# Prerequisites for Amazon EC2 topology
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To describe your Amazon EC2 topology, ensure that your instances and Capacity Reservations meet the following prerequisites.

**Topics**
+ [Amazon Web Services Regions](#inst-net-topology-prereqs-regions)
+ [Instance types](#inst-net-topology-prereqs-instance-types)
+ [State](#inst-net-topology-prereqs-instance-state)
+ [IAM permissions](#ec2-instance-topology-iam-permissions)

## Amazon Web Services Regions
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Supported Amazon Web Services Regions:
+ US East (N. Virginia), US East (Ohio), US West (N. California), US West (Oregon)
+ Africa (Cape Town)
+ Asia Pacific (Jakarta), Asia Pacific (Hong Kong), Asia Pacific (Hyderabad), Asia Pacific (Melbourne), Asia Pacific (Mumbai), Asia Pacific (Osaka), Asia Pacific (Seoul), Asia Pacific (Singapore), Asia Pacific (Sydney), Asia Pacific (Tokyo)
+ Canada (Central)
+ Europe (Frankfurt), Europe (Ireland), Europe (London), Europe (Paris), Europe (Spain), Europe (Stockholm), Europe (Zurich)
+ Israel (Tel Aviv)
+ Middle East (Bahrain), Middle East (UAE)
+ South America (São Paulo)
+ Amazon GovCloud (US-West)

The DescribeCapacityReservationTopology API is not supported in Israel (Tel Aviv) and Amazon GovCloud (US-West).

## Instance types
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Supported instance types:
+ Returns **3\$1 network nodes** in the response: 
  + `g6e.xlarge` \$1 `g6e.2xlarge` \$1 `g6e.4xlarge` \$1 `g6e.8xlarge` \$1 `g6e.12xlarge` \$1 `g6e.16xlarge` \$1 `g6e.24xlarge` \$1 `g6e.48xlarge` \$1 `g7e.2xlarge` \$1 `g7e.4xlarge` \$1 `g7e.8xlarge` \$1 `g7e.12xlarge` \$1 `g7e.24xlarge` \$1 `g7e.48xlarge`
  + `hpc6a.48xlarge` \$1 `hpc6id.32xlarge` \$1 `hpc7g.4xlarge` \$1 `hpc7g.8xlarge` \$1 `hpc7g.16xlarge` \$1 `hpc7a.12xlarge` \$1 `hpc7a.24xlarge` \$1 `hpc7a.48xlarge` \$1 `hpc7a.96xlarge` \$1 `hpc8a.96xlarge`
  + `p3dn.24xlarge` \$1 `p4d.24xlarge` \$1 `p4de.24xlarge` \$1 `p5.48xlarge` \$1 `p5e.48xlarge` \$1 `p5en.48xlarge` \$1 `p6e-gb200.36xlarge`
  + `trn1.2xlarge` \$1 `trn1.32xlarge` \$1 `trn1n.32xlarge` \$1 `trn2.48xlarge` \$1 `trn2u.48xlarge`
+ Returns **4\$1 network nodes** in the response: 
  + `p6-b200.48xlarge` \$1 `p6-b300.48xlarge`

\$1 The number of network nodes returned is only applicable when using the DescribeInstanceTopology API. For the DescribeCapacityReservationTopology API, the number of network nodes returned will vary depending on the type and state of the Capacity Reservation.

The available instance types vary by Region. For more information, see [Amazon EC2 instance types by Region](https://docs.amazonaws.cn/ec2/latest/instancetypes/ec2-instance-regions.html).

## State
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+ For `DescribeInstanceTopology` – Instances must be in the `running` state.
+ For `DescribeCapacityReservationTopology` – Capacity Reservations must be in the `pending` or `active` state.

You can’t get topology information for instances or Capacity Reservations in any other state.

## IAM permissions
<a name="ec2-instance-topology-iam-permissions"></a>

Your IAM identity (user, user group, or role) requires the following permissions:
+ `ec2:DescribeInstanceTopology`
+ `ec2:DescribeCapacityReservationTopology`