Tricircle project has decided to shrink its scope to networking automation 
across Neutron, and focus on addressing the networking requirements in 
following use cases:

1. Cloud Capacity Expansion

When one OpenStack cloud is provisioned with more and more resources, the 
capacity of one OpenStack instance may not be enough. A new openstack instance 
has to be added to the cloud. But tenants still want to add VMs to existing 

2. Application high availability running over cloud

In telecom and other industries(for example, MySQL Galera cluster), normally 
applications tend to be designed as Active-Active, Active-Passive or N-to-1 
node configurations. Because those applications need to be available as much as 
possible. Once those applications are planned to be migrated to cloud 
infrastructure, active instance(s) need(s) to be deployed in one OpenStack 
instance first. After that, passive or active instances(s) will be deployed in 
another (other) OpenStack instance(s) in order for achieving 99.999% 
availability, if it’s required. The reason why this deployment style is 
required is that in general cloud system only achieve 99.99% availability.

To achieve required high availability, design of network architecture 
(especially Layer 2 and Layer 3) across Neutron needs to be considered for 
application state replication or heartbeat.

3. Isolation of East-West traffic

In financial industry, more than one OpenStack instances will be deployed, some 
OpenStack instance will be put in DMZ zone, and the other ones in trust zone, 
so that application or part of the application could be put in different level 
security zone. Although the tenant’s resources are provisioned in different 
OpenStack instances, east-west traffic among the tenant’s resources should be 

Bandwidth sensitive, heavy load App like CAD modeling asked for the cloud close 
to the end user in distributed edge site for better user experience, multiple 
OpenStack instances will be deployed into edge sites, but the east-west 
communication with isolation between the tenant’s resources are also required.

4. Dual ISPs Load Balancing for internet link

Deploy application in separate OpenStack instance with dual ISPs for internet 
link redundancy, load balancing, east-west traffic isolation for data/state 
replication is needed.

5. Cross Neutron L2 network for NFV area

IN NFV(Network Function Virtualization) area, network functions like router, 
NAT, LB etc will be virtualized, The cross Neutron L2 networking capability 
like IP address space management, IP allocation and L2 network segment global 
management provided by the Tricircle can help VNFs(virtualized network 
function) across site inter-connection. For example, vRouter1 in site1, but 
vRouter2 in site2, these two VNFs could be in one L2 network across site.

The common requirements for above use cases are:

1. Tenant's resources will be located in different OpenStack instances, 
networking across Neutron required.

2. IP/Mac address management across Neutron to avoid conflict.

3. East-west L2/L3 traffic for the tenant should be isolated. No matter using 
VPN or not.

4. If L2 network will be stretched into multiple Neutron, global network 
segment management is required.

5. Security group should work for VMs in different OpenStack instances.

... etc.

Although Tricircle splitting and cleaning is WIP, some draft materials were 
prepared for open comments and to be improved with your contribution:

1. Tricircle focuses on networking automation across Neutron:

2. Tricircle design blueprint update:

3. Tricircle wiki update:

(Caution: the git repo. of Tricircle will be purified, nova_apigw and 
cinder_apigw will be removed from the repo. soon , the description will also be updated)

There are also some requirements to Neutron to support cross Neutron networking 
automation, for example, to support VxLAN network across Neutron (6.5.3 Shared 
VxLAN, point2point,,
 IP/mac list needs to be added for different VTEP in the patch  for better data plane performance.

If you are interested in the L2/L3 networking automation across Neutron, it 
will be good to have a BoF to meet and discuss f2f in Barcelona.

Best Regards
Chaoyi Huang (joehuang)
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