Hi George,

I’m working on a blueprint to implement OVS flows for security groups. 
https://blueprints.launchpad.net/neutron/+spec/ovs-firewall-driver Currently, 
neutron only implements security groups with iptables even when Open vSwitch is 
used.

Amir

On Nov 27, 2013, at 1:29 PM, George Shuklin 
<george.shuk...@gmail.com<mailto:george.shuk...@gmail.com>> wrote:


Thank you for reply!

Few more question:

AFAIK bridge tools is not very fast (compare to OVS), so adding them between 
OVS and tap (instead of yet another OVS switch) is kinda slow everything down. 
Why just not use yet another openvswitch switch to connect tap to veth devices?

Why iptables, not internal openvswitch flow rules? Those rules allows to filter 
packets on L2-L4 headers and operates very fast. Is some iptables-only features 
used in ovs-agent?

Thanks.

27.11.2013 20:55 пользователь "Lorin Hochstein" 
<lo...@nimbisservices.com<mailto:lo...@nimbisservices.com>> написал:
Hi George:



On Wed, Nov 27, 2013 at 1:45 PM, George Shuklin 
<george.shuk...@gmail.com<mailto:george.shuk...@gmail.com>> wrote:
Good day.

I looking at the internals of bridge layout of openvswitch agent at 
http://docs.openstack.org/network-admin/admin/content/figures/2/figures/under-the-hood-scenario-1-ovs-compute.png
and wondering, why this scheme is so complicated and why it use linux bridge 
and vethes with openvswitch together? Why no just plug tap device directly to 
openvswitch bridge without intermediate brctl bridge?

I guess that was caused by some important consideration, but I unable to find 
any documents about this.

If someone know reasons for that complex construction with different bridges, 
please response.


If you look a little further down on the page with that figure, the 
documentation reads

Ideally, the TAP device vnet0 would be connected directly to the integration 
bridge, br-int. Unfortunately, this isn't possible because of how OpenStack 
security groups are currently implemented. OpenStack uses iptables rules on the 
TAP devices such as vnet0 to implement security groups, and Open vSwitch is not 
compatible with iptables rules that are applied directly on TAP devices that 
are connected to an Open vSwitch port.


Take care,

Lorin



--
Lorin Hochstein
Lead Architect - Cloud Services
Nimbis Services, Inc.
www.nimbisservices.com<http://www.nimbisservices.com/>

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