Re: [OSPF] draft-ietf-ospf-yang-03 questions and doubts

"Acee Lindem (acee)" <acee@cisco.com> Fri, 13 May 2016 14:02 UTC

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From: "Acee Lindem (acee)" <acee@cisco.com>
To: "t.petch" <ietfc@btconnect.com>, Alan Davey <Alan.Davey@metaswitch.com>, "Derek Man-Kit Yeung (myeung)" <myeung@cisco.com>, "draft-ietf-ospf-yang@ietf.org" <draft-ietf-ospf-yang@ietf.org>
Thread-Topic: [OSPF] draft-ietf-ospf-yang-03 questions and doubts
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Date: Fri, 13 May 2016 14:02:27 +0000
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Cc: OSPF WG List <ospf@ietf.org>
Subject: Re: [OSPF] draft-ietf-ospf-yang-03 questions and doubts
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Hi Tom, 

On 5/12/16, 1:41 PM, "OSPF on behalf of t.petch" <ospf-bounces@ietf.org on
behalf of ietfc@btconnect.com> wrote:

>----- Original Message -----
>From: "Alan Davey" <Alan.Davey@metaswitch.com>
>To: "Derek Man-Kit Yeung (myeung)" <myeung@cisco.com>om>;
><draft-ietf-ospf-yang@ietf.org>
>Cc: "OSPF WG List" <ospf@ietf.org>
>Sent: Wednesday, May 11, 2016 5:40 PM
>
>Hi Derek
>
>A question about the key for OSPF interfaces in the Yang draft.  Please
>let me know what you think.
>
>The background is that the Management Information Base definitions
>define indices for OSPF interfaces as follows.
>
>
>-          For OSPFv2, RFC 4750 defines the index as ospfIfIpAddress,
>ospfAddressLessIf.
>
>-          For OSPFv3, RFC 5643 defines the index as ospfv3IfIndex,
>ospfv3IfInstId.
>
>However, in the OSPF Yang draft, the key is defined as "interface",
>which I believe is a name of the interface.
>
>How does "interface" map to the indices defined in RFCs 4750 and 5643?
>
><tp>
>
>It doesn't (IMHO).  You have two lists of interfaces in this I-D
>
>container interfaces { description "All interfaces."; list interface {
>key "interface";
>description "List of OSPF interfaces.";
>
>container interfaces { description "All interfaces in the area.";  list
>interface { key "interface";
>description "List of OSPF interfaces.";
>
>both keyed on 'interface' (which is two separate lists so two separate
>'interface' leaf, different sets of key objects.).

These are basically the same lists - one is for operational state and the
other is for configuration.


>
>Both are defined as
>
>     type if:interface-ref;
>
>and the if: harks back to
>     import ietf-interfaces {prefix "if";
>and ietf-interfaces is in RFC7223 where interface-ref is defined as
>"   An interface is identified by its name, which is unique within the
>   server.  This property is captured in the "interface-ref" and
>   "interface-state-ref" typedefs, which other YANG modules SHOULD use
>   when they need to reference a configured interface or operationally
>   used interface, respectively."
>
>So both lists are keyed on a name which is unique within the server and
>can be anything, such as 'lan0' or 'fast-ethernet-23/7' or
>'hotplug23/6/15' or... It all depends; names may be dictated by the
>hardware with no choice, or they may be dictated by the software to
>compliant hardware or ...
>
>Underlying this is the thought that we have no good definition of an
>interface, one that works across all protocols and other aspects of a
>configuration; an interface is like a blob of jelly and pinning it down
>to be a name is about as good a grasp of it as we will get (IMO).

Agreed. 

Thanks,
Acee 



>
>Tom Petch
>
>Thanks
>Alan
>
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