[openstack-dev] [Neutron] support of NSH in networking-SFC

Elzur, Uri uri.elzur at intel.com
Wed May 25 04:53:21 UTC 2016

Hi Tim

Sorry for the delay due to travel...

This note is very helpful! 

We are in agreement that the team including the individuals cited below are supportive. We also agree that SFC belongs in the networking-SFC project (with proper API adjustment)

It seems networking-sfc still holds the position that without OvS accepting VXLAN-gpe and NSH patches they can't support NSH. I'm trying to get a clear read on where is this stated as requirement

Like you, we are closely following the progress of the patches and honestly I have hard time seeing OpenStack supporting NSH in production even by the end of 2017. I think this amounts to slowing down the market...

I think we need to break the logjam. 

I've reviewed (https://review.openstack.org/#/c/312199/12/specs/newton/neutron-stadium.rst,unified) and found nowhere a guideline suggesting that before a backend has fully implemented and merged upstream a technology (i.e. another project outside of OepnStack!), OpenStack Neutron can't make any move. ODL is working >2 years to support NSH using patches, yet to be accepted into Linux Kernel (almost done) and OvS (preliminary) - as you stated. Otherwise we create a serialization, that gets worse and worse over time and with additional layers. 

No one suggests the such code needs to be PRODUCTION, but we need a way to roll out EXPERIMENTAL functions and later merge them quickly when all layers are ready, this creates a nice parallelism and keeps a decent pace of rolling out new features broadly supported elsewhere.


Uri (“Oo-Ree”)
C: 949-378-7568

-----Original Message-----
From: Tim Rozet [mailto:trozet at redhat.com] 
Sent: Friday, May 20, 2016 7:01 PM
To: OpenStack Development Mailing List (not for usage questions) <openstack-dev at lists.openstack.org>; Elzur, Uri <uri.elzur at intel.com>
Cc: Cathy Zhang <Cathy.H.Zhang at huawei.com>
Subject: Re: [openstack-dev] [Neutron] support of NSH in networking-SFC

Hi Uri,
I originally wrote the Tacker->ODL SFC NSH piece and have been working with Tacker and networking-sfc team to bring it upstream into OpenStack.  Cathy, Stephen, Louis and the rest of the networking-sfc team have been very receptive to changes specific to NSH around their current API and DB model.  The proper place for SFC to live in OpenStack is networking-sfc, while Tacker can do its orchestration job by rendering ETSI MANO TOSCA input like VNF Descriptors and VNF Forwarding Graph Descriptors.

We currently have a spec in netwoking-odl to migrate my original driver for ODL to do IETF NSH.  That driver will be supported in networking-sfc, along with some changes to networking-sfc to account for NSH awareness and encap type (like VXLAN+GPE or Ethernet).  The OVS work to support NSH is coming along and patches are under review.  Yi Yang has built a private OVS version with these changes and we can use that for now to test with.

I think it is all coming together and will take a couple more months before all of the pieces (Tacker, networking-sfc, networking-odl, ovs) are in place.  I don't think networking-sfc is holding up any progress.


Tim Rozet
Red Hat SDN Team

----- Original Message -----
From: "Uri Elzur" <uri.elzur at intel.com>
To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org>, "Cathy Zhang" <Cathy.H.Zhang at huawei.com>
Sent: Friday, May 20, 2016 8:37:26 PM
Subject: Re: [openstack-dev] [Neutron] support of NSH in networking-SFC

Hi Armando, Cathy, All 

First I apologize for the delay, returning from a week long international trip. (yes, I know, a lousy excuse on many accounts…) 

If I’m attempting to summarize all the responses, it seems like 

· A given abstraction in Neutron is allowed (e.g. in support of SFC), preferably not specific to a given technology e.g. NSH for SFC 

· A stadium project is not held to the same tests (but we do not have a “formal” model here, today) and therefore can support even a specific technology e.g. NSH (definitely better with abstractions to meet Neutron standards for future integration) 


· There still is a chicken and egg phenomenon… how can a technology become main stream with OPEN SOURCE support if we can’t get an OpenStack to support the required abstractions before the technology was adopted elsewhere?? 

o Especially as Stadium, can we let Neutron to lead the industry, given broad enough community interest? 

· BTW, in this particular case, there originally has been a direct ODL access as a NSH solution (i.e. NO OpenStack option), then we got Tacker (now an Neutron Stadium project, if I get it right) to support SFC and NSH, but we are still told that networking-sfc (another Neutron Stadium project ) can’t do the same…. 

· Also regarding the following comment made on another message in this thread, “ As to OvS features, I guess the OvS ml is a better place, but wonder if the Neutron community wants to hold itself hostage to the pace of other projects who are reluctant to adopt a feature ”, what I mean is again, that chicken and egg situation as above. Personally, I think OpenStack Neutron should allow mechanisms that are of interest / value to the networking community at large, to “ experiment with the abstraction” as you stated, independent of other organizations/projects … 

SOOO, is the bottom line that we agree that supporting NSH explicitly in networking-sfc can be added now? 


Uri (“Oo-Ree”) 

C: 949-378-7568 

From: Armando M. [mailto:armamig at gmail.com] 
Sent: Friday, May 13, 2016 5:14 PM 
To: Cathy Zhang <Cathy.H.Zhang at huawei.com> 
Cc: OpenStack Development Mailing List (not for usage questions) <openstack-dev at lists.openstack.org> 
Subject: Re: [openstack-dev] [Neutron] support of NSH in networking-SFC 

On 13 May 2016 at 16:01, Cathy Zhang < Cathy.H.Zhang at huawei.com > wrote: 

Hi Uri, 

Current networking-sfc API allows the user to specify the data path SFC encapsulation mechanism and NSH could be one of the encapsulation options. 

But since OVS release has not supported the NSH yet, we have to wait until NSH is added into OVS and then start to support the NSH encapsulation mechanism in the data path. 

One can support NSH whichever way they see fit. NSH in OVS is not something Neutron can do anything about. Neutron is about defining abstractions that can apply to a variety of technologies and experiment with what open source component is available on the shelves. Anyone can take the abstraction and deliver whatever technology stack they want with it and we'd happily gather any feedback to iterate on the abstraction to address more and more use case. 

AFAIK, it is the position of Neutron to have any OVS related new features developed inside the OVS community. 



From: Elzur, Uri [mailto: uri.elzur at intel.com ] 
Sent: Friday, May 13, 2016 3:02 PM 
To: OpenStack Development Mailing List (not for usage questions); Armando M 
Subject: [openstack-dev] [Neutron] support of NSH in networking-SFC 

Hi Armando 

As an industry we are working on SFC for 3 years or so (more?). Still to date, we are told we can’t get Neutron or even a Stadium project e.g. networking-SFC to support NSH (in IETF LC phase) because OvS has not supported NSH. Is this an official position of Neutron that OvS is the gold standard to support any new feature? 

We have seen OvS support other overlays that are not ahead of VXLAN-gpe in the IETF. 


Uri (“Oo-Ree”) 

C: 949-378-7568 

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