---
title: "Attach a reserved IP in TIR"
description: "Attach a reserved public IP to an instance, a virtual machine, or a Slurm cluster, or a VPC IP to an instance or an inference service."
content_type: "how-to"
product: "tir-reserved-ip"
platform: "TIR"
url: "/tir/tir-reserved-ip/how-to/attach-a-reserved-ip/"
topic: ["reserved-ips"]
relationships: {"requires":["/tir/tir-reserved-ip/how-to/reserve-an-ip-address/"]}
---

# Attach a reserved IP in TIR

Attach a reserved IP to give a resource an address that stays the same. A public IP goes to an
instance, a virtual machine, a Slurm cluster, or a Kubernetes cluster. A VPC IP lets an instance or an inference service
reach the VPC privately.

## Before you begin

You need a reserved IP with **Status** **Available**; see
[Reserve an IP](/tir/tir-reserved-ip/how-to/reserve-an-ip-address/). You also need Update
permission on the resource you are attaching it to. If the IP is **Attached**,
[detach it](/tir/tir-reserved-ip/how-to/detach-a-reserved-ip/) first.

For a public IP, the IP and the resource must be in the same project and region. One instance can
hold several reserved IPs. To do this from the instance itself, see
[Manage IP addresses on an instance](/tir/tir-instance/how-to/manage-ip-addresses-on-an-instance/).

For a VPC IP, choose an instance or inference service that has no VPC IP yet, because each holds
one at a time. An inference service also needs at least one security group attached before you
attach a VPC IP; see
[Attach or detach a security group](/tir/tir-security-group/how-to/attach-or-detach-a-security-group/).

## Attach a public IP

1. In TIR, open your project. In the side menu, under **PLATFORM SERVICES**, select **Networking**,
   then **Reserve IP**.
2. In the row of the IP, open the **Action** menu and select **Attach Reserve IP**. This choice is
   available while the IP is **Available**.
3. In **Attach IP**, under **Select Service**, choose **Instance**, **VM**, **Slurm Cluster**, or **Kubernetes Cluster**.
   To choose **Kubernetes Cluster**, you need permission to update Kubernetes clusters.
4. Choose the resource.
5. Select **Attach IP**.

In **Manage Reserved IP**, the IP is now **Attached**, with the resource under **Assigned To**.

You can now reach the resource at the reserved IP. The ports open on that IP are the ports in the
inbound rules of the resource's security groups; see
[Open a port on an instance](/tir/tir-instance/how-to/open-a-port-on-an-instance/).

## Attach a VPC IP

1. In TIR, open your project. In the side menu, under **PLATFORM SERVICES**, select **Networking**,
   then **Reserve IP**.
2. In the row of the VPC IP, open the **Action** menu and select **Attach VPC**. This choice is
   available while the IP is **Available**.
3. In **Attach VPC**, choose **Instance** or **Inference Service**.
4. Choose the resource. You can choose only a resource that has no VPC IP yet.
5. Select **Attach VPC**.

You can also attach from the instance itself. In the instance's actions or its **Network** tab,
choose **Attach VPC**, pick an **Available** VPC IP and select **Attach**, or select
**Reserve New VPC IP**. See
[Manage IP addresses on an instance](/tir/tir-instance/how-to/manage-ip-addresses-on-an-instance/).

The connection moves from **Connecting** to **Connected**. **Idle** means the VPC IP is reserved
and waiting to be attached. If it ends on **Connection Failed**, detach the VPC IP and attach it
again. If it fails a second time, contact support with the resource's ID.

Once connected, the resource reaches the VPC over a private connection. To undo it,
[detach the VPC IP](/tir/tir-reserved-ip/how-to/detach-a-reserved-ip/#detach-a-vpc-ip).

## If the attach fails

[Troubleshooting Reserve IP](/tir/tir-reserved-ip/troubleshooting/tir-reserved-ip/) explains each
message and what to do about it.