kubernetes-the-hard-way/docs/11-pod-network-routes.md

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# Provisioning Pod Network Routes
Pods scheduled to a node receive an IP address from the node's Pod CIDR range. At this point pods can not communicate with other pods running on different nodes due to missing network [routes](https://cloud.google.com/compute/docs/vpc/routes).
In this lab you will create a route for each worker node that maps the node's Pod CIDR range to the node's internal IP address.
> There are [other ways](https://kubernetes.io/docs/concepts/cluster-administration/networking/#how-to-achieve-this) to implement the Kubernetes networking model.
## The Routing Table
In this section you will gather the information required to create routes in the `kubernetes-the-hard-way` VPC network.
Print the internal IP address and Pod CIDR range for each worker instance:
#### Linux & OS X
```
for instance in worker-0 worker-1 worker-2; do
gcloud compute instances describe ${instance} \
--format '(networkInterfaces[0].networkIP,metadata.items[0].value)'
done
```
#### Windows
```
@('worker-0','worker-1','worker-2') | ForEach-Object {
gcloud compute instances describe $_ `
--format "value[separator=' '](networkInterfaces[0].networkIP,metadata.items[0].value)"
}
```
> output
```
10.240.0.20 10.200.0.0/24
10.240.0.21 10.200.1.0/24
10.240.0.22 10.200.2.0/24
```
## Routes
Create network routes for each worker instance:
#### Linux & OS X
```
for i in 0 1 2; do
gcloud compute routes create kubernetes-route-10-200-${i}-0-24 \
--network kubernetes-the-hard-way \
--next-hop-address 10.240.0.2${i} \
--destination-range 10.200.${i}.0/24
done
```
#### Windows
```
@(0, 1, 2) | ForEach-Object {
gcloud compute routes create kubernetes-route-10-200-${_}-0-24 `
--network kubernetes-the-hard-way `
--next-hop-address 10.240.0.2${_} `
--destination-range 10.200.${_}.0/24
}
```
List the routes in the `kubernetes-the-hard-way` VPC network:
```
gcloud compute routes list --filter "network: kubernetes-the-hard-way"
```
> output
```
NAME NETWORK DEST_RANGE NEXT_HOP PRIORITY
default-route-77bcc6bee33b5535 kubernetes-the-hard-way 10.240.0.0/24 1000
default-route-b11fc914b626974d kubernetes-the-hard-way 0.0.0.0/0 default-internet-gateway 1000
kubernetes-route-10-200-0-0-24 kubernetes-the-hard-way 10.200.0.0/24 10.240.0.20 1000
kubernetes-route-10-200-1-0-24 kubernetes-the-hard-way 10.200.1.0/24 10.240.0.21 1000
kubernetes-route-10-200-2-0-24 kubernetes-the-hard-way 10.200.2.0/24 10.240.0.22 1000
```
Next: [Deploying the DNS Cluster Add-on](12-dns-addon.md)