Processing data messages of a virtual network that are sent to and received from external service machines
Some embodiments establish for an entity a virtual network over several public clouds of several public cloud providers and/or in several regions. In some embodiments, the virtual network is an overlay network that spans across several public clouds to interconnect one or more private networks (e.g., networks within branches, divisions, departments of the entity or their associated datacenters), mobile users, and SaaS (Software as a Service) provider machines, and other web applications of the entity. The virtual network in some embodiments can be configured to optimize the routing of the entity's data messages to their destinations for best end-to-end performance, reliability and security, while trying to minimize the routing of this traffic through the Internet. Also, the virtual network in some embodiments can be configured to optimize the layer 4 processing of the data message flows passing through the network.
1. For a multi-tenant virtual network system, a method of processing data messages that are associated with virtual networks that are defined for different tenants over a set of public cloud datacenters, the method comprising:
at an ingress gateway through which the data messages enter the virtual networks;
receiving a data message associated with a particular tenant with a particular virtual network;
determining that the received data message is associated with an external service machine outside of the particular virtual network and the plurality of public cloud datacenters;
based on a tenant identifier (TID) that identifies the particular tenant in the multi-tenant virtual network control system and that the multi-tenant virtual network system associates with the particular tenant, performing a first source network address translation (SNAT) operation to modify an original source network address of the received data message to a first source network address; and
performing a second SNAT operation to modify the first source network address associated with the data message to a modified second source network address,
the first SNAT operations mapping the data messages of different tenants to different source network address spaces to ensure that even when a common network address space is used for two tenants, the modified second source network addresses of the different tenants do not overlap; and
at an egress gateway from which the data messages exit the virtual networks;
performing a third SNAT operation to modify the modified second source network address of the received data message to a modified third source network address; and
forwarding the received data message, with the modified third source network address to the external service machine through an external network that is outside of the public cloud datacenters.
2. The method of claim 1 , wherein both the second and third SNAT operations are stateful processes each of which creates a record associated with a flow identifier of the received data message to use to process subsequent data messages that are part of the received data message's flow.
3. The method of claim 1 , wherein
the first source network address is a network address in a private network address space of an entity that is not one of the public cloud providers; and
the second and third source network addresses are network addresses in a public network address space.
4. The method of claim 1 , wherein:
the first source network address is a network address in a private network address space of an entity that is not one of the public cloud providers;
the second source network address is a network address in a private network address space of a public cloud provider; and
the third source network address is a network address in a public network address space.
5. The method of claim 1 , wherein the ingress and egress gateways are forwarding elements that are deployed and configured in the set of public cloud datacenters to implement the virtual networks over the public cloud datacenters.
6. The method of claim 1 , wherein the first, second, and third network addresses each comprises a layer 3 network address.
7. The method of claim 1 , wherein:
the first, second and third network addresses each comprises a layer 3 network address and a layer 4 network addres; and
at least one of the first, second, and third SNAT operations modifies both the layers 3 and 4 network addresses.
8. The method of claim 7 , wherein each of the first, second, and third SNAT operations modifies both the layers 3 and 4 network addresses.
9. The method of claim 1 , wherein determining that the received data message is associated with an external service machine comprises:
extracting a destination network address from a header of the received data message; and
using the extracted destination network address to determine that the received data message's destination address is associated with an interface connected to a machine outside of the public cloud datacenters.
10. The method of claim 9 , wherein
the external network is the Internet; and
using the extracted destination network address comprises performing a lookup operation in the public Internet context based on the extracted destination network address.
11. The method of claim 1 , wherein the external service machine is a machine of a SaaS (software as a service) provider, while a source of the data message is one of a machine in an office of the particular tenant, a machine in a private datacenter of the particular tenant, or a remote user machine of the particular tenant.
12. The method of claim 11 , wherein the service machine is in a private datacenter of the SaaS provider.
13. The method of claim 1 further comprising creating at least one record for the first and second SNAT operations in order to use the record to perform at least one destination network address translation operation for a data message received from the external service machine.
14. The method of claim 1 , wherein the set of public cloud datacenters comprises a plurality of multi-tenant public cloud datacenters.