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Update prefix-and-ip-target.md (aws#2658)
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Corrected a few examples with WARM_PREFIX_TARGET and added another example to the list. Small correction of the text clarifying that a t3.small instance has a maximum of 144 IP addresses in prefix mode, and not 176.
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nicolajknudsen authored and jdn5126 committed Nov 14, 2023
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Expand Up @@ -11,17 +11,18 @@ When a new ENI is allocated, IPAMD will determine the number of prefixes needed
This table demonstrates how prefixes and ENIs will be allocated and use as pods will be created and scheduled to an instance. When reading this table, please keep in mind the following:

* Every instance type has different limits of ENI pre instance type, and secondary IPv4 addresses per ENI. This information is available on our [EC2 Docs](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html#AvailableIpPerENI).
In the example below, `t3.small` was chosen to demonstrate how additional ENIs will be created, since `t3.small` have a maximum of 3 ENIs and 4 IPv4 addresses per ENI. This result in a maximum of 11 available prefixes (3 * 4 minus the primary IPv4 address used by the instance)
In the example below, `t3.small` was chosen to demonstrate how additional ENIs will be created, since `t3.small` have a maximum of 3 ENIs and 4 IPv4 addresses per ENI. This result in a maximum of 9 available prefixes (3 ENIs * (4 IPv4s minus the primary IPv4 address used by the ENI))

* When using prefixes or IPv4 assignment, if the value of `MINIMUM_IP_TARGET` is bigger than N*16, it's equivalent to setting it to (N+1)*16.
The reason for this is because prefixes are allocated as /28 CIDR block or 16 consecutive IP addresses, so asking for minimum of 20 IPv4 addresses is equally as asking 32 IPv4 addresses

| Instance type | `WARM_PREFIX_TARGET` | `WARM_IP_TARGET` | `MINIMUM_IP_TARGET` | Pods | ENIs | Pod per ENIs | Attached Prefixes | Pod per Prefixes | Unused Prefixes | Prefixes per ENI | Unused IPs |
|---------------|:--------------------:|:----------------:|:-------------------:|:----:|:----:|:------------:|:-----------------:|------------------|:---------------:|:----------------:|:----------:|
| t3.small | 1 | - | - | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 16 |
| t3.small | 1 | - | - | 5 | 1 | 5 | 2 | 5 | 1 | 2 | 27 |
| t3.small | 1 | - | - | 17 | 1 | 17 | 3 | 16,1 | 1 | 3 | 31 |
| t3.small | 1 | - | - | 58 | 2 | 48,10 | 5 | 16,16,16,10,0 | 1 | 3,2 | 22 |
| t3.small | 1 | - | - | 5 | 1 | 5 | 2 | 5,0 | 1 | 2 | 27 |
| t3.small | 1 | - | - | 16 | 1 | 16 | 2 | 16,0 | 1 | 2 | 16 |
| t3.small | 1 | - | - | 17 | 1 | 17 | 3 | 16,1,0 | 1 | 3 | 31 |
| t3.small | 1 | - | - | 58 | 2 | 48,10 | 5 | 16,16,16,10,0 | 1 | 3,2 | 22 |
| | | | | | | | | | | | |
| t3.small | - | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 16 |
| t3.small | - | 1 | 1 | 5 | 1 | 5 | 1 | 5 | 0 | 1 | 11 |
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