3/__https:/www.ietf.org/mailman/listinfo/lsr__;!!NEt6yMaO-gk!TGikk55jVo2FINSWYcGBMe1xnCiMVRlVaOhe77F76PCVbDj893SQ5uuqsL6l_0sA$> > > Esteemed Members of the LSR WG, > > > > This begins a 2 week WG adoption call for the following draft: > > > > https://datatracker.ietf.org/doc/draft-hegde-lsr-flex-algo-bw-con/ > <https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-hegde-lsr-flex-algo-bw-con/__;!!NEt6yMaO-gk!TGikk55jVo2FINSWYcGBMe1xnCiMVRlVaOhe77F76PCVbDj893SQ5uuqsET5yKGD$> > > > > > Please indicate your support or objection by May 27th, 2021. > > > > Authors, please respond to the list indicating whether you are aware of > any IPR that applies to this draft. > > > > Thanks, > > Chris and Acee > > > > > > > > > > > > > _______________________________________________ > Lsr mailing list > Lsr@ietf.org > https://www.ietf.org/mailman/listinfo/lsr >
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