Subject: [mpls] Comments on draft-ietf-mpls-sfc-01

From: "Andrew G. Malis" <[email-masked]>
Date: Wed, 23 May 2018 15:52:13 -0400

Adrian et al,

I just had a chance to review draft-ietf-mpls-sfc-01 in detail, and have a
few comments.

First of all, thanks for including the section 4.5 text.

That said, I’m having a hard time distinguishing between using MPLS-SR for
SFC and the “micro chains” discussed in section 4.4. I agree that the
“micro chains" are a logical extreme of section 4.2, but that said, section
4.2 does include swapping as well as popping, while section 4.4 is pure
popping. It would be greatly appreciated if you could add text that
differentiates “micro chains” from MPLS-SR, otherwise it’s just a different
name for the same functionality. If there is actually is no difference,
then section 4.4 should be removed.

I also have a comment in section 12. The text currently says "It should be
noted that the MPLS encoding is slightly less functional than the direct
use of the NSH.” In this case, “slightly” is a judgement for the reader to
make, and I see a huge loss of functionality because there’s no support for
per-packet metadata. Please remove the word “slightly” in this text.
Without the word “slightly”, the text changes from an opinion to a fact.

Thanks,
Andy

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From: "徐小虎(义先)" <[email-masked]>
Date: Thu, 24 May 2018 13:25:31 +0800

It's hard for me to understand the difference between the MPLS-SR-based SFC approach as referred to in section 4.5 and the "micro chains" discussed in section 4.4 as well.
Best regards,Xiaohu
------------------------------------------------------------------From:Andrew G. Malis <[email-masked]>Send Time:2018年5月24日(星期四) 03:52To:draft-ietf-mpls-sfc <[email-masked]>Cc:mpls <[email-masked]>; sfc <[email-masked]>Subject:[mpls] Comments on draft-ietf-mpls-sfc-01
Adrian et al,
I just had a chance to review draft-ietf-mpls-sfc-01 in detail, and have a few comments.
First of all, thanks for including the section 4.5 text.
That said, I’m having a hard time distinguishing between using MPLS-SR for SFC and the “micro chains” discussed in section 4.4. I agree that the “micro chains" are a logical extreme of section 4.2, but that said, section 4.2 does include swapping as well as popping, while section 4.4 is pure popping. It would be greatly appreciated if you could add text that differentiates “micro chains” from MPLS-SR, otherwise it’s just a different name for the same functionality. If there is actually is no difference, then section 4.4 should be removed.
I also have a comment in section 12. The text currently says "It should be noted that the MPLS encoding is slightly less functional than the direct use of the NSH.” In this case, “slightly” is a judgement for the reader to make, and I see a huge loss of functionality because there’s no support for per-packet metadata. Please remove the word “slightly” in this text. Without the word “slightly”, the text changes from an opinion to a fact.
Thanks,Andy

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From: "Zafar Ali (zali)" <[email-masked]>
Date: Sat, 26 May 2018 16:16:17 +0000

Dear authors of draft-ietf-mpls-sfc and the WG,

I agree with Andy and Xiaohu.  I also do not find any difference in the “micro chains” as described in Section 4.4 and SR-MPLS based approach for SFC. I think this section should either be removed or should merely add a normative reference to I-D.xuclad-spring-sr-service-chaining.

Thanks

Regards … Zafar

From: sfc <[email-masked]> on behalf of "徐小虎(义先)" <[email-masked]>
Reply-To: "徐小虎(义先)" <[email-masked]>
Date: Thursday, May 24, 2018 at 1:26 AM
To: mpls <[email-masked]>, draft-ietf-mpls-sfc <[email-masked]>
Cc: "[email-masked]" <[email-masked]>, sfc <[email-masked]>
Subject: Re: [sfc] [mpls] Comments on draft-ietf-mpls-sfc-01

Best regards,
Xiaohu

------------------------------------------------------------------
From:Andrew G. Malis <[email-masked]>
Send Time:2018年5月24日(星期四) 03:52
To:draft-ietf-mpls-sfc <[email-masked]>
Cc:mpls <[email-masked]>; sfc <[email-masked]>
Subject:[mpls] Comments on draft-ietf-mpls-sfc-01

Adrian et al,

Thanks,
Andy