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Difficulty: EasyConfiguring Network Topology and VPC Infrastructure

A cloud administrator creates a VPC Network Peering connection between VPC-A and VPC-B, and another VPC Network Peering connection between VPC-B and VPC-C. A user attempts to ping a Compute Engine virtual machine in VPC-C directly from a virtual machine in VPC-A, but the traffic is dropped. What is the fundamental VPC networking rule causing this behavior?

  1. VPC Network Peering is non-transitive, so traffic cannot transit through VPC-B to reach VPC-C.Answer
  2. B
    Internal communication across separate VPC networks requires Cloud VPN tunnels instead of network peering.
  3. C
    VPC Service Controls automatically block internal IP traffic between peered networks unless an egress perimeter rule is configured.
  4. D
    Peered VPC networks require control plane authorized network ranges to be registered before Compute Engine instances can exchange traffic.

Answer

VPC Network Peering is non-transitive, so traffic cannot transit through VPC-B to reach VPC-C.
In Google Cloud, VPC Network Peering is non-transitive. Routes established between VPC-A and VPC-B are not passed along to VPC-C through VPC-B's peering connection. As a result, virtual machines in VPC-A cannot communicate directly with virtual machines in VPC-C.

Step-by-Step Solution

1
Examine the peering layout between the three VPC networks.
VPC-A is peered with VPC-B, and VPC-B is peered with VPC-C.
Understand the direct peering connections established.
2
Evaluate Google Cloud VPC Network Peering routing behavior.
Routes learned from a peered network are not re-advertised to other peered networks.
VPC Network Peering is non-transitive by design.
3
Identify why communication between VPC-A and VPC-C fails.
Because VPC-B cannot act as a transit router for peered traffic, VPC-A has no route to reach VPC-C.
Direct communication between VPC-A and VPC-C requires either direct peering between VPC-A and VPC-C or a transit architecture using Cloud VPN or Cloud Router.

Key Concept

VPC Network Peering Transitivity
Estimated Time:1m 0s
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Topics

Configuring Network Topology and VPC Infrastructure

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