---
name: vpc-nlb-udp
title: Configuring UDP for network load balancers
description: You can configure the User Datagram Protocol (UDP) for the Network Load Balancer for VPC (NLB) listener and pool. UDP is a communications protocol that establishes low-latency and loss-tolerating connections between applications on the internet. It speeds up transmissions by enabling the transfer of data before an agreement is provided by the receiving party.
last-updated: 2025-06-27
---

> ## Documentation Index
> The table of contents for this documentation set is at https://cloud.ibm.com/docs/vpc?format=markdown
> The index for all IBM Cloud docs is at: https://cloud.ibm.com/docs/llms.txt
> Use these files to discover more information as needed.

# Configuring UDP for network load balancers
{: #nlb-udp}

You can configure the User Datagram Protocol (UDP) for the Network Load Balancer for VPC (NLB) listener and pool. UDP is a communications protocol that establishes low-latency and loss-tolerating connections between applications on the internet. It speeds up transmissions by enabling the transfer of data before an agreement is provided by the receiving party.
{: shortdesc}

The following information does not apply to Private Path network load balancers.
{: note}

UDP is only supported on network load balancers. When configuring UDP and attaching a pool to your listener, you must configure the pool with the same protocol as the listener.
{: important}

For more information about limitations, see [Known issues for network load balancers](https://cloud.ibm.com/docs/vpc?topic=vpc-nlb-limitations&format=markdown) and [Port range limitations](https://cloud.ibm.com/docs/vpc?topic=vpc-nlb-port-ranges&interface=ui&format=markdown#port-range-limitations).

## Configuring UDP using the UI
{: #udp-ui}
{: ui}

You can configure UDP when [creating a network load balancer](https://cloud.ibm.com/docs/vpc?topic=vpc-nlb-ui-creating-network-load-balancer&format=markdown), or afterwards using the following procedure:

1. From your browser, open the [IBM Cloud console](https://cloud.ibm.com/login){: external} and log in to your account.

2. Select the **Navigation menu** ![Menu icon](../icons/icon_hamburger.svg), then click **Infrastructure** ![VPC icon](../../icons/vpc.svg) > **Network** > **Load balancers**.

3. Click the NLB that you want to change.

4. From the NLB details page, select the Front-end listeners tab. Then, select the listener that you want to edit.

   You can also click the **Create listener** button to create a listener.
   {: tip}

   Select the UDP that receives your inbound customer traffic from the Protocol drop-down menu.

5. From the NLB details page, select the Back-end pools tab. Then, select the pool that you want to edit.

   You can also click the **Create pool** button to create a pool.
   {: tip}

   Select the UDP that sends your outbound customer traffic from the Protocol drop-down menu.

## Configuring UDP using the CLI
{: #udp-cli}
{: cli}

You can configure the UDP using the CLI when [creating a network load balancer](https://cloud.ibm.com/docs/vpc?topic=vpc-nlb-ui-creating-network-load-balancer&interface=cli&format=markdown) using the `udp` option.

## Configuring UDP using the API
{: #udp-api}
{: api}

For listeners and pools, you can configure UDP using the API when [creating a network load balancer](https://cloud.ibm.com/docs/vpc?topic=vpc-nlb-ui-creating-network-load-balancer&interface=api&format=markdown) by specifying `udp` for the `protocol` attribute.