# Network load balancers access

The **Network Load Balancers access** section is intended for deployment scenarios where third-party front-end load balancers such as Amazon Web Services (AWS) Elastic Load Balancers (ELBs) are used. It allows you to configure an alternate hostname and port number to be used by the Network Load Balancer (NLB). This is needed to separate hostnames and ports on which TCP and HTTPS communications are carried out because AWS load balancers don't support both specific protocols over the same port.

The following options are available:

* **Use alternate hostname:** Select this option and specify an alternate hostname. When the alternate hostname is enabled, all platform-specific Parallels Clients will use this hostname to connect to the RAS Farm or Site.
* **Use alternate port:** Select this option and specify an alternate port number. The port must not be used by any other component in the RAS Farm or Site. To reset the port number to the default value, click **Default**. When the alternate port is enabled, all platform-specific Parallels Clients will use this port to connect to the RAS Farm or Site. Note that RDP sessions in Web Client will still be connecting to the standard SSL port (443).

{% hint style="info" %}
**Note:** Please note that using an alternate host or port is not suitable in a multi-tenant environment as Tenant Broker RAS Secure Gateways are shared between Tenants, which would require different configurations.
{% endhint %}

In addition, the AWS Application Load Balancer (ALB), which handles HTTP/s traffic required by the Parallels Web Client, only supports specific cookies that are usually automatically generated. When a load balancer first receives a request from a client, it routes the request to a target and generates a cookie named `AWSALB`, which encodes information about the selected target. The load balancer then encrypts the cookie and includes it in the response to the client. When sticky sessions are enabled, the load balancer uses the cookie received from the client to route the traffic to the same target, assuming the target is registered successfully and is considered healthy. By default, Parallels RAS uses its own ASP.NET cookie named `_SessionId`, however in this case you must customize the cookie specifying the mentioned AWS cookie for sticky sessions. This can be configured using the **Web cookie** field on the **Web Requests** tab. Please note that this functionality is available in Parallels RAS 17.1 or newer.


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