Allocating additional bandwidth to resources in a datacenter through deployment of dedicated gateways

1. A method of deploying edge forwarding elements in a multi-tenant software defined datacenter (SDDC), the method comprising:

deploying, for a tenant, a first edge forwarding element to process data message flows associated with the tenant;

detecting that the data message flows associated with the tenant consume more than a threshold amount of bandwidth;

based on a policy that specifies allocation of additional bandwidth for data message flows associated with the tenant when the data message flows consume more than the threshold amount, determining that additional bandwidth needs to be allocated for the data message flows associated with the tenant in response to said detecting, wherein the additional bandwidth is for data message flows between a first set of machines in a first network and a second set of machines in a second network external to the first network and the data message flows are data message flows entering or exiting the first network; and

deploying, for the tenant, a second edge forwarding element to process at least a portion of the data message flows associated with the tenant in order to allocate more bandwidth to the tenant, wherein deploying the second edge forwarding element comprises (i) configuring the second edge forwarding element to forward a first subset of the portion of the data message flows to forwarding elements in the external second network and (ii) configuring a set of forwarding elements in the first network to forward the first subset of the data message flows from the first set of machines in the first network to the second edge forwarding element.

2. The method of claim 1 , wherein the first edge forwarding element continues to process a first set of data message flows associated with the tenant, while the second edge forwarding element processes a second set of data message flows associated with the tenant.

3. The method of claim 2 , wherein the first and second sets of data message flows are for two different machines of the tenant that execute in the SDDC.

4. The method of claim 2 , wherein the first and second sets of data message flows are for two different instances of an application that executes in the SDDC for the tenant.

5. The method of claim 2 , wherein the first and second sets of data message flows are for two different components of a multi-component application that executes in the SDDC for the tenant.

6. The method of claim 2 , wherein said deploying, detecting, and determining operations are performed by a set of one or more controllers.

7. The method of claim 1 , wherein configuring the set of forwarding elements in the first network comprises configuring the set of forwarding elements to forward to the second edge forwarding element data message flows with (i) destination IP addresses that are associated with the second edge forwarding element and (ii) source IP addresses associated with the first set of machines for which the additional bandwidth was allocated.

8. The method of claim 7 further comprising configuring a gateway of the SDDC to forward data message flows with destination IP addresses associated with the first set of machines to the second edge forwarding element.

9. The method of claim 1 , wherein:

the edge forwarding elements are edge routers; and

configuring the second edge forwarding element comprises configuring the second edge forwarding element to advertise to forwarding elements in the external, second network routes to the first set of machines.

10. The method of claim 1 , wherein:

the set of forwarding elements comprises a set of intervening routers; and

configuring the set of forwarding elements comprises providing next-hop forwarding rules to the set of intervening routers.

11. The method of claim 1 , wherein:

the set of forwarding elements comprises a set of intervening switches that implement a logical switch; and

configuring the set of forwarding elements comprises providing forwarding rules to the set of intervening switches to direct the switches to forward data messages of the first set to the second edge forwarding element through a set of tunnels that connect the set of intervening switches to the second edge forwarding element.

12. The method of claim 1 , wherein:

the SDDC is a public cloud datacenter having the external second network;

the first network is a private network that is defined in the second network to implement a virtual private cloud (VPC) for the tenant in the public cloud datacenter; and

deploying the second edge forwarding element comprises:

deploying a gateway in the public cloud datacenter to serve as the second edge forwarding element for the VPC; and

configuring a set of forwarding elements in the second network to forward a second subset of the portion of the data message flows from outside of the VPC to the deployed gateway.

13. The method of claim 1 , wherein deploying the first and second edge forwarding elements comprises deploying the first and second edge forwarding elements on different devices in the SDDC.

14. The method of claim 13 , wherein the different devices are first and second host computers on which the first and second edge forwarding elements execute.

15. The method of claim 1 , wherein the SDDC comprises a public cloud datacenter providing compute resources for a plurality of tenants.

16. The method of claim 1 , wherein the SDDC is a private datacenter of an entity and the tenants are different sub-entities associated with the entity.