66 Red Hat OpenShift and IBM Cloud Paks on IBM Power Systems: Volume 1
Finally, if the Pod connects to an external host, the traffic flow from the eth0 interface in the 
pod to the vethX in the Linux bridge then to the br0 interface in the OVS uses the tun0 
interface through the eth0 to the physical network.
Almost all packet delivery decisions are performed with OpenFlow rules in the OVS bridge 
br0, which simplifies the plug-in network architecture and provides flexible routing. In the case 
of the ovs-multitenant plug-in, this configuration also provides enforceable network isolation.
4.2.3  OpenShift external cluster communication
OpenShift Container Platform provides different ways to access the applications or services 
that are running inside the cluster. 
Administrators can make available a service endpoint that external traffic can reach by 
assigning a unique external IP address to that service from a range of external IP addresses. 
This IP address range is specified by using a CIDR notation, which allows an application user 
to make a request against the cluster for an external IP address.
Each IP address must be assigned to only one service to ensure that each service has a 
unique endpoint. 
The recommendation, in order or preference, is:
/SM590000Use a router if you use HTTP/HTTPS or TLS-encrypted protocol other than HTTPS. 
/SM590000Use a Load Balancer, an External IP, or a NodePort.
OpenShift Container Platform Router plug-in
The following OpenShift Router plug-ins are available:
/SM590000HAProxy Template Router: The HAProxy template uses the openshift3/ose-haproxy-router 
image to deploy one or more Router Pods (container) that are running on Infrastructure 
Nodes on the OpenShift Container Platform.
/SM590000F5 BIG-IP Router plug-in: The F5 router integrates with a F5 BIG-IP system in your 
environment to synchronize routes. F5 BIG-IP version 11.4 or newer is required to have 
the F5 iControl REST API.
For more information about the use of the router HAProxy plug-in, see this web page.
Assigning a public IP by using a load balancer service
This method allows traffic to nonstandard ports through an IP address that is assigned from a 
pool.
If you do not need a specific external IP address, you can configure a load balancer service to 
allow external access to an OpenShift Container Platform cluster.
A load balancer service allocates a unique IP from a configured pool. The load balancer 
features a single edge router IP (which can be a virtual IP (VIP), but is still a single machine 
for initial load balancing).
Manually assigning an external IP to a service
A Kubernetes service serves as an internal load balancer. It identifies a set of replicated pods 
to proxy the connections it receives to them. Backing pods can be added to or removed from 
a service arbitrarily, although the service remains consistently available, which enables 
anything that depends on the service to refer to it at a consistent address.