11.10 NAT Overview

CCNP RS 300-101, Establishing Internet Connectivity, Uncategorized

NAT Types:

  • Static NAT = a 1:1 mapping, often used for hosting services to external clients
  • Dynamic NAT = A many-to-many mapping, often used to circumvent issues with company mergers (and other use cases)
  • PAT = A many-to-one mapping, often used to facilitate outbound enterprise internet access

Types of NAT Addresses:

  • Inside local address = The real address, assigned directly to a node on the internal network
  • Inside global address = The mapped/translated IP of the Real address, as it appears to an external network
  • Outside local address = The mapped/translated IP of an external node, as it appears to a node on the internal network
  • Outside global address = The real address of an external node

Issue the show ip nat translations command to view these different addresses:

The inside and outside designations apply regardless of traffic direction; if a connection is initiated by an external network, the remote IP appearing to the internal node (for return traffic) is still an outside local address.

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