GCP 中的 ARP 协议，用于两个虚拟机直接通信

Question

I have two machines within GCP. Both machines are on the same subnet.

The way I understood, GCP is build on SDN and so there is not traditional switching. In other words, there is no ARP recognition for my two machines to communicate directly to each other omiting default gateway.

Am I right? can you please shed some light onto it?

Answer 1

I am not sure what you mean by:

In other words, there is no ARP recognition for my two machines to communicate directly to each other omiting default gateway.

ARP and RARP are supported. ARP lookups are handled in kernel software.

Once two systems have communicated together, the operating systems know about each other and the IP to MAC mapping. If the systems have not communicated previously, then MAC lookup takes place which is managed by the VPC network.

VPC networks use Linux's VIRTIO network module to model Ethernet card and router functionality, but higher levels of the networking stack, such as ARP lookups, are handled using standard networking software.

ARP lookup

The instance kernel issues ARP requests and the VPC network issues ARP replies. The mapping between MAC addresses and IP addresses is handled by the instance kernel.

MAC lookup table, IP lookup table, active connection table

These tables are hosted on the underlying VPC network and cannot be inspected or configured.

Advanced VPC concepts