NAT vs PAT

Network Address Translation (NAT) and Port Address Translation (PAT) are both methods used to map private IP addresses to public IP addresses, but they operate differently:

 NAT (Network Address Translation)

Function: NAT translates private IP addresses to public IP addresses. This can be done in a one-to-one or many-to-one relationship.

Types: There are two main types of NAT:

Static NAT: Maps a single private IP address to a single public IP address.

Dynamic NAT: Maps a private IP address to a public IP address from a pool of public addresses.

Use Case: NAT is typically used to allow devices within a private network to access the internet by translating their private IP addresses to public ones.

PAT (Port Address Translation)

Function: PAT, also known as NAT overload, extends NAT by mapping multiple private IP addresses to a single public IP address using different port numbers.

Mechanism: PAT uses the transport layer port numbers to distinguish between multiple private IP addresses sharing a single public IP address.

Use Case: PAT is commonly used in home and small office networks to allow multiple devices to share a single public IP address for internet access.

Key Differences

Translation Basis:

• NAT: Translates IP addresses only.
• PAT: Translates both IP addresses and port numbers.

Address Mapping:

• NAT: Can be one-to-one or many-to-one.
• PAT: Always many-to-one, using port numbers to differentiate traffic.

Usage:

• NAT: Suitable for scenarios where a direct mapping of IP addresses is needed.
• PAT: Ideal for conserving public IP addresses by allowing multiple devices to share a single public IP address.