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
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