Hi Jeff and Xufeng,
Sorry, catching up on this thread. Yes, we've made a change for the MPLS label-stack from "leaf-list" to a "list with key index" to address having multiple labels of same value in the same stack. We noted an assumption in the description that index 0 is the top of the stack followed by the remainder of the labels in the stack. However, you have a point about enforcing index (n-1) being present before accepting index n. There is some discussion on 'preceding-sibling' and 'following-sibling' with some recommendations in rfc6087.. I'll need to check if enforcing such "when" check is good idea in YANG. Another idea (not so elegant) is relax this "index 0 as top" and just accept the lowest index of the list as the top followed by the remainder labels (as sorted in index increasing order). Regards, Tarek -----Original Message----- From: Jeffrey Haas <[email protected]> Date: Thursday, July 13, 2017 at 12:51 PM To: Xufeng Liu <[email protected]> Cc: Greg Mirsky <[email protected]>, "[email protected]" <[email protected]>, "[email protected]" <[email protected]>, "[email protected]" <[email protected]>, "[email protected]" <[email protected]> Subject: Re: MPLS label and LSE data models Resent-From: <[email protected]> Resent-To: Tarek Saad <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]> Resent-Date: Thursday, July 13, 2017 at 12:42 PM Xufeng, On Thu, Jul 13, 2017 at 04:14:18PM +0000, Xufeng Liu wrote: > Thanks for looking at this. You are right, but we are still discussing various approaches for the static MPLS and the conclusion has not been reached yet. > We'd like to hear what you think and appreciate your comments. To offer a suggestion, order the stack from bottom (lowest number) to top (highest). Require that bottom of stack be element index zero. My yang constraints are a bit weak but I believe you can construct an XPath that requires that a node of index 0 must be present. The above two suggestions don't help with the issues of needing to sort the list by index in order to generate the stack, but it does at least remove any possible ambiguity about the critical bottom of stack semantic. -- Jeff
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