[openstack-dev] [neutron] Neutron scaling datapoints?

joehuang joehuang at huawei.com
Sat Apr 11 01:00:39 UTC 2015

Hi, Neil, 

See inline comments.

Best Regards

Chaoyi Huang

From: Neil Jerram [Neil.Jerram at metaswitch.com]
Sent: 09 April 2015 23:01
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [neutron] Neutron scaling datapoints?

Hi Joe,

Many thanks for your reply!

On 09/04/15 03:34, joehuang wrote:
> Hi, Neil,
>  From theoretic, Neutron is like a "broadcast" domain, for example, enforcement of DVR and security group has to touch each regarding host where there is VM of this project resides. Even using SDN controller, the "touch" to regarding host is inevitable. If there are plenty of physical hosts, for example, 10k, inside one Neutron, it's very hard to overcome the "broadcast storm" issue under concurrent operation, that's the bottleneck for scalability of Neutron.

I think I understand that in general terms - but can you be more
specific about the broadcast storm?  Is there one particular message
exchange that involves broadcasting?  Is it only from the server to
agents, or are there 'broadcasts' in other directions as well?

[[joehuang]] for example, L2 population, Security group rule update, DVR route update. Both direction in different scenario.

(I presume you are talking about control plane messages here, i.e.
between Neutron components.  Is that right?  Obviously there can also be
broadcast storm problems in the data plane - but I don't think that's
what you are talking about here.)

[[joehuang]] Yes, controll plane here.

> We need layered architecture in Neutron to solve the "broadcast domain" bottleneck of scalability. The test report from OpenStack cascading shows that through layered architecture "Neutron cascading", Neutron can supports up to million level ports and 100k level physical hosts. You can find the report here: http://www.slideshare.net/JoeHuang7/test-report-for-open-stack-cascading-solution-to-support-1-million-v-ms-in-100-data-centers

Many thanks, I will take a look at this.

> "Neutron cascading" also brings extra benefit: One cascading Neutron can have many cascaded Neutrons, and different cascaded Neutron can leverage different SDN controller, maybe one is ODL, the other one is OpenContrail.
> ----------------Cascading Neutron-------------------
>              /         \
> --cascaded Neutron--   --cascaded Neutron-----
>         |                  |
> ---------ODL------       ----OpenContrail--------
> And furthermore, if using Neutron cascading in multiple data centers, the DCI controller (Data center inter-connection controller) can also be used under cascading Neutron, to provide NaaS ( network as a service ) across data centers.
> ---------------------------Cascading Neutron--------------------------
>              /            |          \
> --cascaded Neutron--  -DCI controller-  --cascaded Neutron-----
>         |                 |            |
> ---------ODL------           |         ----OpenContrail--------
>                           |
> --(Data center 1)--   --(DCI networking)--  --(Data center 2)--
> Is it possible for us to discuss this in OpenStack Vancouver summit?

Most certainly, yes.  I will be there from mid Monday afternoon through
to end Friday.  But it will be my first summit, so I have no idea yet as
to how I might run into you - please can you suggest!

I will also attend the summit whole week, sometimes in the OPNFV parts, sometimes in OpenStack parts. Let me see how to meet.

> Best Regards
> Chaoyi Huang ( Joe Huang )


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