VPC native GKE clusters – Container native LB

This blog is last in the series on VPC native GKE clusters. In this blog, I will cover Network endpoint groups(NEG) and Container native load balancing. For the first part on GKE ip addressing, please refer here and the second part on VPC native clusters, please refer here.

Container load balancing and Network endpoint groups(NEG)

Following diagram shows how default Container load balancing works(without NEG). This is applicable to both http and network load balancer.

VPC native GKE clusters – IP aliasing

This blog is second in the series on VPC native GKE clusters. In this blog, I will cover overview of IP aliasing, IP alias creation options and creating VPC native clusters using alias IPs. For the first blog on GKE ip addressing, please refer here.

Overview
IP aliases allows a single VM to have multiple internal IP addresses. These addresses are not the same as having multiple interfaces with each interface having a different IP address. Each of the multiple internal IP address can be used to allocate it for different services running in the VM. When the node is running containers, alias IPs can be used to allocate it to Container pods. GCP VPC network is aware of alias IPs, so the routing is taken care by VPC. Alias IP has significant advantages with GKE Containers since Containers have pod and service IP to manage in addition to the node IP and IP aliasing makes sure that these addresses are native to VPC allowing a tight integration with GCP services.

Alias IP Advantages

VPC native GKE clusters – IP address management

This blog was written by me after a long gap of close to 7 months. Many reasons including busy work schedule, some health issues in the middle and a little bit of laziness contributed to this. I hope to be a more active blogger going forward.

In this blog series, I will cover the following topics:

• GKE default IP address management(without IP aliasing)
• VPC native GKE clusters using IP aliasing
• Container native load balancing using Network Endpoint groups(NEG)

The first blog in this series will talk about GKE default IP address management.

Following are the Kubernetes abstractions that needs IP addresses:

• Node IP address – Assigned to individual nodes. The node ip address is assigned from the VPC subnet range.
• Pod IP address – Assigned to individual pods. All containers within a single pod share same IP address.
• Service IP address- Assigned to individual service

By default, “/14” address gets allocated for cluster IP range. Pod and service IP addresses comes out this pool. “/24” address that comes out of the cluster IP range gets assigned to each individual node and is used for pod IP allocation. “/20” address that comes out of the cluster IP range gets assigned for Kubernetes services. The user has a choice to select cluster IP range when creating the cluster.

To illustrate some of the above points, I have created a 3 node Kubernetes cluster with IP aliasing disabled. By default, VPC native clusters(ip aliasing enabled) is disabled and has to enabled manually. In the future GKE release, VPC native clusters will be the default mechanism.

Cluster output: