Re: [Supa] Comments on draft-contreras-supa-yang-network-topo-00

[Tina TSOU <[e-mail]>]

Dear Martin,

We discussed off-line how the supa topology draft is related to the i2rs topology draft, I feel it is worthy to bring it to the list for broader audience.

This draft http://datatracker.ietf.org/doc/draft-hares-i2rs-info-model-service-topo/ also focused on network topology information model which is also within the scope of SUPA topology model. However, besides the common interests at topology model, there are still significant differences between the two.

1.       The I2RS topology model is based on a service topology which is closely related to certain service. And the service topology can be dedicated to one tenant or multiple tenants. For SUPA, different layers have different views or representations of the same network topology. Multiple users may not "share" the same topology but use their own topology at their own layer.



2.       The I2RS topology model use service topologies which should be independent from network topology and therefore should not map onto other underlay topologies. The SUPA topology model is a unified topology model to support service at all levels. Each level can have its own representation of the topology.


3.     There is no YANG based topology model in this I2RS draft yet. SUPA has a well defined YANG data model to describe the topology.

All in all, the two drafts have something in common and the basic principals are very close. IMO, service topology can be one use case for SUPA topology model to be used in BGP, OSPF and so on.


Thank you,
Tina

From: Supa [mailto:[e-mail]] On Behalf Of Tina TSOU
Sent: Sunday, September 28, 2014 12:30 PM
To: LUIS MIGUEL CONTRERAS MURILLO; [e-mail]
Cc: [e-mail]
Subject: [Supa] Comments on draft-contreras-supa-yang-network-topo-00

Dear Luis, Andrew et al,

Thank you for writing such a concrete model.

I read draft-contreras-supa-yang-network-topo-00<http://datatracker.ietf.org/doc/draft-contreras-supa-yang-network-topo/>. It is well written. Below are some comments.

The basic idea of this draft is very good, and I can understand what the author tries to say. However still, more clarification is needed especially for some definitions.

1.         In section 4.2, there are "virtual node" and "container node", what is difference between these two kinds of nodes? For the virtual node, it is more understandable that it is the virtualization of the physical node or nodes. But for the container node, it can be a group of nodes or only one node. What is the necessity to define such a container node, is it domain specific or a general idea for all the use cases?



2.         Would you elaborate one use case for the container node? In order to demonstrate the insufficiency of virtual node to cover the application or use cases, show one use case that the container node idea is necessary.


3.      In section 4.2, there is also some external links or nodes definition, what is the purpose for that? Are they external for the user or the up level controller?


4.       In first figure of section 4
                  +-------------------------+
                  |                         |
                  |       topology          |
                  |                         |
                  +-+-+----+---------+--+-+-+
                    | |    |         |  | |
                    | |    |         |  | |
                    | |    |         |  | |
                    | |    |         |  | |
      +------------+ |    |         |  | |
       |              |    |         |  | +------------------+
       |        +-----+    |         |  +--------+           |
       |        |          |         +-+         |           |
       |        |          |           |         |           |
    +--+---+ +--+---+ +----+------++---+---+ +---+---+ +-----+-----+
    |link  | |node  | |termination||extLink| |extNode| |extTerminat|
    +------+ +------+ |Point      |+-------+ +-------+ |ionPoint   |
                      +-----------+                    +-----------+

How can the unified topology be mapped into different applications or users? I guess you need to map this topology, if this is the only one topology, to different applications in order to make it work.


Thank you,
Tina