Re: [Lsr] LSR WG Adoption Poll for "Flexible Algorithms: Bandwidth, Delay, Metrics and Constraints" - draft-hegde-lsr-flex-algo-bw-con-02

[Shraddha Hegde <[e-mail]>]

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



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To: Shraddha Hegde <[e-mail]>
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Subject: Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: Bandwidth, Delay, Metrics and Constraints" - draft-hegde-lsr-flex-algo-bw-con-02

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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=[e-mail];[e-mail];[e-mail]<mailto:acee=[e-mail];[e-mail];[e-mail]>;
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



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Sent: Monday, May 17, 2021 7:40 AM
To: Shraddha Hegde <[e-mail]<mailto:[e-mail]>>
Cc: acee=[e-mail]<mailto:acee=[e-mail]>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: Bandwidth, Delay, Metrics and Constraints" - draft-hegde-lsr-flex-algo-bw-con-02

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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=[e-mail];[e-mail];[e-mail]<mailto:acee=[e-mail];[e-mail];[e-mail]>;
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--->X10->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



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Sent: Thursday, May 13, 2021 1:05 PM
To: [e-mail]<mailto:[e-mail]>
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Subject: Re:[Lsr] LSR WG Adoption Poll for "Flexible Algorithms: Bandwidth, Delay, Metrics and Constraints" - draft-hegde-lsr-flex-algo-bw-con-02

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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：[e-mail]<mailto:[e-mail]>;
抄送人：[e-mail]<mailto:[e-mail]>;
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
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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$>

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