I agree with Joel,

To answer Linda's question: if I2RS agent manages/represnts multiple physical 
devices, the interface between the agent and the devices is out of scope of 
I2RS. Note that such interface needs to be standardized only if one considers a 
scenario where an I2RS agent controls devices from different vendors. IMHO this 
scenario is unlikely, and at least for now it is safe to assume that said 
interface is private.

Cheers,
Igor

-----Original Message-----
From: i2rs [mailto:[email protected]] On Behalf Of Joel M. Halpern
Sent: Monday, June 29, 2015 2:01 PM
To: Linda Dunbar; Juergen Schoenwaelder
Cc: [email protected]; '[email protected]'; [email protected]; Hariharan 
Ananthakrishnan; [email protected]; [email protected]; Jan Medved (jmedved)
Subject: Re: [i2rs] comments to draft-ietf-i2rs-yang-network-topo-01

Juergen is correct that by the I2RS definition an I2RS Agent is part of, and 
associated with, a single routing element.

It is true that the routing element may itself be a controller supporting and 
interacting with multiple forwarding elements.  That is not required, and not 
discussed, by I2RS.  As far as I2RS is concerned, the multiplicity is that the 
relationship between I2RS Clittns and I2rS agents is N:M.  That is, a client 
may be working with multiple agents, 
and an agent may be communicating with multiple clients.   But it is 
still the case that the agent is collocated with the routing system, and is not 
in a separate controller from the routing system.

Yours,
Joel

On 6/29/15 10:46 AM, Linda Dunbar wrote:
> Juergen,
>
> One I2RS agent can interface with multiple routing elements.
>
> The network view (which consists of multiple nodes, i.e. topology) has to be 
> over multiple nodes. Therefore, it is the interface between client and Agent. 
> Whereas, there are commands to individual routing element.
>
> Linda
> -----Original Message-----
> From: Juergen Schoenwaelder 
> [mailto:[email protected]]
> Sent: Monday, June 29, 2015 3:28 AM
> To: Linda Dunbar
> Cc: '[email protected]'; [email protected]; Jan Medved (jmedved); 
> [email protected]; [email protected]; Hariharan Ananthakrishnan; 
> [email protected]
> Subject: Re: [i2rs] comments to draft-ietf-i2rs-yang-network-topo-01
>
> Linda,
>
> according to draft-ietf-i2rs-architecture-09, an I2RS agent is part of a 
> routing element. I am not sure your understanding "I2RS Agent is like the SDN 
> controller" is consistent with the architecture document.
>
> /js
>
> On Fri, Jun 26, 2015 at 05:03:25PM +0000, Linda Dunbar wrote:
>> Alex, et al,
>>
>> The I2RS architecture depicts two types of interfaces:
>>
>> -          One is the interface between Agent and Client, and
>>
>> -          another is the interface between Agent and Routing entities.
>>
>>
>> The network model and inventory are more for the interface between Agent and 
>> the Clients,  isn't it? One single routing engine doesn't need to know the 
>> overall topology and inventory information of other nodes, even though some 
>> may do.
>>
>>
>> And the /nd:network/nd:node and Termination points are more for the 
>> interface between the Agent and the Forwarding Engine, isn't it?
>>
>> IMHO, the information models should be oriented around the I2RS 
>> architecture. I.e. with description on where those information models are 
>> applicable, making it easier to differentiate from other IETF WGs work (such 
>> as L2VPN, L3VPN, or SFC). I recall there were some debates at the Dallas 
>> I2RS session.
>>
>> I2RS Agent is like the SDN controller, which can inform clients about the 
>> topology information, instruct routes to routing engine of multiple nodes, 
>> and retrieve link & termination points status from each of those nodes.
>>
>> The "Service Overlay" in Section 3.4.8 is definitely meant for clients not 
>> towards individual nodes. Mixing them all together make it confusing.
>>
>> Cheers,
>>
>> Linda Dunbar
>>
>>
>
>> _______________________________________________
>> i2rs mailing list
>> [email protected]
>> https://www.ietf.org/mailman/listinfo/i2rs
>
>

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