You may recall that I have expressed concern about many times about how
the network topology draft fits the I2RS scope. It is still not clear
to me that it is an I2RS item, although it is clearly useful for things
talking to the I2RS Agent.
Yours,
Joel
On 6/29/15 5:01 PM, Linda Dunbar wrote:
Joel, Igor, Juergen,
Thanks for the feedback. Actually I always thought I2RS Agent is within a single routing
engine until reading the "I2RS Topology" draft.
I see draft-ietf-i2rs-rib-info-model-06 as a very clear and good specification
for information exchange between a routing engine and its client. It reflects
one single node's RIBs associated with multiple Routing Instances supported by
the routing engine.
But the "I2RS Topology", which is also a very good specification describing the
network view of topologies (which consists of multiple nodes and links among them), is
more suited for the entity that manages multiple routing nodes.
RIBs of one routing engine and "topology of multiple routing engines"
definitely represent different perspectives: one is node view, another one is the network
view.
In order to make I2RS widely adopted by the industry, it is very important not
to make it too complicated. Routing is not simple to start with, therefore, it
becomes especially more important to keep I2RS specification simple and to the
point.
Therefore, I suggest to have a paragraph in the "network-topo" draft to
describe that this is for the network view, it is for clients who manage/monitor multiple
routing engines.
My two cents.
Linda
-----Original Message-----
From: Igor Bryskin [mailto:[email protected]]
Sent: Monday, June 29, 2015 1:33 PM
To: Joel M. Halpern; 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
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
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