Copyright 2003 NAT A NAT-enabled device typically operates at the border of a stub network.
Copyright 2003 NAT Terms Inside local address The IP address assigned to a host on the inside network. This address is likely to be an RFC 1918 private address. Inside global address A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP addresses to the outside world. Outside local address The IP address of an outside host as it known to the hosts in the inside network. Outside global address The IP address assigned to a host on the outside network. The owner of the host assigns this address.
Copyright 2003 NAT Features Static NAT is designed to allow one-to-one mapping of local and global addresses. Dynamic NAT is designed to map a private IP address to a public address.
Copyright 2003 PAT Features PAT uses unique source port numbers on the inside global IP address to distinguish between translations.
Copyright 2003 NAT Benefits Eliminates re-assigning each host a new IP address when changing to a new ISP Eliminates the need to re-address all hosts that require external access, saving time and money Conserves addresses through application port-level multiplexing Protects network security
Copyright 2003 DHCP DHCP works by providing a process for a server to allocate the IP information to clients. Clients lease the information from the server for an administratively defined period.
Copyright 2003 BOOTP and DHCP Differences DHCP defines mechanisms through which clients can be assigned an IP address for a finite lease period. This lease period allows for re-assignment of the IP address to another client later, or for the client to get another assignment, if the client moves to another subnet. Clients may also renew leases and keep the same IP address. DHCP provides the mechanism for a client to gather other IP configuration parameters, such as WINS and domain name.