Full form: Port Address Translation
Also known as: Port Address Translation, NAT Overload, NAT overload
Quick Definition
A NAT variant that maps multiple private IP addresses to a single public IP using different port numbers.
PAT (also called NAT Overload) allows many devices to share a single public IP address by using unique source port numbers to distinguish each connection. When an internal host initiates a connection, PAT creates an entry in the translation table mapping the private IP:port to the public IP:unique-port. This is the most common form of NAT used in home routers and small businesses. PAT sessions are tracked in the NAT translation table.
ip nat inside source list 1 interface GigabitEthernet0/0 overload ! PAT using interface IP
PAT uses the 'overload' keyword in the NAT configuration. Without 'overload', you get dynamic NAT (one public IP per private IP from a pool), not PAT.
PAT (also called NAT Overload) allows many devices to share a single public IP address by using unique source port numbers to distinguish each connection. When an internal host initiates a connection, PAT creates an entry in the translation table mapping the private IP:port to the public IP:unique-port. This is the most common form of NAT used in home routers and small businesses. PAT sessions are tracked in the NAT translation table.
PAT uses the 'overload' keyword in the NAT configuration. Without 'overload', you get dynamic NAT (one public IP per private IP from a pool), not PAT.
PAT falls under the IP Services domain of the 200-301 exam. Understanding it in context with related terms like nat and acl is essential for answering scenario-based questions correctly.