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

Cathy Zhang Cathy.H.Zhang at huawei.com
Wed Jun 1 18:54:12 UTC 2016

Looks like the work of removing the mandatory L3 requirement associated with decapsulated VxLAN-gpe packet also involves OVS kernel change, which is difficult. Furthermore, even this blocking issue is resolved and eventually OVS accepts the VLAN-gpe+NSH encapsulation, there is still another issue. 
Current Neutron only supports VXLAN, not VXLAN-gpe, and adopting VXLAN-gpe involves consideration of backward compatibility with existing VXLAN VTEP and VXLAN Gateway. 

An alternative and maybe easier/faster path could be to push a patch of " VxLAN + Eth + NSH + Original frame" into OVS kernel. This is also IETF compliant encapsulation for SFC and does not have the L3 requirement issue and Neutron VXLAN-gpe support issue. 

We can probably take this discussion to the OVS mailing alias. 


-----Original Message-----
From: Ben Pfaff [mailto:blp at ovn.org] 
Sent: Tuesday, May 31, 2016 9:48 PM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [Neutron] support of NSH in networking-SFC

On Wed, Jun 01, 2016 at 12:08:23AM +0000, Yang, Yi Y wrote:
> Ben, yes, we submitted nsh support patch set last year, but ovs 
> community told me we have to push kernel part into Linux kernel tree, 
> we're struggling to do this, but something blocked us from doing this.

It's quite difficult to get patches for a new protocol into the kernel.
You have my sympathy.

> Recently, ovs did some changes in tunnel protocols which requires the 
> packet decapsulated by a tunnel must be a Ethernet packet, but Linux 
> kernel (net-next) tree accepted VxLAN-gpe patch set from Redhat guy 
> (Jiri Benc) which requires the packet decapsulated by VxLAN-gpe port 
> must be L3 packet but not L2 Ethernet packet, this blocked us from 
> progressing better.
> Simon Horman (Netronome guy) has posted a series of patches to remove 
> the mandatory requirement from ovs in order that the packet from a 
> tunnel can be any packet, but so far we didn't see they are merged.

These are slowly working their way through OVS review, but these also have a prerequisite on kernel patches, so it's not easy to get them in either.

> I heard ovs community looks forward to getting nsh patches merged, it 
> will be great if ovs guys can help progress this.

I do plan to do my part in review (but much of this is kernel review, which I'm not really involved in anymore).

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