Re: [Supa] Network Topology Data Model and Network Configration Data Model

["Wunan (Eric)" <[e-mail]>]

Hi Juergen,

Reply in line.

Regards
Eric

________________________________________
发件人: Juergen Schoenwaelder [[e-mail]]
发送时间: 2014年11月12日 4:15
收件人: Wunan (Eric)
抄送: [e-mail]; Tina TSOU
主题: Re: [Supa] Network Topology Data Model and Network Configration Data Model

On Tue, Nov 11, 2014 at 08:04:33PM +0000, Wunan (Eric) wrote:
>
>
> In the IP world, we usually talk about nodes, links, and interfaces.
> And interfaces have been generalized to cover multiple layers. Is
> there a specific reason why you prefer the term 'TerminationPoint'?
> How is a 'TerminationPoint' different from an interface (and what
> is the relationship between them)?
>
> [Eric]: As the draft said, network topology DM is supposed to be defined in a hierachy manner.
>
> When "IP world" is the concern, we are acutally talking about the topology DM for IP.
>
> You are right that people are more familar with "interface", I am.
>
> Actually in the IP Topology DM, "TerminationPoint" is interface.
>
> Per my understanding, this word may be prefered because network topology is not only focusing on IP.
>
> As you know some protocols don't have to depend on "interface", they got their own vacabulary.
>
> For example, IS-IS was using "circuit" and VLAN got "port".
>
> When speaking "interface", i feel it will be more proper when CLI is used.

A VLAN port is just another interface. See the IF-MIB or the
ietf-interfaces YANG model or the IANA interface registry. If a
TerminationPoint is just a different name for 'interface', then I
clearly prefer to stick to terms we are all familiar with.

[Eric]: I think VLAN port's definition use IF-MIB's defined type, but port is not the interface directly in VLAN MIB.

I think this is what you are talking about:



   Dot1dBasePortEntry ::=
       SEQUENCE {
           dot1dBasePort
               Integer32,
           dot1dBasePortIfIndex
               InterfaceIndex,                               -----------------interface
           dot1dBasePortCircuit
               OBJECT IDENTIFIER,
           dot1dBasePortDelayExceededDiscards
               Counter32,
           dot1dBasePortMtuExceededDiscards
               Counter32
       }

> What is the difference of this topology data model from other
> proposals on the table, such as draft-clemm-i2rs-yang-network-topo-01
> and draft-hares-i2rs-info-model-service-topo-01 (there there might
> be more)?
>
> [Eric]: I would say both of them are talking about topology data model.
>
> One difference may be the position they are used in the architecture.
>
> For draft-hares-i2rs-info-model-service-topo-01,
>
> I think it is the topology for service, another layer in the hierarchy.

I was hoping for a more technical answer. Why do we need N topology
data models? If I look at the YANG snippets, I do not see what makes
them specific to a 'position in the architecture'.

[Eric]: Of course it is not because the "position" only. Actually not at all.

For the I2RS model you mentioned, i think it mainly focus on the IP/IGP topology.

While the conception i got from the draft-contreras-supa-yang-network-topo-01,

it tried to define one hierarchy for topology.

Plus it contains some extXXX definition in the model, which don't catched in I2RS topo.

I think it may have some consideration behind this. Maybe the authors can talk more about this.

Based on that currently I won't suggest to reuse I2RS YANG model directly in the SUPA scenario.

/js

--
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: [phone]         Campus Ring 1, 28759 Bremen, Germany
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