An Edge Gateway can provide load-balancing services that allow you to distribute incoming requests to a specific external IP address across multiple internal IP addresses. Several load-balancing algorithms are supported.

A load balancer service provides load balancing for TCP, HTTP, and HTTPS traffic. The load balancer accepts incoming IP requests on an external or internal interface, and uses the algorithm you specify to distribute requests across a pool of servers.

To add a load-balancer service to an Edge Gateway, include a LoadBalancerService element in the Edge Gateway's EdgeGatewayServiceConfiguration.

This fragment of anEdgeGatewayServiceConfiguration defines a LoadBalancerService that accepts incoming requests at external address https://192.168.1.100 and balances them across two servers at internal addresses 10.200.100.10 and 10.200.100.11. The following elements define a LoadBalancerService:

A Pool that contains ServicePort and Member elements. A LoadBalancerService must include a Pool that defines a ServicePort for each protocol on which the load balancer handles incoming requests. You can define up to three ServicePort elements, one for each supported protocol (HTTP, HTTPS, TCP). This load balancer handles only SSL (HTTPS) requests, so it requires only one ServicePort element in its Pool.

You must specify one of the following load-balancing algorithms in the Algorithm element of the ServicePort.

IP_HASH

Selects a server based on a hash of the source and destination IP address of each packet.

LEAST_CONN

Distributes client requests to multiple servers based on the number of connections already on the server. New connections are sent to the server with the fewest connections.

ROUND_ROBIN

Each server is used in turn according to the weight assigned to it. This is the smoothest and fairest algorithm when the server's processing time remains equally distributed.

URI

The left part of the URI, before the question mark, is hashed and divided by the total weight of the running servers. The result designates which server receives the request, ensuring that a request is always directed to the same server as long as all servers remain available.

The Pool in this example also defines an optional HealthCheck element that specifies parameters used for periodic verification that all pool members are responding to requests.

Each Member element in the Pool specifies the IpAddress of a virtual machine that provides the service being requested. Incoming requests are balanced across all members of the pool. Because the Algorithm specified for this Pool is ROUND_ROBIN, each Member must be assigned a Weight.

A VirtualServer element that defines the Interface, an internal or external interface defined by the containing EdgeGateway, on which requests are accepted.

Note

The network referenced in the Interface element must be configured with an IP sub-allocation.

Note

Each Member of a load balancer Pool can contain its own ServicePort element. If this element is present in a Member, its contents override the ServicePort element of the Pool.

For more information about LoadBalancerService elements and attributes, see the schema reference.

<LoadBalancerService>
   <IsEnabled>true</IsEnabled>
   <Pool>
      <Name>HTTPS_pool</Name>
      <ServicePort>
         <IsEnabled>true</IsEnabled>
         <Protocol>HTTPS</Protocol>
         <Algorithm>ROUND_ROBIN</Algorithm>
         <Port>443</Port>
         <HealthCheck>
            <Mode>TCP</Mode>
            <HealthThreshold>2</HealthThreshold>
            <UnhealthThreshold>3</UnhealthThreshold>
            <Interval>5</Interval>
            <Timeout>15</Timeout>
         </HealthCheck>
      </ServicePort>
      <Member>
         <IpAddress>10.200.100.10</IpAddress>
         <Weight>1</Weight>
      </Member>
      <Member>
         <IpAddress>10.200.100.11</IpAddress>
         <Weight>1</Weight>
      </Member>
   </Pool>
   <VirtualServer>
      <IsEnabled>true</IsEnabled>
      <Name>Example Virtual Server</Name>
      <Description>Incoming LoadBalancerService Requests</Description>
      <Interface
         type="application/vnd.vmware.vcloud.orgVdcNetwork+xml"
         href="https://vcloud.example.com/api/admin/network/199" />
      <IpAddress>192.168.1.100</IpAddress>
      <ServiceProfile>
         <IsEnabled>true</IsEnabled>
         <Protocol>HTTPS</Protocol>
         <Port>443</Port>
         <Persistence>
            <Method>SSL_SESSION_ID</Method>
         </Persistence>
      </ServiceProfile>
      <Logging>true</Logging>
      <Pool>HTTPS_pool</Pool>
   </VirtualServer>
</LoadBalancerService>

To add this service to an Edge Gateway, include it in an EdgeGatewayServiceConfiguration. See Example: Configure Services on an Edge Gateway.