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Re: [mpls] Use of leaf-lists in draft-ietf-mpls-static-yang

"Tarek Saad (tsaad)" <tsaad@cisco.com> Fri, 31 March 2017 13:53 UTC

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From: "Tarek Saad (tsaad)" <tsaad@cisco.com>
To: Aidan Copeland <aidan.copeland@metaswitch.com>, "draft-ietf-mpls-static-yang@ietf.org" <draft-ietf-mpls-static-yang@ietf.org>, "mpls@ietf.org" <mpls@ietf.org>
Thread-Topic: Use of leaf-lists in draft-ietf-mpls-static-yang
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Date: Fri, 31 Mar 2017 13:53:50 +0000
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Subject: Re: [mpls] Use of leaf-lists in draft-ietf-mpls-static-yang
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Hi Aidan,

You are right. Indeed, it is permissible the same labels values can repeat in the label stack and thus the leaf-list is not suitable. I’ll look into this and we’ll update it the model.
Thanks for reporting it.

Regards,
Tarek

On 2017-03-29, 10:30 AM, "Aidan Copeland" <aidan.copeland@metaswitch.com<mailto:aidan.copeland@metaswitch.com>> wrote:

Hi Tarek, all,

I think that there is an error in the use of a leaf-list to represent the set of outgoing MPLS labels to impose for an outgoing path.

RFC7950, section 7.7, states

In configuration data, the values in a leaf-list MUST be unique.

This means that a leaf-list is not suitable to represent a label stack, where the same label value may be used more than once.

I think the best solution is instead to specify the set of outgoing labels as a list of outgoing label containers, keyed by label index and containing the outgoing label value.

Do you agree with this, or do you think a different mechanism would be better?

Regards

Aidan

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