AWS – Using a Network Load Balancer

AWS Load Balancer Specific Settings

Deploying a Network Load Balancer

The Network Load Balancer (NLB) forwards incoming traffic to instances registered in the target group. NLB can be made redundant across multiple Availability Zones (AZs). In this case, NLB IP addresses are assigned to each subnet and cannot be used for client access. Therefore, you need to use the DNS name of the NLB for client access. Since the DNS name of the NLB is converted to one of the IP addresses, you can access the client using the same DNS name even when an AZ fails. By default, traffic forwarded to an NLB IP address can only be forwarded to targets on that subnet. By enabling cross-zone load balancing, it can be forwarded to targets in different subnets.

Connecting from the client

1. The Client attempts to connect to the application (Listener in the above figure) with the NLB DNS name and the port number of the application (XXXX-nlb1-YYYYY.elb.region.amazonaws.com and 1521 in the above figure). The DNS name is converted to the IP address of the NLB subnet via AWS internal Route 53 (10.0.1.151 or 10.0.2.181 in the above example).
2. The NLB registers the target group to which it should forward specific protocols and ports. At this time, check on which node responds to the health probe.
3. The active node responds to health probes. With LifeKeeper, LB Health Check resource is active on only one instance, so only the active node responds to the NLB health probe, meaning that the NLB will always forward traffic only to the active node (in the figure above, AWSNODE1 is active).
4. The NLB forwards connection requests from clients to the active node. The connection request then reaches the active node with the destination address replaced from the NLB address to the active node’s real IP address (10.0.1.10 in the figure above).

Creating a Network Load Balancer

Create a network load balancer according to the following table.

Enabling cross-zone load balancing

Cross-zone load balancing is disabled by default, so enable it from “Edit load balancer attributes”.

Tuning parameters configured in health check details

See Tuning Load Balancer Health Check Parameters.

Creating IP Resources

When using a resource that requires an IP resource, such as an Oracle resource, create an IP resource as a real IP address. Traffic is forwarded from the NLB to the real IP address.

Creating an LB Health Check Resource

See Responding to Load Balancer Health Checks.