GCP Classroom Series – 19/Feb/2021

Understanding Routing in GCP VPC

• Lets understand how to create and manage routes in GCP VPC.

• Lab Exercise

  • Create a custom network with two subnets in us-central1 and us-east1
  • Create one more custom network with two subnets in us-central and us-east
  • Ensure they dont have colliding ip ranges
  • Now create a firewall rule which allows anyone to access ssh (22 port) and also create a firewall rule to icmp in both the networks
  • Now create a linux vm in vpca in subnet in region us-central1 with external and internal ip address
  • Now create a linux vm in vpcb in subnet in region us-central1 with external and internal ip address
  • Now login into vm in vpc a and try to ping
    • yahoo.com
    • vm in vpc b using external ip
    • vm in vpc b using internal ip
  • Now create one more vm in vpc a in us-east1 with no external ip
  • Now from vm in vpca try to ping to vm 2 in vpc-a
  • Now try to login using ssh from vm in vpca into vm2 in vpc-a
    • you will not be able to ssh as keys are not shared
    • Try connecting to ssh using browser session
  • Check the interet access
  • Try to access the vm in vpc-a from vm 2 in vpc-a using internal and external ip address

• When we create a vpc in google cloud System Generated Routes are Created, There are two kinds of System Generated Routes

  • Default Route:
    • Default rout out of your vpc to external Internet
    • Provides path for Private Google Access
    • This can be deleted
  • Subnet Route
    • Defines a destination path for each vpc subnet
    • Cannot be deleted

• Every Route will have single destination + single next hop

• Note: Purpose of NAT Server

• Create a Cloud NAT

• Next Steps: Configure the cloud NAT to resolve the external communication to private instance