Re: [spring] WG Adoption Call for draft-dong-spring-sr-for-enhanced-vpn

"Dongjie (Jimmy)" <> Tue, 09 February 2021 06:46 UTC

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From: "Dongjie (Jimmy)" <>
To: Shunsuke Homma <>, James Guichard <>
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Thread-Topic: [spring] WG Adoption Call for draft-dong-spring-sr-for-enhanced-vpn
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Date: Tue, 9 Feb 2021 06:46:49 +0000
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Subject: Re: [spring] WG Adoption Call for draft-dong-spring-sr-for-enhanced-vpn
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Hi Shunsuke,

Thanks a lot for your review and comments. Please see some replies inline:

From: spring [] On Behalf Of Shunsuke Homma
Sent: Tuesday, February 9, 2021 12:05 AM
To: James Guichard <>
Subject: Re: [spring] WG Adoption Call for draft-dong-spring-sr-for-enhanced-vpn

Hi WG,

I think that this document is good enough as starting point for the WG, and I support the adoption. There are many drafts related to network slice with SR (e.g., SR + Flex-algo, draft-bestbar-spring-scalable-ns, etc.) and I hope it will be clarified which is the best in future work.

[Jie] Thanks for your support.

The following are my comments to the draft.
- The example describes three isolated VTNs. I assume (hard) isolation will cause split loss, and oversubscription will be sometimes needed. Hence, it may be better to allow a resource-aware SID to belong to multiple VTNs.

[Jie] In the context of SR based VTN, each resource-aware SID is associated with one VTN. Multiple services which are mapped to the same VTN can use the same group of SIDs to guide the packet forwarding, thus  a resource-aware SID and the associated resources can be shared by multiple services.

- From network slicing (i.e., NaaS model) perspective, I assume visibility will be especially important. As one more important requirement, network operators want to provide only information of the VTN whose customer uses to that customer. For example, if a customer gets VTN information with BGP-LS, some mechanisms to prevent to leak other VTNs information in BGP-LS would be needed.

[Jie] Yes, depends on the operator’s policy, the amount and the granularity of information exposed to a customer should be controlled. The considerations about this is described in section 3.5 VTN Visibility to Customer. The required control plane mechanism can be based on  BGP-LS mechanism in RFC7752 (and the in progress draft-7752bis), some extension may be introduced if needed.

- There is a typo in figure2. The adj-SID of the link from 203 to 204 in green VTN should be 2002.

[Jie] Thanks for catching the typo. We will fix it in next revision.

Best regards,



On Wed, Jan 27, 2021 at 8:47 PM James Guichard <<>> wrote:
Dear WG:

This message starts a 2 week WG adoption call for ending February 10th 2021.

After review of the document please indicate support (or not) for WG adoption to the mailing list and if you are willing to work on the document, please state this explicitly. This gives the chairs an indication of the energy level of people in the working group willing to work on this document. Please also provide comments/reasons for your support (or lack thereof) as this is a stronger way to indicate your (non) support as this is not a vote.


Jim, Bruno & Joel

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